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33
RREESSUULLTTSS AANNDD DDIISSCCUUSSSSIIOONN
In the present work, removal of Methylene Blue (MB), Methyl Violet (MV), Acid Blue
(AB) and Acid Violet (AV) dyes are carried out using a bio waste, Blue-Green Algae (BGA)
as an adsorbent by adsorption technique. The adsorption studies are performed by
conducting batch mode experiments by varying the parameters such as initial concentration
of the dye solution, pH, adsorbent dosage, agitation time and temperature. The
experimental data obtained and the findings of the present study are interpreted and
discussed in the light of the objectives set forth. The results are used to evaluate the
optimum conditions for the removal of these dyes from aqueous solution and to examine
the efficiency of the low cost adsorbent BGA for the treatment of dyeing industrial effluent
containing these dyes by adsorption.
4.1 Characteristics of the Adsorbent BGA
The characteristics namely Moisture Content, pH, Surface Area and Pore Diameter of
the adsorbent Blue-Green Algae (BGA) used in this study are given in Table 2.
Table 2
Characteristics of the Adsorbent BGA
S.No. Physical Characters ForAdsorbent BGA
1. Moisture Content (%) 5.4
2. pH 5.7
3. Surface Area (m2/g) [Appendix II] 479
4. Pore Diameter (µm) [obtained from SEMAnalysis] 10.39 -10.98
The Surface Area of the adsorbent, Commercial Activated Carbon (CAC) used in this
study is 1021m2/g (Appendix III).
4
34
4.2 Effect of Initial Concentration of Dye Solution on Dye Removal
The study of the distribution of the dye between the adsorbent and the dye solution at
equilibrium is important to assess the adsorption capacity of the adsorbent for the
dyestuffs. The initial concentration of the dye solutions are varied from 60 to 120mg/l and
batch mode experiments are performed at 32 ± 2ºC and at pH 7.0 ± 0.2 to study the effect
of initial concentration of dye solutions on the removal of dye from aqueous solution and
from dyeing industrial effluent with 500mg of the adsorbent BGA by varying the agitation
time from 10 to 180 minutes.
The study reveals that the percentage removal of all the dyes (MB, MV, AB and AV)
from aqueous solution and from dyeing industrial effluent decreases, whereas the amount
of dyes removed increases with the increase of the initial concentration of the dye
solutions. The results obtained shows that the percentage removal of dyes from aqueous
solution used in this study decreases from 94.9% to 80.3% for MB (Table 3), from 81.25%
to 74.42% for MV (Table 4), from 77.78% to 60.72% for AB (Table 5) and from 75.56% to
61.77% for AV (Table 6), when the initial concentration of dye solutions varied from
60 to 120mg/l in 180minutes of agitation time. The results are graphically depicted in
Figures 1– 4.
The results obtained shows that the percentage removal of dyes from dyeing
industrial effluent used in this study decreases from 45.07% to 34.44% for MB (Table 7),
from 76.74% to 69.39% for MV (Table 8), from 61.7% to 52.2% for AB (Table 9) and from
68.75% to 60.38% for AV (Table 10), when the initial concentration of dye solutions varied
from 60 to 100mg/l in 180minutes of agitation time. The results are graphically depicted in
Figures 5 – 8.
The results depicted in Tables 3 –10 and Figures 1– 8 indicates that the removal of
dyes increased progressively with the contact time for all the concentration of the dye
solutions used in this study. In addition, perusal of the results indicated that with increase in
dye concentration the percentage removal decreased, but the amount of dye adsorbed/unit
weight of the adsorbent increased for all the four dyes used in this study suggest that, the
dye removal using adsorption technique is concentration dependent. Further, it was
observed that the rate of adsorption was higher in the initial stages, because of the dye
uptake onto exterior surface, after that the dye molecules are entered into pores (interior
surface), relatively slow process (Ahmad and Kumar, 2010). This is due to an increase in
the driving force of the concentration gradient, as the initial dye concentration increases,
mass transfer driving force became larger and the interaction between the dye and
35
adsorbent was enhanced, hence resulting in higher adsorption capacity (Hameed et al.,2008; Aksu and Balibek, 2010; El-Syed, 2011; Han et al., 2011). The results obtained in
this study are in good agreement with the results reported on the extent of removal of
methylene blue dye on activated carbon (Sharma and Uma, 2010), on rice husk (Sharmaet al., 2010), on oak (Abd El-Latifa et al., 2010), on carbon nanotubes (Shahryari et al.,2010), on water weeds biomass (Tarawou and Horsfall, 2007) and on cashewnut shell
(Kumar et al., 2011).
This may be explained as, at a given constant adsorbent dosage, the decrease of the
adsorption with increase in initial concentration of dye solution may be due to the lack of
adsorbent surface area and the available sites for the adsorption becomes fewer for
adsorption and also due to nearly complete coverage of binding sites of the bioadsorbent
(Aksu and Balibek, 2010; Abechi et al., 2011; Satish Patil et al., 2011). In addition, the
formation of second layer of the dye molecules is highly hindered at higher initial
concentration of the dye, due to the repulsive interaction between adsorbed and
unadsorbed dye molecules present on the solid surface and in solution, respectively.
The curves were found to be continuous and smooth, leading to saturation, indicating the
possibilities of formation of monolayer coverage of dye on the outer surface of the
adsorbent (Theivarasu et al., 2010; Venckatesh et al., 2010).
36
Table 3
Adsorption of Methylene Blue Dye from Aqueous Solution with Variation ofInitial Concentration of Methylene Blue Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methylene Blue Dye in Percentage
60mg/l 80mg/l 100mg/l 120mg/l
10 83.8 78.3 75.7 51.6
20 88.0 79.1 77.7 56.1
30 88.9 84.5 82.4 57.3
40 89.8 86.5 86.2 61.8
50 90.7 88.4 87.2 64.3
60 91.5 89.2 87.8 66.9
90 92.3 89.9 88.5 70.1
120 93.2 90.7 90.5 74.5
150 94.0 92.2 91.2 78.9
180 94.9 93.0 92.6 80.3
37
Table 4
Adsorption of Methyl Violet Dye from Aqueous Solution with Variation ofInitial Concentration of Methyl Violet Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methyl Violet Dye in Percentage
60mg/l 80mg/l 100mg/l 120mg/l
10 59.38 45.71 43.90 41.86
20 62.50 48.78 48.57 44.19
30 65.63 57.14 53.66 46.51
40 68.75 60.00 58.54 48.84
50 71.88 65.71 63.41 55.81
60 74.47 68.57 65.85 60.47
90 75.38 71.43 70.73 62.79
120 78.13 74.29 73.17 67.44
150 78.46 77.14 75.61 72.09
180 81.25 80.00 78.05 74.42
38
Table 5
Adsorption of Acid Blue Dye from Aqueous Solution with Variation ofInitial Concentration of Acid Blue Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Blue Dye in Percentage
60mg/l 80mg/l 100mg/l 120mg/l
10 53.33 45.83 38.46 37.50
20 55.56 47.92 40.39 39.29
30 57.78 52.08 44.23 41.07
40 62.22 54.17 46.15 42.86
50 64.45 56.25 50.00 46.43
60 66.67 60.42 53.85 50.00
90 71.11 64.58 57.69 51.79
120 73.33 70.83 63.49 53.57
150 75.56 72.92 67.31 57.14
180 77.78 75.00 69.23 60.72
39
Table 6
Adsorption of Acid Violet Dye from Aqueous Solution with Variation ofInitial Concentration of Acid Violet Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Violet Dye in Percentage
60mg/l 80mg/l 100mg/l 120mg/l
10 37.78 35.72 34.21 29.42
20 42.22 39.10 38.47 32.35
30 46.67 42.48 40.10 35.29
40 53.33 44.86 42.74 41.18
50 57.78 47.62 47.37 44.12
60 60.00 52.38 50.00 47.06
90 66.67 57.14 52.63 50.00
120 71.11 61.91 55.27 52.94
150 73.33 66.67 57.89 55.88
180 75.56 69.05 63.16 61.77
40
Figure 1
Figure 2
50
60
70
80
90
100
0 20 40 60 80 100 120 140 160 180
Perc
enta
ge re
mov
al o
f dye
Time in minutes
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Variation of Initial Concentration of
Methylene Blue DyeSolution
60mg/l 80mg/l 100mg/l 120mg/l
40
50
60
70
80
90
0 20 40 60 80 100 120 140 160 180 200
Perc
enta
ge re
mov
al o
f dye
Time in minutes
Adsorption of Methyl Violet Dye from Aqueous Solution withVariation of Initial Concentration of
Methyl Violet Dye Solution
60mg/l 80mg/l 100mg/l 120mg/l
41
Figure 3
Figure 4
35
45
55
65
75
85
0 20 40 60 80 100 120 140 160 180 200
Perc
enta
ge re
mov
al o
f dye
Time in minutes
Adsorption of Acid Blue Dye from Aqueous Solution withVariation of Initial Concentration of
Acid Blue Dye Solution
60mg/l 80mg/l 100mg/l 120mg/l
20
30
40
50
60
70
80
0 50 100 150 200
Perc
enta
ge re
mov
al o
f dye
Time in minutes
Adsorption of Acid Violet Dye from Aqueous Solution withVariation of Initial Concentration of
Acid Violet Solution
120mg/l 100mg/l 80mg/l 60mg/l
42
Table 7
Adsorption of Methylene Blue Dye from Dyeing Industrial Effluent withVariation of Initial Concentration of Methylene Blue Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methylene Blue Dye in Percentage
60mg/l 80mg/l 100mg/l
10 35.21 31.36 26.11
20 35.91 32.00 27.78
30 36.62 32.64 28.33
40 38.03 33.28 29.44
50 38.73 33.92 30.00
60 40.14 36.48 31.11
90 41.55 37.76 32.22
120 42.25 40.60 32.78
150 43.66 42.24 33.89
180 45.07 43.52 34.44
43
Table 8
Adsorption of Methyl Violet Dye from Dyeing Industrial Effluent withVariation of Initial Concentration of Methyl Violet Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methyl Violet Dye in Percentage
60mg/l 80mg/l 100mg/l
10 44.19 43.78 42.86
20 46.51 45.65 43.46
30 48.84 47.83 46.93
40 51.16 50.00 48.98
50 60.47 58.87 53.06
60 63.28 61.04 57.14
90 65.12 63.22 60.26
120 72.09 69.57 65.31
150 74.42 71.74 67.35
180 76.74 75.10 69.39
44
Table 9
Adsorption of Acid Blue Dye from Dyeing Industrial Effluent with Variation ofInitial Concentration of Acid Blue Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Blue Dye in Percentage
60mg/l 80mg/l 100mg/l
10 38.5 35.3 28.6
20 41.0 37.2 30.8
30 43.2 38.8 34.2
40 45.2 40.7 36.6
50 47.4 42.9 40.0
60 49.6 45.5 43.5
90 53.1 47.9 45.9
120 55.8 51.0 47.4
150 58.9 53.2 49.1
180 61.7 56.0 52.2
45
Table 10
Adsorption of Acid Violet Dye from Dyeing Industrial Effluent with Variationof Initial Concentration of Acid Violet Dye Solution
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Violet Dye in Percentage
60mg/l 80mg/l 100mg/l
10 40.39 39.62 37.12
20 43.75 41.51 39.62
30 45.83 44.10 43.75
40 50.00 49.02 45.28
50 52.08 50.94 47.17
60 58.33 54.90 48.56
90 60.42 56.86 50.94
120 62.50 58.82 52.83
150 64.58 60.78 56.60
180 68.75 62.75 60.38
46
Figure 5
Figure 6
20
25
30
35
40
45
50
0 20 40 60
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methylene Blue Dye from Dyeing IndustrialEffluent with Variation of Initial Concentration of
Methylene Blue Dye Solution
60mg/l
40
50
60
70
80
0 20 40 60
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methyl Violet Dye from Dyeing IndustrialEffluent with Variation of Initial Concentration of
Methyl Violet Dye Solution
60mg/l
46
Figure 5
Figure 6
60 80 100 120 140 160 180 200
Time in minutes
Adsorption of Methylene Blue Dye from Dyeing IndustrialEffluent with Variation of Initial Concentration of
Methylene Blue Dye Solution
80mg/l 100mg/l
60 80 100 120 140 160 180 200Time in minutes
Adsorption of Methyl Violet Dye from Dyeing IndustrialEffluent with Variation of Initial Concentration of
Methyl Violet Dye Solution
80mg/l 100mg/l
46
Figure 5
Figure 6
200
200
47
Figure 7
Figure 8
20
30
40
50
60
70
0 50
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Blue Dye from Dyeing Industrial Effluentwith Variation of Initial Concentration of
Acid Blue Dye Solution
60mg/l
20
30
40
50
60
70
80
0 50
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Violet Dye from Dyeing Industrial Effluentwith Variation of Initial Concentration of
Acid Violet Dye Solution
60mg/l
47
Figure 7
Figure 8
100 150 200Time in minutes
Adsorption of Acid Blue Dye from Dyeing Industrial Effluentwith Variation of Initial Concentration of
Acid Blue Dye Solution
60mg/l 80mg/l 100mg/l
100 150 200Time in minutes
Adsorption of Acid Violet Dye from Dyeing Industrial Effluentwith Variation of Initial Concentration of
Acid Violet Dye Solution
60mg/l 80mg/l 100mg/l
47
Figure 7
Figure 8
200
200
48
4.3 Effect of pH on Dye Removal
The pH of the dye solution plays an important role in the adsorption process,
particularly in the adsorption capacity, influencing the surface charge of the adsorbent, the
degree of ionisation of the dye present in the solution and the dissociation of functional
groups on the active sites of the adsorbent (Aksu and Balibek, 2010; Saeed et al., 2010;
Chakraborty et al., 2011). The hydrogen and hydroxyl ions are adsorbed quite strongly,
and therefore, the adsorption of other ions is affected by the pH of the solution. The anions
are adsorbed by the adsorbent at lower pH due to the presence of H+ ions and at higher
pH, cations are adsorbed due to the negatively charged surface sites (Emrah Bulut, 2008).
The role of hydrogen ion concentration is studied for the adsorption of the dyes used
in this study by varying the pH (from pH 5 to pH 9) using 0.1N H2SO4 or 0.1N NaOH.
To study the effect of pH, 100ml of the dye solutions containing 100mg of the dye are taken
in Pyrex bottles containing 500mg of the adsorbent BGA at 32 ± 2ºC and batch mode
adsorption experiments performed. The experimental results observed for the effect of
variation of pH on percentage removal of dyes from the aqueous solution are shown in
Tables 11 – 14.
The percentage removal of Methylene Blue dye (from 86.4% to 92.6%) and Acid
Violet dye (from 54.76% to 69.05%) increased, when the pH is varied from 5.0 ± 0.2 to
7.0 ± 0.2 in 180minutes of agitation time and then decreases with increase in pH above
7.0 ± 0.2. The graphical representations of the adsorption of Methylene Blue and Acid
Violet dyes from aqueous solution with the variation of pH are shown in Figures 9 & 10
Lower adsorption of Methylene Blue and Acid Violet dyes at acidic pH, may be due to
the presence of excess H+ ions competing with dye cations for the adsorption sites
(El-Sayed, 2011; Guimaraes Gusmao et al., 2012). At alkaline pH, the surface of the
adsorbent acquires negative charge due to the adsorption of OH- ions and the negatively
charged surface of the adsorbent repelled the dye species and thus adsorption of the dyes
decreases.
In the case of Methyl Violet and Acid Blue dyes, the percentage removal of the dyes
increased from 70.73% to 78.05% for MV and from 51.92% to 69.23% for AB with the
increase in pH of the dye solution from 5.0 ± 0.2 to 7.0 ± 0.2 in 180minutes of agitation
time. Further increases of pH from 7.0 ± 0.2 to 9.0 ± 0.2, adsorption of the dyes are
49
insignificant and almost kept constant. Similar results were observed by Aksu and Balibek,
(2010); Yi Liu et al., (2010); Deng et al., (2011); Chakraborty et al., (2011). The graphical
representations of the adsorption of Methyl Violet and Acid Blue from aqueous solution with
pH variation are shown in Figures 11 & 12
As pH increases from 5 to 7, the charge density of the dye solution decreases,
so that electrostatic repulsion between the positively charged dye molecules and
the surface of the adsorbent is lowered. It results in an increase in the adsorption of the dye
(Mittal et al., 2010; Saeed et al., 2010; Yonghui Lin et al., 2011; Yu et al., 2012).pH is, also, known to affect the structural stability of the dye and therefore, its colour
intensity also affect. It is obviously observed that the dyes MV and AB dyes used in this
study are not stable to combine with hydroxyl ion in the solution and generate emulsion
precipitate when pH > 7, thus, original pH 7 for MV and AB dyes are considered as
optimum pH for the dye adsorption. Similar results were observed by Unuabonah et al.,(2009); Saeed et al., (2010); Abd El – Latifa et al., (2010); Han et al., (2011); Ma et al.,(2012).
50
Table 11
Adsorption of Methylene Blue Dye from Aqueous Solution with pH Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye Solution : 100mg/l
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methylene Blue Dye in Percentage
pH 5 pH 6 pH 7 pH 8 pH 9
10 66.2 73.3 75.7 67.6 63.5
20 68.9 76.4 77.7 75.7 76.8
30 69.6 80.7 82.4 81.8 80.7
40 73.7 82.7 86.5 84.5 82.2
50 75.0 83.4 87.2 85.8 83.4
60 76.4 84.7 87.8 86.5 84.7
90 81.8 85.3 88.5 87.8 85.9
120 84.5 86.7 90.5 88.5 86.6
150 85.8 87.3 91.2 89.2 87.3
180 86.4 88.5 92.6 91.6 88.5
51
Table 12
Adsorption of Acid Violet Dye from Aqueous Solution with pH Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye solution : 100mg/l
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Violet Dye in Percentage
pH 5 pH 6 pH 7 pH 8 pH 9
10 26.19 33.33 35.72 33.33 19.05
20 28.57 35.72 38.10 35.72 21.43
30 30.97 38.10 40.48 38.10 23.81
40 35.72 42.86 45.24 40.48 26.19
50 38.10 45.24 47.62 45.24 28.57
60 42.86 47.62 52.38 47.62 33.33
90 45.24 49.03 57.14 52.38 35.72
120 47.62 52.38 61.91 57.14 38.10
150 52.38 54.76 66.67 54.76 40.48
180 54.76 57.14 69.05 64.43 47.62
52
Figure 9
Figure 10
0
20
40
60
80
100
10 20 30
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methylene Blue Dye from Aqueous Solutionwith pH Variation
pH 5 pH 6
10
20
30
40
50
60
70
80
10 20 30
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Violet Dye from Aqueous Solutionwith pH Variation
pH 5 pH 6
52
Figure 9
Figure 10
40 50 60 90 120 150 180Time in minutes
Adsorption of Methylene Blue Dye from Aqueous Solutionwith pH Variation
pH 6 pH 7 pH 8 pH 9
40 50 60 90 120 150 180Time in minutes
Adsorption of Acid Violet Dye from Aqueous Solutionwith pH Variation
pH 6 pH 7 pH 8 pH 9
52
Figure 9
Figure 10
180
180
53
Table 13Adsorption of Methyl Violet Dye from Aqueous Solution with pH Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye solution : 100mg/l
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methyl Violet Dye in Percentage
pH 5 pH 6 pH 7 pH 8 pH 9
10 39.02 41.46 43.90 43.90 43.90
20 41.46 43.90 48.78 48.78 48.78
30 43.90 51.22 53.66 53.66 53.66
40 51.22 53.66 58.54 58.54 58.54
50 53.66 58.54 63.41 63.41 63.41
60 58.44 60.98 65.85 65.85 65.85
90 60.98 63.41 70.73 70.73 70.73
120 65.85 68.29 73.17 73.17 73.17
150 68.29 70.73 75.61 75.61 75.61
180 70.73 73.17 78.05 78.05 78.05
54
Table 14
Adsorption of Acid Blue Dye from Aqueous Solution with pH Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye solution : 100mg/l
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Blue Dye in Percentage
pH 5 pH 6 pH 7 pH 8 pH 9
10 30.77 36.54 38.46 38.46 38.46
20 32.69 38.46 40.39 40.39 40.39
30 34.62 40.39 44.23 44.23 44.23
40 36.54 42.31 46.15 46.15 46.15
50 40.39 44.23 50.00 50.00 50.00
60 42.31 46.15 53.85 53.85 53.85
90 44.23 48.08 57.69 57.69 57.69
120 46.15 51.92 63.49 63.49 63.49
150 48.08 53.55 67.31 67.31 67.31
180 51.92 57.69 69.23 69.23 69.23
55
Figure 11
Figure 12
30
40
50
60
70
80
10 20 30
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methyl Violet Dye from Aqueous Solutionwith pH Variation
pH 5 pH 6
20
30
40
50
60
70
10 20 30
Perc
ntag
e re
mov
al o
f dye
Adsorption of Acid Blue Dye from Aqueous Solutionwith pH Variation
pH 5 pH 6
55
Figure 11
Figure 12
40 50 60 90 120 150 180Time in minutes
Adsorption of Methyl Violet Dye from Aqueous Solutionwith pH Variation
pH 6 pH 7 pH 8 pH 9
40 50 60 90 120 150 180Time in minutes
Adsorption of Acid Blue Dye from Aqueous Solutionwith pH Variation
pH 6 pH 7 pH 8 pH 9
55
Figure 11
Figure 12
180
Adsorption of Methyl Violet Dye from Aqueous Solutionwith pH Variation
180
56
4.4 Effect of Adsorbent Dosage on Dye Removal
Adsorbent dosage is an important parameter that strongly influences the adsorption
process by affecting the adsorption capacity of the adsorbent (Chakraborty et al., 2011).The effect of adsorbent dosage is investigated for the removal of Methylene Blue, Methyl
Violet, Acid Blue and Acid Violet dyes from aqueous solution by varying the dosage of the
adsorbent BGA from 200mg to 500mg. Batch mode experiments are carried out by using
100ml of dye solution containing 100mgdye/l at 32 ± 2ºC and at pH 7.0 ± 0.2 by varying the
adsorbent dosage. It is observed that the percentage removal of dyes increased, when the
adsorbent dosage is varied from 200mg to 500mg (for Methylene Blue from 85.1% to
92.6%, for Methyl Violet from 63.41% to 78.05%, for Acid Blue from 51.92% to 69.23% and
for Acid Violet from 42.86% to 69.05%). The results obtained are shown in Tables 15 – 18
and graphically represented in Figures 13 – 16.
The increase in the percentage removal of the dyes with adsorbent dosage could be
attributed to an increase in the surface area of the adsorbent, augmenting the more
number of adsorption sites available for adsorption (Subha and Namasivayam, 2009;Renugadevi et al., 2009b). Similar reports were observed for the adsorption of Direct Red-
28 onto Punica Granatum Carbon (Venckatesh et al., 2010) and for the adsorption of
Methylene Blue onto biomass material Lotus Leaf (Han et al., 2011).
57
Table 15
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Adsorbent Dosage Variation
Conditions:
Concentration of dye solution : 100mg/l
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methylene Blue Dye in Percentage
200mg 300mg 400mg 500mg
10 57.8 66.2 69.6 75.7
20 63.4 68.9 73.7 77.7
30 67.6 69.6 75.0 82.4
40 68.9 73.7 75.7 86.5
50 69.6 75.0 81.8 87.2
60 73.7 75.7 83.8 87.8
90 75.0 81.8 85.8 88.5
120 75.7 83.8 86.5 90.5
150 81.8 85.8 87.8 91.2
180 85.1 86.5 88.5 92.6
58
Table 16
Adsorption of Methyl Violet Dye from Aqueous Solutionwith Adsorbent Dosage Variation
Conditions:
Concentration of dye solution : 100mg/l
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Methyl Violet Dye in Percentage
200mg 300mg 400mg 500mg
10 36.57 39.02 41.46 43.90
20 42.73 43.90 46.34 48.78
30 46.34 48.78 51.22 53.66
40 48.78 53.66 56.10 58.54
50 51.22 58.54 60.98 63.41
60 53.66 60.98 63.41 65.85
90 56.10 63.41 68.29 70.73
120 58.54 65.85 70.73 73.17
150 60.98 68.29 73.17 75.61
180 63.41 70.73 75.61 78.05
59
Table 17
Adsorption of Acid Blue Dye from Aqueous Solutionwith Adsorbent Dosage Variation
Conditions:
Concentration of dye solution : 100 mg/l
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Blue Dye in Percentage
200mg 300mg 400mg 500mg
10 30.77 32.69 36.54 38.46
20 32.69 34.62 38.46 41.39
30 34.62 36.54 40.39 44.23
40 36.54 40.39 42.31 47.15
50 40.39 42.31 44.23 50.00
60 42.31 44.23 46.15 53.85
90 44.23 46.15 48.08 57.69
120 46.15 48.08 51.92 61.49
150 48.08 51.92 53.55 65.31
180 51.92 54.17 57.69 69.23
60
Table 18
Adsorption of Acid Violet Dye from Aqueous Solutionwith Adsorbent Dosage Variation
Conditions:
Concentration of dye solution : 100mg/l
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Time inminutes
Removal of Acid Violet Dye in Percentage
200mg 300mg 400mg 500mg
10 17.00 19.0 26.19 35.72
20 19.05 21.43 29.00 38.10
30 23.81 24.57 30.95 40.48
40 24.57 26.19 33.33 42.86
50 26.19 28.57 35.72 47.62
60 33.33 35.72 38.10 52.38
90 35.72 38.10 42.86 57.14
120 38.10 42.86 47.38 61.91
150 40.48 47.38 52.38 66.67
180 42.86 52.38 54.76 69.05
61
Figure 13
Figure 14
50
60
70
80
90
100
0 20 40 60
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Adsorbent Dosage Variation
200mg
30
40
50
60
70
80
90
0 20 40 60
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methyl Violet Dye from Aqueous Solutionwith Adsorbent Dosage Variation
200mg
61
Figure 13
Figure 14
60 80 100 120 140 160 180 200Time in minutes
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Adsorbent Dosage Variation
300mg 400mg 500mg
60 80 100 120 140 160 180 200Time in minutes
Adsorption of Methyl Violet Dye from Aqueous Solutionwith Adsorbent Dosage Variation
300mg 400mg 500mg
61
Figure 13
Figure 14
200
200
Adsorption of Methyl Violet Dye from Aqueous Solutionwith Adsorbent Dosage Variation
62
Figure 15
Figure 16
25
35
45
55
65
75
0 20 40 60
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Blue Dye from Aqueous Solutionwith Adsorbent DosageVariation
200mg
0
20
40
60
80
0 20 40 60
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Violet Dye from Aqueous Solution withAdsorbent Dosage Variation
200mg
62
Figure 15
Figure 16
60 80 100 120 140 160 180 200
Time in minutes
Adsorption of Acid Blue Dye from Aqueous Solutionwith Adsorbent DosageVariation
300mg 400mg 500mg
60 80 100 120 140 160 180 200Time in minutes
Adsorption of Acid Violet Dye from Aqueous Solution withAdsorbent Dosage Variation
300mg 400mg 500mg
62
Figure 15
Figure 16
200
200
Adsorption of Acid Violet Dye from Aqueous Solution withAdsorbent Dosage Variation
63
4.5 Effect of Temperature on Dye Removal
The effect of temperature on adsorption of Methylene Blue, Methyl Violet, Acid Blue
and Acid Violet dyes are studied by varying the temperature 22˚C, 32˚C and 42˚C. Batch
mode experiments are carried out by using the 100ml of dye solution containing 100mg dye
per litre at pH 7.0 ± 0.2 using 500mg of the adsorbent BGA. It is observed that the
percentage removal of dyes increased, when the temperature is varied from 22˚C to 42˚C(for Methylene Blue from 87.8% to 93.4%, for Methyl Violet from 73.17% to 85.37%, for
Acid Blue from 51.92% to 75.00% and for Acid Violet from 54.76% to 73.81%).
The enhancement in adsorption with temperature may be due to the increase in the
mobility of the dye molecule with increase in their kinetic energy (Renugadevi et al.,
2009b; Ahmad and Kumar, 2010). The results obtained are shown in Tables 19 - 22 and
graphically represented in Figures 17 - 20. Similar results have been reported for the
adsorption of Crystal Violet on grape fruit peel (Saeed et al., 2010) and on oak saw dust
(Abd El – Latifa et al., 2010).
64
Table 19
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Temperature Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye solution : 100mg/l
pH : 7.0 ± 0.2
Time inminutes
Removal of Methylene Blue Dye in Percentage
22˚C 32˚C 42˚C
10 69.6 75.7 84.5
20 71.0 77.7 85.8
30 73.7 82.4 86.5
40 75.0 86.5 87.8
50 75.7 87.2 88.5
60 81.8 87.8 89.1
90 85.1 88.5 90.5
120 85.8 90.5 91.2
150 86.5 91.2 91.9
180 87.8 92.6 93.4
65
Table 20
Adsorption of Methyl Violet Dye from Aqueous Solutionwith Temperature Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye solution : 100mg/l
pH : 7.0 ± 0.2
Time inminutes
Removal of Methyl Violet Dye in Percentage
22˚C 32˚C 42˚C
10 41.46 43.90 48.78
20 43.90 48.78 51.22
30 48.78 53.66 56.10
40 51.22 58.54 60.98
50 53.66 63.41 65.85
60 56.10 65.85 73.17
90 60.98 70.73 75.61
120 65.86 73.17 78.05
150 70.73 75.61 80.49
180 73.17 78.05 85.37
66
Table 21
Adsorption of Acid Blue Dye from Aqueous Solutionwith Temperature Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye solution : 100mg/l
pH : 7.0 ± 0.2
Time inminutes
Removal of Acid Blue Dye in Percentage
22˚C 32˚C 42˚C
10 30.77 38.46 50.00
20 32.69 40.39 51.92
30 32.69 44.23 53.85
40 34.62 46.15 55.77
50 36.54 50.00 59.62
60 42.31 53.85 63.46
90 44.23 57.69 65.39
120 48.08 63.49 69.23
150 50.00 67.31 71.15
180 51.92 69.23 75.00
67
Table 22
Adsorption of Acid Violet Dye from Aqueous Solutionwith Temperature Variation
Conditions:
Adsorbent Dosage : 500mg
Concentration of dye solution : 100mg/l
pH : 7.0 ± 0.2
Time inminutes
Removal of Acid Violet Dye in Percentage
22˚C 32˚C 42˚C
10 23.81 35.72 38.10
20 26.19 38.10 40.40
30 28.57 40.48 42.86
40 33.33 42.86 47.62
50 35.72 47.62 52.38
60 40.48 52.38 54.76
90 42.86 57.14 61.91
120 47.62 61.91 64.43
150 52.38 66.67 69.05
180 54.76 69.05 73.81
68
Figure 17
Figure 18
50
60
70
80
90
100
10 20 30
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Temperature Variation
22◦C
0
20
40
60
80
10 20 30
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methyl Violet Dye from Aqueous Solutionwith Temperature Variation
22˚C
68
Figure 17
Figure 18
40 50 60 90 120 150 180
Time in minutes
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Temperature Variation
32◦C 42◦C
40 50 60 90 120 150 180Time in minutes
Adsorption of Methyl Violet Dye from Aqueous Solutionwith Temperature Variation
32˚C 42˚C
68
Figure 17
Figure 18
180
Adsorption of Methylene Blue Dye from Aqueous Solutionwith Temperature Variation
180
69
Figure 19
Figure 20
0
20
40
60
80
10 20 30
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Blue Dye from Aqueous Solutionwith Temperature Variation
22◦C
0
20
40
60
80
10 20 30
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Violet Dye from Aqueous Solutionwith Temperature Variation
22˚C
69
Figure 19
Figure 20
40 50 60 90 120 150 180Time in minutes
Adsorption of Acid Blue Dye from Aqueous Solutionwith Temperature Variation
32◦C 42◦C
40 50 60 90 120 150 180Time in minutes
Adsorption of Acid Violet Dye from Aqueous Solutionwith Temperature Variation
32˚C 42˚C
69
Figure 19
Figure 20
180
180
70
4.6 Adsorption of Dyes from Dyeing Industrial Effluent
The textile dye effluents are collected from a common effluent treatment plant in
Tiruppur, the texcity of Tamilnadu, India. Batch mode experiments are carried out at pH
7.0 ± 0.2 and at 32°C using 500mg of BGA and the contact time is maintained as
180minutes.
Blue-Green Algae was found to be efficient in the removal of the dyes from the
dyeing industrial effluents and the experimental work reported lesser percentage removal of
dyes from the effluents, compared to that of aqueous solutions. This may be due to the
adsorption of other pollutants (Sharma and Kaur, 1997) present in the dyeing industrial
effluent on the surface of the adsorbent BGA. The data for the adsorption of dyes from
aqueous solution and from dyeing industrial effluent using BGA are given in
Figures 21 - 24.
Pollutants present in the Dyeing Industrial EffluentName of the dyeingindustrial effluent
Organic Pollutants InOrganic Pollutants
Methylene Blue,Methyl Violet,Acid Blue andAcid Violet Dyes
Detergents, phenols, organic matterand cellulose fibres
Hardness, alkalinity, Iron,suspended solids, cyanide,thiocyanate, sulphates,carbonates and chlorides,
10 20from aqueous solution 75.7 77.7from effluent 35.21 35.91
20
40
60
80
100
Perc
enta
ge re
mov
al o
f dye
Adsorption of Methylene Blue Dye from Aqueous Solutionand from Dyeing Industrial Effluent using BGA
70
4.6 Adsorption of Dyes from Dyeing Industrial Effluent
The textile dye effluents are collected from a common effluent treatment plant in
Tiruppur, the texcity of Tamilnadu, India. Batch mode experiments are carried out at pH
7.0 ± 0.2 and at 32°C using 500mg of BGA and the contact time is maintained as
180minutes.
Blue-Green Algae was found to be efficient in the removal of the dyes from the
dyeing industrial effluents and the experimental work reported lesser percentage removal of
dyes from the effluents, compared to that of aqueous solutions. This may be due to the
adsorption of other pollutants (Sharma and Kaur, 1997) present in the dyeing industrial
effluent on the surface of the adsorbent BGA. The data for the adsorption of dyes from
aqueous solution and from dyeing industrial effluent using BGA are given in
Figures 21 - 24.
Pollutants present in the Dyeing Industrial EffluentName of the dyeingindustrial effluent
Organic Pollutants InOrganic Pollutants
Methylene Blue,Methyl Violet,Acid Blue andAcid Violet Dyes
Detergents, phenols, organic matterand cellulose fibres
Hardness, alkalinity, Iron,suspended solids, cyanide,thiocyanate, sulphates,carbonates and chlorides,
20 30 40 50 60 90 120 150 180
77.7 82.4 86.5 87.2 87.8 88.5 90.5 91.2 92.635.91 36.62 38.03 38.73 40.14 41.55 42.25 43.66 45.07
Adsorption of Methylene Blue Dye from Aqueous Solutionand from Dyeing Industrial Effluent using BGA
70
4.6 Adsorption of Dyes from Dyeing Industrial Effluent
The textile dye effluents are collected from a common effluent treatment plant in
Tiruppur, the texcity of Tamilnadu, India. Batch mode experiments are carried out at pH
7.0 ± 0.2 and at 32°C using 500mg of BGA and the contact time is maintained as
180minutes.
Blue-Green Algae was found to be efficient in the removal of the dyes from the
dyeing industrial effluents and the experimental work reported lesser percentage removal of
dyes from the effluents, compared to that of aqueous solutions. This may be due to the
adsorption of other pollutants (Sharma and Kaur, 1997) present in the dyeing industrial
effluent on the surface of the adsorbent BGA. The data for the adsorption of dyes from
aqueous solution and from dyeing industrial effluent using BGA are given in
Figures 21 - 24.
Pollutants present in the Dyeing Industrial EffluentName of the dyeingindustrial effluent
Organic Pollutants InOrganic Pollutants
Methylene Blue,Methyl Violet,Acid Blue andAcid Violet Dyes
Detergents, phenols, organic matterand cellulose fibres
Hardness, alkalinity, Iron,suspended solids, cyanide,thiocyanate, sulphates,carbonates and chlorides,
180
92.645.07
Adsorption of Methylene Blue Dye from Aqueous Solutionand from Dyeing Industrial Effluent using BGA
71
Figure 21
Figure 22
Figure 23
10from aqueous solution 43.9 48.5from effluent 42.8 43.4
20
40
60
80Pe
rcen
tage
rem
oval
of d
ye
Adsorption of Methyl Violet Dye from Aqueous Solution andfrom Dyeing Industrial Effluent using BGA
10
from aqueous solution 38.4from effluent 28.6
20
40
60
80
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Blue Dye from Aqueous Solution andfrom Dyeing Industrial Effluent using BGA
71
Figure 21
Figure 22
Figure 23
20 30 40 50 60 90 120 15048.5 53.6 58.5 63.4 65.8 70.7 73.1 75.643.4 46.9 48.9 53.0 57.1 60.2 65.3 67.3
Adsorption of Methyl Violet Dye from Aqueous Solution andfrom Dyeing Industrial Effluent using BGA
10 20 30 40 50 60 90 120
150
38.4 40.3 44.2 46.1 50 53.8 57.6 63.4 67.328.6 30.8 34.2 36.6 40 43.5 45.9 47.4 49.1
Adsorption of Acid Blue Dye from Aqueous Solution andfrom Dyeing Industrial Effluent using BGA
71
Figure 21
Figure 22
Figure 23
150 18075.6 78.067.3 69.3
180
67.3 69.249.1 52.2
72
Figure 24
4.7 Efficiency of Blue-Green Algae in the Removal of Dyes by Adsorption
The percentage removal of Methylene Blue, Methyl Violet, Acid Blue and Acid Violet
dyes from aqueous solutions and also from dyeing industrial effluents using the adsorbents
Blue-Green Algae and Commercial Activated Carbon are investigated. Batch mode
experiments are carried out by using the 100ml of dye solution containing 100mg of
dye/litre at 32 ± 2º C and at pH 7.0 ± 0.2 with 100mg of the adsorbents. The obtained
results are given in Tables 23 - 26 and Figures 25 - 28.
Removal efficiency of the adsorbent Blue-Green Algae (BGA) is an important
aspect, as it needs to be compared with the Commercial Activated Carbon (CAC).
Commercial Activated Carbon has greater percentage removal of the dyes from aqueous
solution and also from dyeing industrial effluents, compared to that of Blue-Green Algae,
which could be attributed due to the greater surface area of the adsorbent CAC (Surface
area of CAC is 1021m2/g). However removal of dyes by adsorption using Commercial
Activated Carbon is quite expensive. Though the percentage removal of dyes from
aqueous solution and also from dyeing industrial effluents using Blue-Green Algae by
adsorption is less compare to that of CAC due to its lesser surface area (Surface area of
BGA is 479m2/g), it is advantageous, since BGA is available in large quantities as natural
biowaste and cost effective.
10from aqueous solution 34.2 38.4from effluent 27.1 29.6
20
30
40
50
60
70
Perc
enta
ge re
mov
al o
f dye
Adsorption of Acid Violet Dye from Aqueous Solution andfrom Dyeing Industrial Effluent using BGA
72
Figure 24
4.7 Efficiency of Blue-Green Algae in the Removal of Dyes by Adsorption
The percentage removal of Methylene Blue, Methyl Violet, Acid Blue and Acid Violet
dyes from aqueous solutions and also from dyeing industrial effluents using the adsorbents
Blue-Green Algae and Commercial Activated Carbon are investigated. Batch mode
experiments are carried out by using the 100ml of dye solution containing 100mg of
dye/litre at 32 ± 2º C and at pH 7.0 ± 0.2 with 100mg of the adsorbents. The obtained
results are given in Tables 23 - 26 and Figures 25 - 28.
Removal efficiency of the adsorbent Blue-Green Algae (BGA) is an important
aspect, as it needs to be compared with the Commercial Activated Carbon (CAC).
Commercial Activated Carbon has greater percentage removal of the dyes from aqueous
solution and also from dyeing industrial effluents, compared to that of Blue-Green Algae,
which could be attributed due to the greater surface area of the adsorbent CAC (Surface
area of CAC is 1021m2/g). However removal of dyes by adsorption using Commercial
Activated Carbon is quite expensive. Though the percentage removal of dyes from
aqueous solution and also from dyeing industrial effluents using Blue-Green Algae by
adsorption is less compare to that of CAC due to its lesser surface area (Surface area of
BGA is 479m2/g), it is advantageous, since BGA is available in large quantities as natural
biowaste and cost effective.
20 30 40 50 60 90 120 15034.2 38.4 40.1 42.7 47.3 50 52.6 55.2 57.827.1 29.6 33.7 35.2 37.1 38.5 40.9 42.8 46.6
Adsorption of Acid Violet Dye from Aqueous Solution andfrom Dyeing Industrial Effluent using BGA
72
Figure 24
4.7 Efficiency of Blue-Green Algae in the Removal of Dyes by Adsorption
The percentage removal of Methylene Blue, Methyl Violet, Acid Blue and Acid Violet
dyes from aqueous solutions and also from dyeing industrial effluents using the adsorbents
Blue-Green Algae and Commercial Activated Carbon are investigated. Batch mode
experiments are carried out by using the 100ml of dye solution containing 100mg of
dye/litre at 32 ± 2º C and at pH 7.0 ± 0.2 with 100mg of the adsorbents. The obtained
results are given in Tables 23 - 26 and Figures 25 - 28.
Removal efficiency of the adsorbent Blue-Green Algae (BGA) is an important
aspect, as it needs to be compared with the Commercial Activated Carbon (CAC).
Commercial Activated Carbon has greater percentage removal of the dyes from aqueous
solution and also from dyeing industrial effluents, compared to that of Blue-Green Algae,
which could be attributed due to the greater surface area of the adsorbent CAC (Surface
area of CAC is 1021m2/g). However removal of dyes by adsorption using Commercial
Activated Carbon is quite expensive. Though the percentage removal of dyes from
aqueous solution and also from dyeing industrial effluents using Blue-Green Algae by
adsorption is less compare to that of CAC due to its lesser surface area (Surface area of
BGA is 479m2/g), it is advantageous, since BGA is available in large quantities as natural
biowaste and cost effective.
150 18057.8 63.146.6 50.3
73
Percentage removal of dyes from the dyeing industrial effluents, compared to that of
aqueous solutions are lesser with both the adsorbents CAC and BGA, this may be due to
the adsorption of other pollutants present in the dyeing industrial effluents on the surface of
the adsorbents CAC and BGA.
Table 23
Adsorption of Methylene Blue Dye from Aqueous Solution and fromDyeing Industrial Effluent using Blue-Green Algae and
Commercial Activated Carbon
Conditions:
Adsorbent Dosage : 100mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes
Removal of MB Dye inPercentage using
BGA
Removal of MB Dye inPercentage using
CACFrom Aqueous
SolutionFrom
EffluentFrom Aqueous
SolutionFrom
Effluent
10 31.1 19.7 66.2 38.0
20 33.1 20.4 68.9 38.7
30 33.8 21.1 69.6 40.1
40 35.1 21.8 70.9 41.5
50 41.2 23.2 73.6 42.3
60 42.6 25.4 73.9 43.7
90 43.2 26.8 77.0 45.1
120 43.9 27.5 77.5 47.2
150 44.6 28.9 81.1 51.4
180 45.3 31.0 82.4 54.2
74
Table 24
Adsorption of Methyl Violet Dye from Aqueous Solution and from DyeingIndustrial Effluent using Blue-Green Algae and
Commercial Activated CarbonConditions:
Adsorbent Dosage : 100mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes
Removal of MV Dye inPercentage using
BGARemoval of MV Dye in
Percentage usingCAC
From AqueousSolution
FromEffluent
From AqueousSolution
FromEffluent
10 36.6 19.5 41.5 26.8
20 41.5 22.0 43.9 29.3
30 43.9 24.4 48.8 31.7
40 46.3 26.8 51.2 34.1
50 48.8 29.3 53.7 36.6
60 51.2 34.7 56.1 41.5
90 53.4 36.6 60.9 46.3
120 55.0 39.0 65.9 51.2
150 56.1 41.5 68.3 53.7
180 58.5 43.9 70.7 56.1
75
Table 25
Adsorption of Acid Blue Dye from Aqueous Solution and from DyeingIndustrial Effluent using Blue-Green Algae and
Commercial Activated CarbonConditions:
Adsorbent Dosage : 100mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes
Removal of AB Dye inPercentage using
BGA
Removal of AB Dye inPercentage using
CAC
From AqueousSolution
FromEffluent
From AqueousSolution
FromEffluent
10 7.7 3.8 26.9 13.5
20 9.6 5.8 28.8 15.4
30 13.5 7.7 32.7 17.3
40 19.2 11.5 34.6 21.2
50 23.1 13.5 38.5 23.1
60 26.9 17.3 40.4 26.9
90 32.7 21.2 44.2 28.8
120 34.6 23.1 46.2 32.7
150 38.5 25.0 50.0 36.5
180 40.4 26.9 53.8 38.5
76
Table 26
Adsorption of Acid Violet Dye from Aqueous Solution and fromDyeing Industrial Effluent using Blue-Green Algae and
Commercial Activated CarbonConditions:
Adsorbent Dosage : 100mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes
Removal of AV Dye inPercentage using
BGA
Removal of AV Dye inPercentage using
CAC
From AqueousSolution
FromEffluent
From AqueousSolution
FromEffluent
10 9.5 4.8 23.8 9.5
20 11.9 7.1 28.6 11.9
30 16.7 9.5 31.0 16.7
40 19.0 11.9 33.3 21.4
50 21.4 14.3 35.7 23.8
60 26.2 16.7 38.1 26.2
90 31.0 19.0 42.9 28.6
120 35.7 21.4 45.2 31.0
150 38.1 23.8 47.6 35.7
180 40.5 26.2 50.0 38.1
77
Figure 25
Figure 26
Removal of Dyes from Aqueous Solution using BGA
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
Removal of Dyes from Aqueous Solution using CAC
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
77
Figure 25
Figure 26
Methylene Blue45.3%
Methyl Violet58.5%
Acid Blue40.4%
Acid Violet40.5%
Removal of Dyes from Aqueous Solution using BGA
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
Methylene Blue82.4%
Methyl Violet70.7%
Acid Blue53.8%
Acid Violet50.0%
Removal of Dyes from Aqueous Solution using CAC
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
77
Figure 25
Figure 26
78
Figure 27
Figure 28
Removal of Dyes from Dyeing Industrial Effluentusing BGA
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
Removal of Dyes from Dyeing Industrial Effluentusing CAC
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
78
Figure 27
Figure 28
Methylene Blue31.0%
Methyl Violet43.9%
Acid Blue26.9%
Acid Violet26.2%
Removal of Dyes from Dyeing Industrial Effluentusing BGA
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
Methylene Blue54.2%
Methyl Violet56.1%
Acid Blue38.5%
Acid Violet38.1%
Removal of Dyes from Dyeing Industrial Effluentusing CAC
Conditions:
Adsorbent Dosage : 100mgpH : 7.0 ± 0.2Temperature : 32 ± 2˚CConcentration ofDye Solution : 100mg/lContact Time : 180minutes
78
Figure 27
Figure 28
79
4.8 Kinetics of Adsorption
The study of adsorption kinetics is significant as it provides valuable insights into the
reaction path ways and into the mechanism of the reactions. The adsorption process is
usually demonstrated by four steps:
1. Transport of adsorbate from bulk solution to the liquid film or boundary layer
surrounding the adsorbent.
2. Transport of adsorbate from the boundary film to the external surface of the adsorbent
(surface diffusion).
3. Transfer of the adsorbate from the surface to the intraparticle active sites (pore
diffusion).
4. Adsorption of dyes by the active sites of adsorbent.
The slowest of these determines the overall rate of the adsorption processes. The
first step is not involved with adsorbent and fourth step is a very rapid process, they do not
belong to the rate controlling steps. Therefore, the rate controlling steps mainly depend on
step 2 and step 3 either surface diffusion or pore diffusion (Theydan et al., 2012).
4.8.1 Lagergren Rate Equation
The Lagergren rate constant for the adsorption of the Methylene Blue, Methyl Violet,
Acid Blue and Acid Violet dyes from aqueous solution and from dyeing industrial effluent on
the adsorbent BGA is determined using Lagergren equation (Lagergren, 1898;Renugadevi et al., 2010).
log (qe- q) = log qe – (Ka / 2.303) x twhere
q - amount of dye adsorbed (mg/g) by the adsorbent at time ‘t’
qe - amount of dye adsorbed (mg/g) by the adsorbent at equilibrium time
Ka - rate constant of adsorption in time-1
t - agitation time in minutes
Batch mode experiments were carried out by varying the concentration of the dye
solutions at 32 ± 2ºC and at pH 7.0 ± 0.2 for all the dyes used in this study. The data
obtained from Lagergren equation for the adsorption of the dyes from aqueous solution in
terms of variation of initial concentration of the dye solutions with the adsorbent BGA
80
are summarised in the Tables 27 - 30 and the corresponding Lagergren plots are shown in
Figures 29 - 32.
Attempts are made for the adsorption of the dyes used in this study from dyeing
industrial effluent onto BGA. The data obtained in this study are summarised in the
Tables 31 - 34 and the graphical representations are shown in Figures 33 - 36.
The linear plots obtained show the applicability of Lagergren rate equation for the
adsorption of the dyes used in this study and suggested the formation of monolayer of dyes
onto the surface of the adsorbent (Geetha et al., 2008). The rate constants Ka are
calculated from the slope of the plots of log (qe- q) vs t and are shown in Tables 27 - 34.
The values of correlation coefficient (r2) obtained, show good correlation. The rate
constant Ka decreases with increasing initial concentration of the dye solutions used in this
study. The reason for this behaviour can be attributed to the high competition for the
adsorption surface sites at high concentration which leads to lower adsorption rates
(Sen et al., 2011).
Similar types of kinetic model were reported for the adsorption of Rhodamine-B
using cocoa shell (Theivarasu et al., 2010) and for the removal of methylene blue onto
pine cone biomass (Sen et al., 2011).
81
Table 27
Lagergren Rate Equation for the Adsorption of Methylene Blue Dyefrom Aqueous Solution onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l 120mg/l
10 0.8235 1.0712 1.2098 1.5366
20 0.6128 1.0477 1.152 1.4632
30 0.5551 0.8338 0.9759 1.4397
40 0.4871 0.6794 0.7324 1.3458
50 0.3118 0.5705 0.6075 1.2813
60 0.1875 0.4914 0.6075 1.2058
90 0.1875 0.3945 0.5289 1.0874
120 0.0086 0.2695 0.1303 0.8382
150 -0.0292 -0.2076 -0.1739 0.1847
180 _ _ _ _
Intercept (log qe) 0.7089 1.0917 1.2315 1.6932
Slope (-Ka / 2.303) 0.00568 0.0082 0.0093 0.0085
Ka in min-1 x 10-22.2962 2.146 1.8885 1.3081
CorrelationCoefficient (r2) 0.9312 0.9677 0.9750 0.9582
82
Table 28
Lagergren Rate Equation for the Adsorption of Methyl Violet Dyefrom Aqueous Solution onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l 120mg/l
10 1.1179 1.4314 1.5315 1.5911
20 1.0414 1.3979 1.4624 1.5563
30 0.9542 1.2553 1.3802 1.5185
40 0.9031 1.2041 1.3010 1.4914
50 0.7782 1.0414 1.1761 1.3424
60 0.6021 0.9542 1.0792 1.2304
90 0.6021 0.8451 0.8451 1.1461
120 0.3010 0.6990 0.6990 0.9031
150 0.3010 0.3010 0.3010 0.4771
180 - - - -
Intercept (log qe) 1.1233 1.4918 1.6226 1.7314
Slope(-Ka / 2.303) 0.00616 0.00754 0.00847 0.00759
Ka in min-1x10-2 1.984 1.951 1.736 1.418
CorrelationCoefficient (r2) 0.9662 0.984 0.9947 0.9809
83
Table 29
Lagergren Rate Equation for the Adsorption of Acid Blue Dyefrom Aqueous Solution onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l 120mg/l
10 1.664 1.3679 1.4881 1.4449
20 1.1252 1.3359 1.4599 1.4103
30 1.0792 1.2632 1.3979 1.3724
40 0.9704 1.2219 1.3632 1.3310
50 0.9031 1.1761 1.2840 1.2343
60 0.8247 1.0671 1.1870 1.1092
90 0.6021 0.9207 1.0622 1.0302
120 0.4265 0.5224 0.7612 0.9330
150 0.1271 0.2227 0.2833 0.6325
180 _ _ _ _
Intercept (log qe) 1.4198 1.5290 1.6929 1.5182
Slope (-Ka / 2.303) 0.00887 0.00818 0.00847 0.00552
Ka in min-1 x10-22.279 1.951 1.884 1.772
CorrelationCoefficient (r2) 0.9493 0.9857 0.9773 0.9848
84
Table 30
Lagergren Rate Equation for the Adsorption of Acid Violet Dyefrom Aqueous Solution onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l 120mg/l
10 1.288 1.365 1.522 1.656
20 1.247 1.278 1.491 1.602
30 1.201 1.227 1.456 1.540
40 1.092 1.168 1.418 1.426
50 1.025 1.102 1.331 1.329
60 0.945 1.023 1.222 1.270
90 0.849 0.925 1.076 1.027
120 0.724 0.801 0.854 0.728
150 0.548 0.624 0.377 0.427
180 _ _ _ _
Intercept (log qe) 1.3214 1.3147 1.6848 1.7810
Slope (-Ka / 2.303) 0.00522 0.00502 0.00775 0.00881
Ka in min-1 x10-22.0299 1.7844 1.2014 1.1553
CorrelationCoefficient (r2) 0.9908 0.9939 0.9774 0.9982
85
Figure 29
Figure 30
0.0
0.4
0.8
1.2
1.6
2.0
0 20 40
log
(qe
-q)
Lagergren Rate Equation for the Adsorption of Methyl VioletDye from Aqueous Solution onto BGA
60mg/l 80mg/l
85
Figure 29
Figure 30
40 60 80 100 120 140 160Time in minutes
Lagergren Rate Equation for the Adsorption of Methyl VioletDye from Aqueous Solution onto BGA
80mg/l 100mg/l 120mg/l
85
Figure 29
Figure 30
160
86
Figure 31
Figure 32
87
Table 31
Lagergren Rate Equation for the Adsorption of Methylene Blue Dye fromDyeing Industrial Effluent onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l
10 0.9206 1.0849 0.9936
20 0.8235 1.0615 0.9619
30 0.7860 1.0366 0.9267
40 0.6990 1.0103 0.8476
50 0.6474 0.9823 0.8021
60 0.5224 0.8476 0.6929
90 0.3464 0.7604 0.5465
120 0.2201 0.2833 0.4502
150 0.2596 0.1072 0.1492
180 _ _ _
Intercept (log qe) 0.9094 1.2626 1.7856
Slope (-Ka / 2.303) 0.00519 0.00735 0.00585
Ka in min-1 x10-2 1.693 1.347 1.195
CorrelationCoefficient (r2) 0.9600 0.9698 0.9913
88
Table 32
Lagergren Rate Equation for the Adsorption of Methyl Violet Dye fromDyeing Industrial Effluent onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l
10 1.291 1.416 1.424
20 1.259 1.386 1.351
30 1.224 1.354 1.309
40 1.186 1.319 1.264
50 0.9899 1.085 1.213
60 0.9232 1.018 1.088
90 0.8439 0.939 0.788
120 0.4456 0.718 0.611
150 0.1461 0.542 0.309
180 _ _ _
Intercept (log qe) 1.4430 1.4968 1.5499
Slope (-Ka / 2.303) 0.008208 0.00648 0.008056
Ka in min-1 x10-2 1.49 1.86 1.89
CorrelationCoefficient (r2) 0.9848 0.9828 0.9946
89
Table 33
Lagergren Rate Equation for the Adsorption of Acid Blue Dye fromDyeing Industrial Effluent onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l
10 1.3655 1.3159 1.3729
20 1.3159 1.2742 1.3304
30 1.2672 1.2355 1.2553
40 1.2175 1.1847 1.1931
50 1.1553 1.1173 1.0864
60 1.0828 1.0212 0.9395
90 0.9345 0.9085 0.7993
120 0.7709 0.6989 0.6812
150 0.4472 0.4472 0.4914
180 _ _ _
Intercept (log qe) 1.4565 1.4094 1.4236
Slope (-Ka / 2.303) 0.00623 0.00611 0.00643
Ka in min-1 x10-2 1.479 1.4345 1.407
CorrelationCoefficient (r2) 0.9914 0.9946 0.9889
90
Table 34
Lagergren Rate Equation for the Adsorption of Acid Violet Dye fromDyeing Industrial Effluent onto BGA
Time inminutes
log (qe – q )
60mg/l 80mg/l 100mg/l
10 1.243 1.253 1.317
20 1.176 1.237 1.276
30 1.138 1.149 1.229
40 1.051 1.041 1.179
50 1.000 0.895 1.121
60 0.796 0.798 1.121
90 0.699 0.673 0.975
120 0.374 0.469 0.878
150 0.398 0.196 0.578
180 _ _ _
Intercept (log qe) 1.4072 1.3574 1.3215
Slope (-Ka / 2.303) 0.0061 0.00762 0.0079
Ka in min-1 x10-2 3.43 3.31 2.64
CorrelationCoefficient (r2) 0.9984 0.9986 0.9977
91
Figure 33
Figure 34
92
Figure 35
Figure 36
0.3
0.7
1.1
1.5
0 50 100 150 200
log
(qe
-q)
Time in minutes
Lagergren Rate Equation for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
60mg/l 80mg/l 100mg/l
0.0
0.4
0.8
1.2
1.6
0 20 40 60 80 100 120 140 160 180
log
(qe
-q)
Time in minutes
Lagergren Rate Equation for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
60mg/l 80mg/l 100mg/l
93
4.8.2 Intraparticle Diffusion Rate Equation
There is a possibility of transport of dye molecules from the bulk into pores of the
adsorbent as well as, adsorption at the outer surface of the adsorbent. The rate limiting
step in the adsorption may be either film diffusion or intraparticle diffusion. As they act in
series, the slower of the two will be the rate determining step. The possibility of the dye
species to diffuse into the interior sites of the particles of adsorbent was tested with Weber-
Morris equation given as follows (Weber and Morris, 1963; Lalitha et al., 2011):
q = Kpt1/2
where,
‘q’ is the amount of dye adsorbed (mg/g) by the adsorbent at time ‘t’Kp is the intraparticle diffusion rate constant and
‘t’ is the time (agitation time) in minutes
In order to study the diffusion process, batch mode experiments are carried out with
the adsorbent BGA at 32 ± 2ºC and at pH 7.0 ± 0.2 by varying the initial concentration of
the aqueous dye solutions used in this study. The results are given in the Tables 35 – 38
and graphically shown in Figures 37 - 40.
Adsorption of the dyes (Methylene Blue, Methyl Violet, Acid Blue and Acid Violet)
from dyeing industrial effluent onto BGA is also carried out at 32 ± 2ºC and at pH 7.0 ± 0.2
by varying the concentration of the dye. The data obtained are summarised in the Tables
39 – 42 and the graphical representations are shown in Figures 41 - 44.
The rate constant for intraparticle diffusion Kp for various initial concentrations of the
dyes are determined from the slope of the linear equation drawn between square root of
time (t1/2) and the amount of adsorbate adsorbed (q). Values of Kp increased with increase
in initial dye concentration which shows that the adsorption rate is governed by the diffusion
of the dye within the pores of the adsorbent (Vucurovic et al., 2012).
If the intraparticle diffusion is the rate controlling step, the plot should be linear and
pass through the origin. It can be noticed from the Figures 37– 44, the plots are linear but
not passing through the origin and this deviation from the origin or near saturation might be
due to the difference in mass transfer rate in the initial and final stages of adsorption
(Theydan et al., 2012). It also indicates that there is an initial boundary layer resistance
and intraparticle diffusion is not the sole rate controlling step, but other kinetic models may
simultaneously control the adsorption rate (Ma et al., 2012).
94
Similar results were reported in the literature for the adsorption of crystal violet onto
Opal (Ma et al., 2012), adsorption of methylene blue onto sugar extracted spent rice
biomass (Rehman et al., 2012), on sugar beet pulp (Vucrovic et al., 2012), on rice husk
(Safa and Bhatti, 2011) and on teak tree bark powder (Satish Patil et al., 2011).
Table 35
Intraparticle Diffusion Rate Equation for the Adsorption of Methylene BlueDye from Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial Concentration of Methylene Blue Dyein mg/l
Amount of dye adsorbed (q) in mg
60mg 80mg 100mg 120mg
10 3.1623 50.3 62.4 75.7 79.6
20 4.4721 52.8 63.3 77.7 78.3
30 5.4772 53.3 67.6 82.4 83.8
40 6.3246 53.9 69.5 86.5 87.1
50 7.0711 54.4 70.7 87.2 89.2
60 7.7460 54.9 71.3 87.8 90.3
90 9.4868 55.4 71.9 88.5 92.1
120 10.9545 55.9 72.6 90.5 93.4
150 12.2474 56.4 73.8 91.2 94.8
180 13.4164 56.9 74.4 92.6 96.3
Intercept 49.89 56.16 72.85 50.99
Slope (Kp) x10-3 0.543 1.596 1.683 3.569
Correlation Coefficient (r2) 0.918 0.869 0.912 0.996
95
Table 36
Intraparticle Diffusion Rate Equation for the Adsorption of Methyl VioletDye from Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial Concentration of the Methyl Violet Dyein mg/l
Amount of dye adsorbed (q) in mg60mg 80mg 100mg 120mg
10 3.1623 35.63 36.57 43.90 45.32
20 4.4721 37.60 38.86 48.78 50.23
30 5.4772 39.68 45.71 53.66 55.81
40 6.3246 41.25 48.00 58.54 58.60
50 7.0711 43.13 52.57 63.41 66.98
60 7.7460 44.68 54.86 65.87 72.56
90 9.4868 45.23 57.14 70.73 75.35
120 10.9545 46.88 59.43 73.17 80.93
150 12.2474 47.08 61.71 75.61 86.51
180 13.4164 48.75 64.00 78.05 89.30
Intercept 33.7865 29.3078 34.681 34.901
Slope ( Kp) x10-3 1.1779 2.8544 3.608 4.1997
Correlation Coefficient (r2) 0.9387 0.9644 0.9761 0.9828
96
Table 37
Intraparticle Diffusion Rate Equation for the Adsorption of Acid BlueDye from Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage: 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial Concentration of Acid Blue Dyein mg/l
Amount of dye adsorbed (q) in mg
60mg 80mg 100mg 120mg
10 3.1623 32.00 36.67 38.46 45.00
20 4.4721 33.33 38.33 40.39 47.14
30 5.4772 34.67 41.67 44.23 49.29
40 6.3246 37.33 43.33 46.15 51.43
50 7.0711 38.67 45.00 50.00 55.71
60 7.7460 40.00 48.33 53.85 60.00
90 9.4868 42.67 51.67 57.69 62.14
120 10.9545 44.00 56.67 63.46 64.29
150 12.2474 45.33 58.33 67.31 68.57
180 13.4164 46.67 60.00 69.23 72.86
Intercept 27.43 28.32 27.06 35.59
Slope (Kp) x 10-3 1.4976 2.547 2.786 3.434
Correlation Coefficient (r2) 0.9892 0.9947 0.9952 0.9834
97
Table 38
Intraparticle Diffusion Rate Equation for the Adsorption of Acid VioletDye from Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage: 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial concentration of Acid Violet Dyein mg/l
Amount of dye adsorbed (q) in mg
60mg 80mg 100mg 120mg
10 3.1623 17.7 27.4 35.72 45.3
20 4.4721 19.4 31.6 38.10 50.7
30 5.4772 21.2 33.7 40.48 56.0
40 6.3246 24.7 35.8 42.86 64.0
50 7.0711 26.5 37.9 47.62 69.3
60 7.7460 28.2 40.0 52.38 72.0
90 9.4868 30.0 42.1 57.14 80.0
120 10.9545 31.8 44.2 61.91 85.3
150 12.2474 33.5 46.3 66.67 88.0
180 13.4164 37.1 50.5 69.05 90.7
Intercept 12.24 22.56 22.83 33.02
Slope (Kp) x 10-3 1.84 2.07 3.53 4.62
Correlation Coefficient(r2) 0.9863 0.9864 0.9929 0.9824
98
Figure 37
Figure 38
20
40
60
80
100
2 4 6 8 10 12 14
Amou
nt o
f dye
ads
orbe
d (q
) in
mg
√ t
Intraparticle Diffusion Rate Equation for the Adsorption ofMethylene Blue Dye from Aqueous Solution onto BGA
60mg 80mg 100mg 120 mg
10
30
50
70
90
2 4 6 8 10 12 14Amou
nt o
f dye
ads
orbe
d (q
) in
mg
√ t
Intraparticle Diffusion Rate Equation for the Adsorption ofMethyl Violet Dye from Aqueous Solution onto BGA
60mg 80mg 100mg 120 mg
99
Figure 39
Figure 40
10
30
50
70
90
2 4 6 8 10 12 14Amou
nt o
f dye
ads
orbe
d (q
) in
mg
√ t
Intraparticle Diffusion Rate Equation for the Adsorption ofAcid Blue Dye from Aqueous Solution onto BGA
60mg 80mg 100mg 120 mg
10
30
50
70
90
3 5 7 9 11 13 15
Amou
nt o
f dye
ads
orbe
d (q
) in
mg
√ t
Intraparticle Diffusion Rate Equation for the Adsorption ofAcid Violet Dye from Aqueous Solution onto BGA
60mg 80mg 100mg 120 mg
100
ble 39
Intraparticle Diffusion Rate Equation for the Adsorption of Methylene BlueDye from Dyeing Industrial Effluent onto BGA
Conditions:
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial Concentration of Methylene Blue Dye inmg/l
Amount of dye adsorbed (q) in mg
60mg 80mg 100mg
10 3.1623 26.11 31.36 35.21
20 4.4721 27.78 32.00 35.91
30 5.4772 28.33 32.64 36.62
40 6.3246 29.44 33.28 38.03
50 7.0711 30.00 33.92 38.73
60 7.7460 31.11 36.48 40.14
90 9.4868 32.22 37.76 41.55
120 10.9545 32.78 41.60 42.25
150 12.2474 33.89 42.24 43.66
180 13.4164 34.44 43.54 45.07
Intercept 23.94 25.84 31.83
Slope Kp x 10-3 0.7999 0.9798 1.3254
Correlation Coefficient (r2) 0.9892 0.9745 0.9905
101
Table 40
Intraparticle Diffusion Rate Equation for the Adsorption of Methyl Violet Dyefrom Dyeing Industrial Effluent onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial Concentration of Methyl Violet Dye in mg/lAmount of dye adsorbed (q) in mg
60mg 80mg 100mg
10 3.1623 26.51 34.78 42.86
20 4.4721 27.91 36.52 46.93
30 5.4772 29.30 38.26 48.98
40 6.3246 30.70 40.00 51.02
50 7.0711 36.28 48.70 53.06
60 7.7460 37.67 50.44 57.14
90 9.4868 39.07 52.17 63.26
120 10.9545 43.26 55.65 65.31
150 12.2474 44.65 57.39 67.35
180 13.4164 46.05 60.87 69.39
Intercept 19.4377 25.9155 34.7236
Slope Kp x 10-3 2.0785 2.6833 2.7136
Correlation Coefficient (r2) 0.9798 0.9693 0.9731
102
Table 41
Intraparticle Diffusion Rate Equation for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial Concentration of Acid Blue Dye in mg/lAmount of dye adsorbed (q) in mg
60mg 80mg 100mg
10 3.1623 28.6 35.3 38.5
20 4.4721 30.8 37.2 41.0
30 5.4772 34.2 38.8 43.2
40 6.3246 36.6 40.7 45.2
50 7.0711 40.0 42.9 47.4
60 7.7460 43.5 45.5 49.6
90 9.4868 4 5.9 47.9 53.1
120 10.9545 47.4 51.0 55.8
150 12.2474 49.1 53.2 58.9
180 13.4164 52.2 56.0 61.7
Intercept 22.168 28.230 31.078
Slope Kp x 10-3 2.0681 2.2850 2.3224
Correlation Coefficient (r2) 0.9792 0.9966 0.9988
103
Table 42
Intraparticle Diffusion Rate Equation for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes √t
Initial Concentration of Acid Violet Dye in mg/l
Amount of dye adsorbed (q) in mg
60mg 80mg 100mg
10 3.1623 23.75 32.31 39.62
20 4.4721 26.25 32.94 41.51
30 5.4772 27.50 36.08 43.40
40 6.3246 30.00 39.22 45.28
50 7.0711 31.25 42.35 47.17
60 7.7460 35.00 43.92 47.17
90 9.4868 36.25 45.49 50.94
120 10.9545 37.50 47.06 52.83
150 12.2474 38.75 48.63 56.60
180 13.4164 41.25 50.20 60.38
Intercept 19.1911 27.1441 32.8714
Slope Kp x 10-3 1.6873 1.8263 1.9436
Correlation Coefficient (r2) 0.9805 0.9678 0.9934
104
Figure 41
Figure 42
20
25
30
35
40
45
50
3 5 7 9 11 13Amou
nt o
f dye
ads
orbe
d(q)
in m
g
√ t
Intraparticle Diffusion Rate Equation for the adsorption ofMethylene Blue Dye from Dyeing Industrial Effluent onto BGA
60mg 80mg 100mg
25
35
45
55
65
3 5 7 9 11 13Amou
nt o
f dye
ads
orbe
d(q)
in m
g
√ t
Intraparticle Diffusion Rate Equation for the Adsorption ofMethyl Violet Dye from Dyeing Industrial Effluent onto BGA
60mg 80mg 100mg
105
Figure 43
Figure 44
20
30
40
50
60
70
3 5 7 9 11 13Amou
nt o
f dye
ads
orbe
d(q)
in m
g
√ t
Intraparticle Diffusion Rate Equation for the Adsorption ofAcid Blue Dye from Dyeing Industrial Effluent onto BGA
60mg 80mg 100mg
20
30
40
50
60
70
3 5 7 9 11 13Amou
nt o
f dye
ads
orbe
d(q)
in m
g
√ t
Intraparticle Diffusion Rate Equation for the Adsorption ofAcid Violet Dye from Dyeing Industrial Effluent onto BGA
60mg 80mg 100mg
106
4.8.3 Elovich Rate Equation
The Elovich equation was developed to describe the kinetics of chemisorption of
gases onto solids and it is generally expressed as:
dqt/dt = α exp (-βqt)where,
‘qt’ is the amount of dye adsorbed (mg/g) by the adsorbent at time ‘t’
‘α’ is the initial adsorption rate (mg g-1 min-1) and
‘β’ is the desorption constant (g mg-1 ) during any experiment.
Assuming the initial boundary condition, q = 0 at t=0, the above equation on
integration become,
1/qt = 1/β ln (1+ αβt)
To simplify the Elovich’s equation, Chien and Clayton (1980) assumed αβ >> 1 and
applying the boundary conditions qt = 0 at t= 0 and qt = qt at t = t, equation becomes
(Zeldowitsch, 1934; Satish Patil et al., 2011)
qt = 1/β ln (αβ) +1/β ln t
This equation is commonly used for the chemisorptions and this model can be
applied with success in liquid solution (Gulmardes Gusmao et al., 2012). Elovich plots of
ln t vs q (amount of dye adsorbed (mg/g) by the adsorbent at time‘t’) gives a linear
relationship with a slope of 1/β and an intercept of 1/β ln (αβ). The Elovich rate equation
data obtained in this study for the adsorption of MB, MV, AB and AV from aqueous solution
onto BGA are summarised in Tables 43 - 46 and graphically shown in Figure 45 - 48. The
high correlation coefficient (r2) shows the successfulness of the Elovich model.
Attempts are made for the adsorption of the dyes used in this study from dyeing
industrial effluent onto BGA. The Elovich rate equation data obtained in this study are
summarised in the Tables 47 – 50 and the graphical representations are shown in Figures
49 - 52.
The higher value of initial adsorption rate (α) may be due to the greater surface area
of the adsorbent BGA, for the immediate adsorption of dyes from aqueous solution and
also from dyeing industrial effluent (Satish Patil et al., 2011). The value of desorption
constant (β) decreases with the increase of the initial concentration of the dye solutions.
107
The results obtained in this study are similar with the results reported for the
adsorption of methylene blue using teak tree bark powder by Satish Patil et al., (2011) and
the adsorption of methylene blue and genetian violet onto succinylated sugar cane bagasse
by Gulmardes Gusmao et al., (2012).
Table 43
Elovich Rate Equation for the Adsorption of Methylene Blue Dyefrom Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚ C
Timein minutes ln t
Initial Concentration of the Dye in mg/lAmount of dye adsorbed (q) in mg
60mg 80mg 100mg 120mg10 2.3030 50.3 62.6 75.7 79.6
20 2.9960 52.8 63.3 77.7 78.3
30 3.4012 53.3 67.6 82.4 83.8
40 3.6889 53.9 69.5 86.5 87.1
50 3.9120 54.4 70.7 87.2 89.2
60 4.0943 54.9 71.3 87.8 90.3
90 4.4998 55.4 71.9 88.5 92.1
120 4.7875 55.9 72.6 90.5 93.4
150 5.0106 56.4 73.8 91.2 94.8
180 5.1930 56.9 74.4 92.6 96.3
Intercept (1/β) x ln αβ 45.99 44.91 61.76 29.47
Slope (1/β) 2.140 6.019 6.123 12.522
Desorption Constant (β) 0.4673 0.1661 0.1633 0.0799Initial adsorption rateconstant (α) x102 2.715 1.549 1.471 0.348
Correlation Coefficient (r2) 0.9736 0.9474 0.9618 0.9835
108
Table 44
Elovich Rate Equation for the Adsorption of Methyl Violet Dyefrom Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes ln t
Initial Concentration of the Dye in mg/lAmount of dye adsorbed (q) in mg
60mg 80mg 100mg 120mg10 2.3030 35.63 36.57 43.90 45.36
20 2.996 37.60 38.86 48.78 50.23
30 3.4012 39.68 45.71 53.66 55.81
40 3.6889 41.25 48.00 58.54 58.60
50 3.9120 43.13 52.57 63.41 66.98
60 4.0943 44.68 54.86 65.87 72.56
90 4.4998 45.23 57.14 70.73 75.35
120 4.7875 46.88 59.43 73.17 80.93
150 5.0106 47.08 61.71 75.61 86.51
180 5.1930 48.75 64.00 78.05 89.30
Intercept (1/β) x ln αβ 24.57 25.72 12.81 9.66
Slope (1/β) 0.46 0.434 1.263 1.486
Desorption Constant(β) 0.2090 0.0995 0.0792 0.0657
Initial adsorption rateconstant (α) x102 6.074 3.2477 3.4834 2.5646
Correlation Coefficient (r2) 0.9806 0.9752 0.9912 0.9681
109
Table 45
Elovich Rate Equation for the Adsorption of Acid Blue Dyefrom Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes ln t
Initial Concentration of the Dye in mg/lAmount of dye adsorbed (q) in mg
60mg 80mg 100mg 120mg
10 2.3030 32.00 36.67 38.46 45.00
20 2.996 33.33 38.33 40.39 47.14
30 3.4012 34.67 41.67 44.23 49.29
40 3.6889 37.33 43.33 46.15 51.43
50 3.9120 38.67 45.00 50.00 55.71
60 4.0943 40.00 48.33 53.85 60.00
90 4.4998 42.67 51.67 57.69 62.14
120 4.7875 44.00 56.67 63.46 64.29
150 5.0106 45.33 58.33 67.31 68.57
180 5.1930 46.67 60.00 69.23 72.86
Intercept (1/β)x ln αβ 17.54 12.70 11.66 18.13
Slope (1/β) 5.497 8.848 8.126 9.906
Desorption Constant (β) 0.1819 0.1169 0.1231 0.1010
Initial adsorption rateconstant (α) x102 2.272 1.751 1.478 2.193
Correlation Coefficient (r2) 0.9850 0.9748 0.9724 0.9682
110
Table 46
Elovich Rate Equation for the Adsorption of Acid Violet Dyefrom Aqueous Solution onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes ln t
Initial Concentration of the Dye in mg/lAmount of dye adsorbed (q) in mg
60mg 80mg 100mg 120mg
10 2.3030 17.7 27.4 35.72 45.3
20 2.996 19.4 31.6 38.10 48.7
30 3.4012 21.2 33.7 40.48 51.0
40 3.6889 24.7 35.8 42.86 56.0
50 3.9120 26.5 37.9 47.62 59.3
60 4.0943 28.2 40.0 52.38 62.0
90 4.4998 30.0 42.1 57.14 68.0
120 4.7875 31.8 44.2 61.91 75.3
150 5.0106 33.5 46.3 66.67 78.0
180 5.1930 37.1 50.5 69.05 80.7
Intercept (1/β)x ln αβ 1.5664 8.6046 0.6691 1.6694
Slope (1/β) 6.7375 7.6077 12.6668 17.1647
Desorption Constant (β) 0.1484 0.1315 0.0789 0.0583
Initial adsorption rateconstant (α) x102 0.8501 2.3575 1.3355 1.8918
Correlation Coefficient(r2) 0.9841 0.9884 0.9591 0.9904
111
Figure 45
Figure 46
40
60
80
100
2 2.5 3Amou
nt o
f dye
ads
orbe
d (q
) in
mg
Elovich Rate Equation for the Adsorption of Methylene BlueDye from Aqueous Solution onto BGA
60mg
30
50
70
90
2 2.5 3Amou
nt o
f dye
ads
orbe
d (q
) in
mg
Elovich Rate Equation for the Adsorption of Methyl VioletDye from Aqueous Solution onto BGA
60mg
111
Figure 45
Figure 46
3 3.5 4 4.5 5 5.5ln t
Elovich Rate Equation for the Adsorption of Methylene BlueDye from Aqueous Solution onto BGA
80mg 100mg 120 mg
3 3.5 4 4.5 5 5.5ln t
Elovich Rate Equation for the Adsorption of Methyl VioletDye from Aqueous Solution onto BGA
80mg 100mg 120 mg
111
Figure 45
Figure 46
5.5
Elovich Rate Equation for the Adsorption of Methylene BlueDye from Aqueous Solution onto BGA
5.5
112
Figure 47
Figure 48
30
40
50
60
70
80
2 2.5 3 3.5 4 4.5 5 5.5Amou
nt o
f dye
ads
orbe
d (q
) in
mg
ln t
Elovich Rate Equation for the Adsorption of Acid Blue Dyefrom Aqueous Solution onto BGA
60mg 80mg 100mg 120 mg
30
40
50
60
70
80
2 2.5 3 3.5 4 4.5 5 5.5Amou
nt o
f dye
ads
orbe
d (q
) in
mg
ln t
Elovich Rate Equation for the Adsorption of Acid Violet Dyefrom Aqueous Solution onto BGA
60mg 80mg 100mg 120 mg
113
Table 47
Elovich Rate Equation for the Adsorption of Methylene Blue Dyefrom Dyeing Industrial Effluent onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes ln t
Initial Concentration of the Dye in mg/l
Amount of dye adsorbed (q) in mg
60mg 80mg 100mg
10 2.3030 26.11 31.36 35.21
20 2.9960 27.78 32.00 35.91
30 3.4012 28.33 32.64 36.62
40 3.6889 29.44 33.28 38.03
50 3.9120 30.00 33.92 38.73
60 4.0943 31.11 36.48 40.14
90 4.4998 32.22 37.76 41.55
120 4.7875 32.78 41.60 42.25
150 5.0106 33.89 42.24 43.66
180 5.1930 34.44 43.54 45.07
Intercept (1/β)x ln αβ 19.00 19.05 26.34
Slope (1/β) 2.90 4.32 3.32
Desorption Constant (β) 0.3448 0.3016 0.2315
Initial adsorption constantrate (α) x102 4.988 2.931 1.044
Correlation Coefficient (r2) 0.9914 0.9908 0.9719
114
Table 48
Elovich Rate Equation for the Adsorption of Methyl Violet Dyefrom Dyeing Industrial Effluent onto BGA
Conditions :
Adsorbent Dosage : 500mgpH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes ln t
Initial Concentration of the Dye in mg/l
Amount of dye adsorbed (q) in mg
60mg 80mg 100mg
10 2.3030 26.51 34.78 42.86
20 2.996 27.91 36.52 46.93
30 3.4012 29.30 38.26 48.98
40 3.6889 30.70 40.00 51.02
50 3.9120 36.28 48.70 53.06
60 4.0943 37.67 50.44 57.14
90 4.4998 39.07 52.17 63.26
120 4.7875 43.26 55.65 65.31
150 5.0106 44.65 57.39 67.35
180 5.1930 46.05 60.87 69.39
Intercept (1/β)x ln αβ 5.9801 8.3131 17.0290
Slope (1/β) 7.5615 9.8191 9.9034
Desorption Constant (β) 0.1323 0.1018 0.1010
Initial adsorption constantrate (α) x102 0.7653 0.7924 0.7933
Correlation Coefficient (r2) 0.9671 0.9623 0.9799
115
Table 49
Elovich Rate Equation for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes ln t
Initial Concentration of the Dye in mg/l
Amount of dye adsorbed (q) in mg60mg 80mg 100mg
10 2.3030 28.6 35.3 38.5
20 2.996 30.8 37.2 41.0
30 3.4012 34.2 38.8 43.2
40 3.6889 36.6 40.7 45.2
50 3.9120 40.0 42.9 47.4
60 4.0943 43.5 45.5 49.6
90 4.4998 45.9 47.9 53.1
120 4.7875 47.4 51.0 55.8
150 5.0106 49.1 53.2 58.9
180 5.1930 52.2 56.0 61.7
Intercept (1/β)x ln αβ 6.4877 15.1464 16.5282
Slope (1/β) 8.6101 7.4471 8.2514
Desorption Constant (β) 0.1461 0.1342 0.1212
Initial adsorption constantrate (α) x102
0.7047 0.3631 0.3871
Correlation Coefficient (r2) 0.9849 0.9736 0.9785
116
Table 50
Elovich Rate Equation for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
Conditions :
Adsorbent Dosage : 500mg
pH : 7.0 ± 0.2
Temperature : 32 ± 2˚C
Timein minutes
ln tInitial Concentration of the Dye in mg/l
Amount of dye adsorbed (q) in mg60mg 80mg 100mg
10 2.3030 23.75 32.31 39.62
20 2.996 26.25 32.94 41.51
30 3.4012 27.50 36.08 43.40
40 3.6889 30.00 39.22 45.28
50 3.9120 31.25 42.35 47.17
60 4.0943 35.00 43.92 47.17
90 4.4998 36.25 45.49 50.94
120 4.7875 37.50 47.06 52.83
150 5.0106 38.75 48.63 56.60
180 5.1930 41.25 50.20 60.38
Intercept (1/β)x ln αβ 8.617 14.765 23.504
Slope (1/β) 6.016 6.777 6.139
Desorption constant (β) 0.1662 0.1476 0.1329
Initial adsorption constantrate (α) x102 0.2520 0.5987 2.8239
Correlation Coefficient (r2) 0.9798 0.9744 0.9716
117
Figure 49
Figure 50
25.0
30.0
35.0
40.0
45.0
50.0
2 2.5 3 3.5 4 4.5 5 5.5
Amou
nt o
f dye
ads
orbe
d (q
)in m
g
ln t
Elovich Rate Equation for the Adsorption of Methylene BlueDye from Dyeing Industrial Effluent onto BGA
60mg 80mg 100mg
20
30
40
50
60
70
2 2.5 3 3.5 4 4.5 5 5.5Am
ount
of d
ye a
dsor
bed
(q) i
n m
g
ln t
Elovich Rate Equation for the Adsorption of Methyl Violet Dyefrom Dyeing Industrial Effluent onto BGA
60mg 80mg 100mg
118
Figure 51
Figure 52
25
35
45
55
65
2 2.5 3 3.5 4 4.5 5 5.5Amou
nt o
f dye
ads
orbe
d (q
) in
mg
ln t
Elovich Rate Equation for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
60mg 80mg 100mg
2025303540455055606570
2 2.5 3 3.5 4 4.5 5 5.5Amou
nt o
f dye
ads
orbe
d (q
) in
mg
ln t
Elovich Rate Equation for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
60mg 80mg 100mgLinear (60mg) Linear (80mg) Linear (100mg)
119
4.9 Adsorption Isotherms
The application of adsorption isotherm is very useful to describe the interaction
between the adsorbate and the adsorbent of any system. The parameters obtained from
the adsorption isotherms provide important information on the adsorption mechanism, the
surface properties and affinities of the adsorbent (Vargas et al., 2011). The equilibrium
isotherm value is of fundamental importance for the design and optimisation of the
adsorption system for the removal of the dyes from aqueous solution. Therefore, it is
necessary to establish the most appropriate correlation for the equilibrium curves
(Saeed et al., 2010).
In the present study, the most commonly used isotherm models, namely, the
Langmuir and Freundlich adsorption isotherms, are used to describe the adsorption
equilibrium. Adsorption isotherms are studied by varying the initial concentration of the dye
solution (Methylene Blue, Methyl Violet, Acid Blue and Acid Violet) using the adsorbent
Blue-Green Algae (BGA).
4.9.1 Langmuir Adsorption Isotherm
Langmuir adsorption isotherm was developed by Irvin Langmuir, describe the
surface coverage of adsorbate on a solid surface. Langmuir adsorption isotherm is based
on the assumption that points of valency exist on the surface of the adsorbent and that
each of these sites is capable of adsorbing only one molecule. Thus, the adsorbed layer
will be one molecule thickness. Further, it is assumed that all the adsorption sites have
equal affinities for the adsorbate and the presence of adsorbed molecules at one site will
not affect the adsorption of molecules at an adjacent site (Renugadevi et al., 2009a). The
intermolecular forces decrease rapidly with distance, and consequently the existence of
monolayer coverage of the adsorbate at the outer surface can be predicted
(Saeed et al., 2010). The Langmuir adsorption isotherm is generally expressed as
(Langmuir, 1916; Renugadevi et al., 2009a)
k1 Cex/m =
1 + k11Ce
where,
x is the amount of the dye adsorbed (mg/l),
m is the amount of adsorbent (mg),
Ce is the equilibrium concentration of dye adsorbed on BGA and
120
k1 is a Langmuir constant corresponding to the measure of maximum energy of
adsorption capacity.
On rearranging, the above equation becomes,
m/x = 1/ (k1/ k11) + 1/ k1Ce
The linear plot of 1/Ce versus m/x (Figure 53 - 60) obtained in this study shows
the applicability of Langmuir adsorption isotherm indicating the formation of monolayer
coverage of adsorbate on the surface of the adsorbent Blue-Green Algae. The Langmuir
adsorption isotherm data obtained for the removal of dyes from aqueous solution and from
dyeing industrial effluents onto BGA are summarised in the Tables 51 - 58 and the
graphical representations are shown in Figures 53 - 60.
Separation Factor (RL): The effect of isotherm has been taken into consideration
with a view to predict whether the studied adsorption system is favourable or unfavourable.
The essential characteristics of Langmuir isotherm can be expressed in terms of a
dimensionless constant, separation factor or equilibrium parameter ‘RL’ which is defined as
RL = 1 / 1+ bC0where,
C0 is the initial concentration of the dye solution and
b is the Langmuir constant.
The value of RL and the feasibility of the adsorption process are as follows
(Unuabonah et al., 2009):
RL value Type of isotherm
RL > 1
RL = 1
RL < 1
RL = 0
Unfavourable
Linear
Favourable
Irreversible
In this study, RL values obtained are found to be less than one, confirming the
favourable uptake of the dyes onto BGA adsorbent. The Langmuir model shows the best fit
with the highest correlation coefficient (r2) values in the range of 0.9759 - 0.9971, indicates
the feasibility of the adsorption of the dyes from aqueous solution and from dyeing
industrial effluents using the adsorbent Blue-Green Algae, also suggest the monolayer
121
coverage of the dyes onto BGA (Yi Liu et al., 2010) and the homogeneous distribution of
active sites on the surface of the adsorbent BGA.
Similar results have been reported in the adsorption of methylene blue on defatted
carica papaya seeds (Unuabonah et al., 2009), vermiculite hydrogel composites
(Yi Liu et al., 2010), and annona squmosa seed activated carbon (Santhi et al., 2010).
122
Table 51
Langmuir Isotherm for the Adsorption of Methylene Blue Dyefrom Aqueous Solution onto BGA
Timein
minutes
InitialConcentration
in mg/l1/Ce m/x Separation
Factor RL
Interceptk1
1 / k1
Slope1/ k1
1
CorrelationCoefficient
r2
10
6080
100120
0.10270.05760.04110.0172
9.9488.0767.9826.607
0.04810.03650.02940.0246
6.62 30.43 0.7379
20
6080
100120
0.13930.05970.04480.0189
9.4667.9047.4346.435
0.03820.02890.02330.0195
6.45 24.08 0.8528
30
6080
100120
0.14990.08070.05690.0195
9.3767.3976.0667.269
0.03820.02890.02330.0196
6.34 23.93 0.7909
40
6080
100120
0.16260.09490.07400.0218
9.2857.1985.7816.744
0.03880.02940.02360.0198
5.47 24.21 0.7949
50
6080
100120
0.17900.10750.07800.0234
9.1917.0725.7346.477
0.03290.02480.02000.0167
5.47 20.34 0.8869
60
6080
100120
0.21650.11520.08220.0252
9.1127.0116.2316.066
0.03360.02540.02040.0171
5.34 20.68 0.9381
90
6080
100120
0.21650.12410.08700.0279
9.0296.9505.9495.647
0.03230.02440.01960.0164
4.86 19.90 0.9227
120
6080
100120
0.24390.13440.10570.0327
8.9456.8915.5925.522
0.04310.03270.02630.0220
4.53 27.39 0.9339
150
6080
100120
0.27860.13440.11390.0397
8.8646.7755.4815.275
0.03450.02590.02080.0174
4.26 21.17 0.9601
180
6080
100120
0.32460.17920.12330.0422
8.7846.7195.4415.192
0.03160.02390.01920.0161
4.58 19.60 0.9759
123
Langmuir Isotherm for the Adsorption of Methylene Blue Dyefrom Aqueous Solution onto BGA
Figure 53
124
Table 52
Langmuir Isotherm for the Adsorption of Methyl Violet Dyefrom Aqueous Solution onto BGA
Timein
minutes
InitialConcentration
in mg/l1/Ce m/x
SeparationFactor
RL
Interceptk1/ k1
1Slope1/ k1
1CorrelationCoefficient
r2
10
6080100120
0.04100.02300.01780.0143
14.03313.67211.38909.954
0.09980.08480.06980.0545
9.05 13.37 0.8207
20
6080100120
0.04440.02430.01780.0143
13.30012.87010.25009.430
0.11000.09340.07670.0600
8.44 11.99 0.8444
30
6080100120
0.04840.02910.02150.0155
12.69010.93009.32008.960
0.11220.09520.07810.0611
7.11 11.74 0.9843
40
6080100120
0.05330.03130.02410.0163
12.12010.42008.54008.530
0.12530.10610.08690.0677
6.65 10.41 0.9609
50
6080100120
0.05920.03620.02780.0189
11.59009.51007.89007.470
0.12250.10370.08500.0663
5.33 10.66 0.9862
60
6080100120
0.06670.03980.02930.0211
11.11009.11007.59006.890
0.13870.11720.09580.0743
5.02 9.33 0.9906
90
6080100120
0.06670.04370.03420.0234
11.11008.75007.07006.340
0.11530.09770.08020.0627
3.53 11.40 0.9923
120
6080100120
0.07620.04860.03730.0256
10.67008.41006.83006.180
0.14100.11920.09730.0755
3.72 9.16 0.9931
150
6080100120
0.07620.05470.04100.0299
10.67008.10006.61005.780
0.12190.10320.08460.0659
2.38 10.73 0.9964
180
6080100120
0.08890.06250.04560.0325
10.26007.81006.41005.600
0.15350.12950.10560.0817
2.72 8.37 0.9971
125
Langmuir Isotherm for the Adsorption of Methyl Violet Dyefrom Aqueous Solution onto BGA
Figure 54
Table 53
126
Langmuir Isotherm for the Adsorption of Acid Blue Dyefrom Aqueous Solution onto BGA
Timein
minutes
InitialConcentration
in mg/l1/Ce m/x
SeparationFactor
RL
Interceptk1/ k1
1Slope1/ k1
1CorrelationCoefficient
r2
10
6080
100120
0.03570.02300.01620.0133
15.6313.6413.0011.11
0.24430.19520.16250.1392
9.16 0.00862 0.7789
20
6080
100120
0.03750.02390.01680.0137
15.0013.0512.3810.61
0.23320.18570.15430.1319
8.99 0.00610 0.9563
30
6080
100120
0.03950.02610.01790.0141
14.4211.9911.3110.14
0.22180.17610.14600.1247
8.09 0.00629 0.9875
40
6080
100120
0.04410.02730.01860.0146
13.3911.5410.839.72
0.20330.16040.13280.1132
8.34 0.00863 0.9875
50
6080
100120
0.04410.02730.01860.0146
12.9311.1110.008.98
0.17540.13760.11320.0961
7.42 0.00784 0.9888
60
6080
100120
0.05000.03160.02170.0166
12.510.359.298.33
0.16810.13160.10810.0918
6.48 0.00825 0.9966
90
6080
100120
0.05770.03530.02360.0172
11.729.688.678.05
0.13080.10140.08280.0699
6.51 0.0111 0.9999
120
6080
100120
0.06250.04290.02740.0179
11.368.827.887.78
0.14580.11350.09290.0787
5.87 0.0122 0.957
150
6080
100120
0.06820.04620.03060.0194
11.038.5727.4287.290
0.13330.10340.08450.0714
5.32 0.0126 0.9693
180
6080
100120
0.07510.05000.03250.0212
10.718.33
7.2226.86
0.10840.08350.06790.0573
5.02 0.137 0.9847
127
Langmuir Isotherm for the Adsorption of Acid Blue Dyefrom Aqueous Solution onto BGA
Figure 55
128
Table 54
Langmuir Isotherm for the Adsorption of Acid Violet Dyefrom Aqueous Solution onto BGA
Timein
minutes
InitialConcentration
in mg/l1/Ce m/x
SeparationFactor
RL
Interceptk1/ k1
1Slope1/ k1
1
CorrelationCoefficient
r2
10
6080
100120
0.02360.01900.01560.0134
28.3318.2713.9911.03
0.20330.16070.13280.1132
8.4961 0.0065 0.8855
20
6080
100120
0.02460.02070.01620.0144
25.7615.8313.1209.87
0.23320.18570.15430.1311
8.3146 0.0055 0.9913
306080
100120
0.02580.02160.01680.0156
23.6114.8512.3508.93
0.22180.17610.14600.1247
7.6174 0.0059 0.9988
40
6080
100120
0.02830.02260.01750.0179
20.2413.9711.6707.8
0.20330.16070.13280.1132
7.8661 0.00650.9816
50
6080
100120
0.02980.02380.01910.0197
18.8913.2010.4907.21
0.17540.13760.11320.0961
7.4191 0.00780.9888
606080
100120
0.03150.02500.02090.0208
17.7112.5009.5506.94
0.16810.13160.10810.0917
6.4835 0.00830.9966
90
6080
100120
0.3330.02640.02330.0250
16.6711.8708.7506.25
0.13080.10140.08280.0691
6.5069 0.011 0.9999
1206080
100120
0.03540.02790.02620.0288
15.7411.3108.0805.86
0.14580.11350.09290.0785
5.0264 0.0098 0.9990
150
6080
100120
0.03780.02960.03030.0313
14.9110.8007.4905.68
0.13330.10340.08450.0714
4.5919 0.0108 0.9951
180
6080
100120
0.03780.02960.03030.0313
14.9110.8007.4905.68
0.10840.08350.06790.0573
5.0225 0.0137 0.9847
129
Langmuir Isotherm for the Adsorption of Acid Violet Dyefrom Aqueous Solution onto BGA
Figure 56
130
Table 55Langmuir Isotherm for the Adsorption of Methylene Blue Dye
from Dyeing Industrial Effluent onto BGA
Timein
minutes
InitialConcentration
in mg/l 1/Ce m/xSeparation
FactorRL
Interceptk1/ k1
1Slope1/ k1
1
CorrelationCoefficient
r2
106080
100
0.02950.02060.0154
19.1515.9414.2
0.045140.033140.02761
-0.0248 0.002840.9998
206080
100
0.03010.02080.0156
17.9915.6313.92
0.056560.042900.03465
-0.0347 0.003590.9976
306080
100
0.03160.02110.0158
17.6515.3213.65
0.062270.047440.03832
-0.0369 0.00399 0.9957
406080
100
0.03270.02140.0161
17.6515.3213.65
0.065190.046550.04025
-0.0418 0.00419 0.9939
506080
100
0.03330.02170.0163
16.0713.7112.46
0.07320.05590.0425
-0.0429 0.00474 0.9995
606080
100
0.03460.02290.0167
16.0713.7112.46
0.076220.058280.04717
-0.0451 0.00496 0.9999
906080
100
0.03590.02370.0171
15.5213.2412.03
0.082240.062970.05102
-0.0477 0.005380.9999
1206080
100
0.03670.0260.0173
15.2512.0211.83
0.07140.0546
0.04425-0.0336 0.00463 0.9152
1506080
100
0.03830.02650.0177
14.7511.8411.45
0.082650.063290.05128
-0.0412 0.005420.9456
1806080
100
0.03910.02740.0182
14.5211.4911.09
0.08070.06170.0500
-0.0367 0.00525 0.9401
131
Langmuir Isotherm for the Adsorption of Methylene Blue Dyefrom Dyeing Industrial Effluent onto BGA
Figure 57
132
Table 56
Langmuir Isotherm for the Adsorption of Methyl Violet Dyefrom Dyeing Industrial Effluent onto BGA
Timein
minutes
InitialConcentration
in mg/l1/Ce m/x Separation
FactorRL
Interceptk1/ k1
1Slope1/ k1
1
CorrelationCoefficient
r2
106080
100
0.02990.02210.0175
18.8614.3811.67
0.28670.21490.1719
1.5082 0.0017 0.9999
206080
100
0.03110.02290.0188
17.9213.6910.65
0.28720.21540.1723
-0.0362 0.0017 0.9957
306080
100
0.03260.02390.0196
17.0713.0710.21
0.32130.24090.1928
0.2850 0.00190.9957
406080
100
0.03410.02500.0204
16.2912.509.8
0.35830.26870.2149
0.5305 0.0022 0.9957
506080
100
0.04220.03200.0213
13.7810.2709.42
0.80210.60160.4813
4.5459 0.0048 0.9395
606080
100
0.04480.03380.0233
13.279.928.75
0.78990.59250.4739
3.4804 0.0047 0.9669
906080
100
0.04780.03590.0272
12.799.587.9
0.69390.52050.4164
1.2119 0.0042 0.9958
1206080
100
0.05970.04110.0288
11.568.997.66
1.30920.98190.7855
3.4804 0.0079 0.9979
1506080
100
0.06520.04420.0306
11.28.717.42
1.45461.09100.8728
4.1085 0.0087 0.9716
1806080
100
0.07170.05230.0326
10.868.217.21
1.78301.33730.9916
3.8798 0.0107 0.9667
133
Langmuir Isotherm for the Adsorption of Methyl Violet Dyefrom Dyeing Industrial Effluent onto BGA
Figure 58
134
Table 57
Langmuir Isotherm for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
Time inminutes
InitialConcentration
in mg/l1/Ce m/x
SeparationFactor RL
Interceptk1/ k1
1Slope1/ k1
1CorrelationCoefficient
(r2)
106080
100
0.02760.02100.0167
21.115.512.6
0.21630.16230.1298
-0.3390.0013 0.9977
206080
100
0.02960.02130.0171
19.115.212.1
0.30520.22890.1831
3.0579 0.0018 0.9915
306080
100
0.03080.02280.0177
18.213.911.5
0.32590.24450.1956
2.3858 0.0019 0.999
406080
100
0.03330.02520.0183
16.712.811.0
0.44030.33020.2642
3.8827 0.0026 0.9922
506080
100
0.03480.02660.0189
16.011.810.6
0.48830.36620.2929
4.0045 0.0029 0.9966
606080
100
0.04000.02770.0189
14.311.410.6
0.95980.71980.5759
7.4112 0.0058 0.9972
906080
100
0.04200.02900.0204
13.810.99.8
0.89430.67070.5366
5.8561 0.0054 0.9933
1206080
100
0.04440.03040.0212
13.310.69.5
0.98640.73980.5919
5.7337 0.0059 0.9944
1506080
100
0.04710.0320.023
12.910.38.8
0.98410.73810.5905
4.9062 0.0059 0.9998
1806080
100
0.0530.03360.0252
12.129.968.28
1.00000.93670.7493
-0.0368 0.0075 0.9884
135
Langmuir Isotherm for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
Figure 59
136
Table 58
Langmuir Isotherm for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
Timein
minutes
InitialConcentration
in mg/l1/Ce m/x Separation
FactorRL
Interceptk1/ k1
1Slope1/ k1
1
CorrelationCoefficient
(r2)
106080
100
0.027590.020970.01656
21.0515.4812.62
0.21630.16220.1299
-0.3390 0.001298 0.9977
206080
100
0.02960.021250.0171
19.0515.1812.05
0.30520.22890.1831
3.0579 0.001831 0.9915
306080
100
0.030770.022770.01767
18.1813.8611.52
0.32590.24450.1956
2.3858 0.001956 0.9990
406080
100
0.033330.024520.01827
16.6712.7511.04
0.44030.33020.2642
3.8827 0.002642 0.9922
506080
100
0.034780.026560.01893
16.0011.8110.60
0.48830.36620.2929
4.0045 0.00293 0.9966
606080
100
0.04000.02770.0189
14.2911.3810.60
0.95970.71980.5759
7.4112 0.005759 0.9972
906080
100
0.04200.02900.0204
13.7910.999.82
0.89430.67070.5366
5.8561 0.005366 0.9933
1206080
100
0.04440.03040.0212
13.3310.639.46
0.98640.73980.5919
5.7337 0.005919 0.9944
1506080
100
0.04710.0320.023
12.9010.288.83
0.98410.73810.5905
4.9062 0.005905 0.9998
1806080
100
0.0530.03360.0252
12.129.968.28
1.24880.93670.7493
-0.0368 0.007494 0.9884
137
Langmuir Isotherm for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
Figure 60
138
4.9.2 Freundlich Adsorption Isotherm
The Freundlich isotherm is an empirical equation that can be used for heterogeneous
systems with the interaction between the adsorbate and the surface of the adsorbent
(Vargas et al., 2011). This model can be successfully adopted to almost all physical
adsorption process. The empirical equation proposed by Freundlich is,
x/m = Kf Ce1/n
Taking log on both side and rearranging, the linear form of the Freundlich isotherm
(Freundlich, 1906; Renugadevi et al., 2011) is given by the following equation:
log x/m = logKf + 1/n log Ce
where,
x = amount of dye adsorbed (mg/l)
m = amount of adsorbent (mg)
Ce = equilibrium concentration of dye adsorbed on BGA(mg/g)
Kf and 1/n are Freundlich constants, which are related to the adsorption capacity and
adsorption intensity respectively and x/m is the amount of adsorbate at equilibrium.
The Freundlich adsorption isotherm plots are obtained by plotting log x/m vs log Ce
for different concentration (60, 80, 100 and 120mg/l) of the dye solutions. The plots
obtained are linear shows the applicability of Freundlich adsorption isotherm for the
removal of the dyes from aqueous solution and from dyeing industrial effluent using BGA
as an adsorbent. The corresponding isotherms drawn are given in Figures 61 – 68. The
slope values indicate the adsorption intensity (1/n) and the intercept values give an idea
about the adsorption capacity (Kf). These values are tabulated in the Tables 59 - 66.
The ‘n’ is an empirical parameter that varies with the degree of heterogeneity and is
related to the distribution of dye species on the adsorbent surface. In general, n > 1
illustrates that adsorbate is favourably adsorbed on an adsorbent and higher the ‘n’ value,
stronger the adsorption intensity (Aksu and Balibek, 2010; Chakraborty et al., 2011). In
this study, the value of ‘n’ is greater than unity, indicating the favourable adsorption of the
dyes (MB, MV, AB and AV) onto BGA (Ahmad and Kumar, 2010) and a physical process
(Sen et al., 2011). The value of ‘n’ lies between 2 and 3 indicates an effective adsorption
(Satish Patil et al., 2011).
139
The value of the Freundlich constant, Kf represents the degree of adsorption
(Chakraborty et al., 2011) and higher values of Kf confirm the easy uptake of adsorbate
from the solution. The correlation coefficient (r2) confirms the validity of Freundlich
adsorption isotherm with the experimental data.
Similar results were obtained for the adsorption of methylene blue onto a biomass-
based activated carbon (Mittal et al., 2010) and acid violet onto various low cost
adsorbents (Kannan et al., 2008).
140
Table 59
Freundlich Isotherm for the Adsorption of Methylene Blue Dyefrom Aqueous Solution onto BGA
Timein
minutes
InitialConcentration
in mg/llog Ce log x/m
Interceptlog Kf Kf
Slope1/n n
CorrelationCoefficient
r2
10
6080
100120
0.98861.23961.38601.7641
-0.9977-0.9072-0.9021-0.8200
1.057 0.3009 0.448 2.2 0.9769
206080
100120
0.85611.22381.34831.7221
-0.9762-0.8979-0.8086-0.8712
1.059 0.3467 0.285 3.5 0.6829
306080
100120
0.82411.09341.24481.7094
-0.9720-0.8690-0.8615-0.7829
1.116 0.3275 0.217 4.6 0.9622
406080
100120
0.78891.02281.13071.6614
-0.9967-0.8572-0.7620-0.9967
1.039 0.3539 0.465 2.2 0.5765
506080
100120
0.74800.96851.10701.6310
-0.9597-0.8495-0.7829-0.8114
1.002 0.3671 0.289 3.5 0.6894
606080
100120
0.71000.93851.08491.5993
-0.9600-0.8458-0.7829-0.8114
0.997 0.3691 0.269 3.7 0.7153
906080
100120
0.66460.90631.06031.5530
-0.9556-0.8420-0.7520-0.7380
-1.0635 0.3454 0.310 3.2 0.8619
1206080
100120
0.61280.87160.97561.4853
-0.9516-0.8383-0.7421-0.7476
1.032 0.3562 0.336 2.9 0.8023
150
6080
100120
0.55100.79240.94351.4018
-0.9476-0.8309-0.7389-0.7222
1.043 0.3523 0.329 3.0 0.8757
180
6080
100120
0.48860.74660.90901.3746
-0.9437-0.8273-0.7357-0.7153
1.024 0.3590 0.315 3.2 0.8897
141
Freundlich Isotherm for the Adsorption of Methylene Blue Dyefrom Aqueous Solution onto BGA
Figure 61
142
Table 60
Freundlich Isotherm for the Adsorption of Methyl Violet Dyefrom Aqueous Solution onto BGA
Time inminutes
InitialConcentration
in mg/llog Ce log x/m Intercept
log Kf
Kf Slope1/n
n CorrelationCoefficient
r2
10
6080
100120
1.38721.63831.74961.8447
-1.1472-1.1358-1.0565-0.9980
-1.6038 0.2041 0.3139 3.2 0.9501
20
6080
100120
1.35261.61441.74961.8447
-1.1239-1.1096-1.0107-0.9745
-1.5631 0.2129 0.3099 3.2 0.9678
30
6080
100120
1.31521.53611.66761.8097
-1.1034-1.0386-0.9694-0.9523
-1.5279 0.2116 0.3236 3.1 0.9922
40
6080
100120
1.27321.50451.61791.7878
-1.0835-1.0178-0.9314-0.9309
-1.4904 0.2315 0.3231 3.1 0.9998
50
6080
100120
1.22771.44191.55591.7235
-1.0641-0.9782-0.8971-0.8733
-1.5552 0.2159 0.4050 2.5 0.9996
60
6080
100120
1.17591.40011.53311.6757
-1.0457-0.9595-0.8802-0.8382
-1.5506 0.2153 0.4284 2.3 0.9992
90
6080
100120
1.17591.35951.46591.6308
-1.0457-0.9420-0.8494-0.8021
-1.6911 0.1862 0.5549 2.0 0.9956
120
6080
100120
1.11811.31331.42821.5917
-1.0281-0.9248-0.8344-0.7909
-1.6026 0.2034 0.5195 2.0 0.9965
150
6080
100120
1.1181.26201.38721.5243
-1.0281-0.9085-0.8202-0.7619
-1.7537 0.1732 0.6607 2.0 0.9897
180
6080
100120
1.05111.20411.34101.4881
-1.0112-0.8927-0.8069-0.7482
-1.6334 0.1952 0.6047 2.0 0.9898
143
Freundlich Isotherm for the Adsorption of Methyl Violet Dyefrom Aqueous Solution onto BGA
Figure 62
144
Table 61
Freundlich Isotherm for the Adsorption of Acid Blue Dyefrom Aqueous Solution onto BGA
Time inminutes
InitialConcentration
in mg/llog Ce log x/m Intercept
log Kf
Kf Slope1/n n
CorrelationCoefficient
r2
106080
100120
1.4471.6371.7891.875
-1.1939-1.1348-1.1139-1.0457
-1.6491 0.1845 0.3124 3.2 0.9977
20
6080
100120
1.4261.6201.7751.863
-1.1761-1.1156-1.0927-1.0257
-1.6246 0.1893 0.3125 3.2 0.9984
306080
100120
1.4041.5841.7461.850
-1.1589-1.0788-1.0535-1.0060
-1.6050 0.1961 0.3224 3.1 0.9967
406080
100120
1.3561.5641.73121.8361
-1.1268-1.0622-1.0346-0.9877
-1.4974 0.2189 0.2741 3.7 0.9993
506080
100120
1.3291.5441.6991.808
-1.1116-1.0457-1.0000-0.9533
-1.5443 0.2135 0.3239 3.1 0.9973
60
6080
100120
1.3011.5011.6641.778
-1.0969-1.0149-0.9680-0.9206
-1.5646 0.2022 0.3616 2.8 0.9995
906080
100120
1.2391.4531.6261.762
-1.0689-0.9857-0.9380-0.9058
-1.4484 0.2349 0.3117 3.2 0.9534
1206080
100120
1.20411.36791.56281.7459
-1.0554-0.9455-0.8965-0.8909
-1.3799 0.2322 0.2944 3.4 0.9557
1506080
100120
1.16641.33591.51441.7112
-1.0426-0.9331-0.8709-0.8627
-1.3962 0.2476 0.3274 3.1 0.9234
180
6080
100120
1.12481.30101.48811.6734
-1.0298-0.9206-0.8585-0.8363
-1.3993 0.2468 0.3493 2.9 0.9537
145
Freundlich Isotherm for the Adsorption of Acid Blue Dyefrom Aqueous Solution onto BGA
Figure 63
146
Table 62
Freundlich Isotherm for the Adsorption of Acid Violet Dyefrom Aqueous Solution onto BGA
Time inminutes
InitialConcentration
in mg/llog Ce log x/m Intercept
log Kf
Kf Slope1/n
nCorrelationCoefficient
(r2)
106080
100120
1.6271.7211.8081.873
-1.4523-1.2617-1.1459-1.0426
-4.1018 0.01654 0.6059 1.7 0.9958
206080
100120
1.60841.68501.79181.8409
-1.4109-1.1995-1.1179-0.9943
-3.9889 0.01852 0.5801 1.6 0.9699
306080
100120
1.58911.66581.77471.8062
-1.3731-1.1717-1.0917-0.9509
-4.0441 0.01753 0.5456 1.7 0.9617
406080
100120
1.54771.64551.75691.7482
-1.3061-1.1452-1.0671-0.8921
-3.7160 0.02433 0.5122 1.6 0.8940
506080
100120
1.52541.62441.71921.7048
-1.2762-1.1206-1.0208-0.8579
-3.9721 0.01883 0.4546 1.8 0.8962
60
6080
100120
1.50201.60211.67781.6812
-1.2482-1.0969-0.9800-0.8414
-4.1715 0.015430.4595 1.9 0.9435
906080
100120
1.47711.57851.63211.6021
-1.2219-1.0745-0.9420-0.7959
-4.5114 0.01098 0.3037 2.2 0.8225
120
6080
100120
1.45091.55381.58091.5399
-1.1970-1.0535-0.8745-0.7679
-4.6545 0.00952 0.2107 2.4 0.7117
1506080
100120
1.42281.52741.52281.5052
-1.1735-1.0334-0.8745-0.7544
-4.6254 0.0098 0.1747 2.5 0.6537
180
6080
100120
1.36061.46941.49071.4673
-1.1300-0.9954-0.8597-0.7419
-4.1251 0.01616 0.2684 2.2 0.7697
147
Freundlich Isotherm for the Adsorption of Acid Violet Dyefrom Aqueous Solution onto BGA
Figure 64
148
Table 63
Freundlich Isotherm for the Adsorption of Methylene Blue Dyefrom Dyeing Industrial Effluent onto BGA
Time inminutes
InitialConcentration
in mg/l log Ce log x/m Interceptlog Kf
KfSlope
1/n nCorrelationCoefficient
(r2)
106080
100
1.53011.68691.8115
-1.2822-1.2025-1.1523
-1.9894 0.1368 0.4636 2.2 0.9979
206080
100
1.50811.68121.8068
-1.2550-1.1940-1.1436
-1.8166 0.1626 0.3717 2.7 0.9993
306080
100
1.50061.67541.8020
-1.2467-1.1853-1.1351
-1.8015 0.1651 0.3691 2.7 0.9994
406080
100
1.48521.66951.7922
-1.2299-1.1853-1.1351
-1.7619 0.1717 0.3558 2.8 0.9903
506080
100
1.47711.66351.7872
-1.2219-1.6849-1.1109
-1.5541 0.0115 0.1308 7.7 0.9750
606080
100
1.46071.63871.7771
-1.206-1.371
-1.0955-1.6949 0.0711 0.2897 3.5 0.9991
906080
100
1.44371.62571.7668
-1.1909-1.1219-1.0802
-1.6861 0.1852 0.3443 2.9 0.9977
1206080
100
1.43491.58431.7616
-1.1833-1.0799-1.0729
-1.6359 0.1948 0.3287 3.0 0.8697
1506080
100
1.41681.5771.7508
-1.1688-1.0734-1.0588
-1.6157 0.1988 0.3259 3.1 0.9112
1806080
100
1.40761.56211.7398
-1.1619-1.0603-1.0449
-1.6316 0.1956 0.3456 2.9 0.9037
149
Freundlich Isotherm for the Adsorption of Methylene Blue Dyefrom Dyeing Industrial Effluent onto BGA
Figure 65
150
Table 64
Freundlich Isotherm for the Adsorption of Methyl Violet Dyefrom Dyeing Industrial Effluent onto BGA
Time inminutes
InitialConcentration
in mg/llog Ce log x/m Intercept
logKf
Kf Slope1/n
n CorrelationCoefficient
(r2)
106080
100
1.52491.65541.7569
-1.2755-1.1578-1.0671
-2.64560.0710 0.8986 1.1 0.9999
206080
100
1.50641.63841.7246
-1.2533-1.1364-1.0274
-2.7992 0.0609 1.0228 1.0 0.9949
306080
100
1.48681.62051.7077
-1.2322-1.1163-1.0090
-2.7213 0.0658 0.9982 1.0 0.9952
406080
100
1.46691.60211.6899
-1.2119-1.0969-0.9912
-2.6508 0.0706 0.9776 1.0 0.9953
506080
100
1.37471.49551.6716
-1.1393-1.0116-0.9741
-1.8461 0.1579 0.5314 1.9 0.9162
606080
100
1.34871.47111.6326
-1.1229-0.9965-0.9420
-1.9427 0.1433 0.6214 1.6 0.9538
906080
100
1.32081.44451.5651
-1.1071-0.9814-0.8976
-2.2340 0.0658 0.8581 1.2 0.9942
1206080
100
1.22401.38621.5402
-1.0630-0.9538-0.8842
-1.7505 0.1071 0.5663 1.8 0.9937
1506080
100
1.18611.35431.5139
-1.0492-0.9400-0.8704
-1.6917 0.1737 0.5465 1.8 0.9937
1806080
100
1.14451.28151.4859
-1.0358-0.9143-0.8579
-1.5908 0.1842 0.5023 2.0 0.9487
151
Freundlich Isotherm for the Adsorption of Methyl Violet Dyefrom Dyeing Industrial Effluent onto BGA
Figure 66
152
Table 65
Freundlich Isotherm for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
Time inminutes
InitialConcentration
in mg/llogCe log x/m Intercept
logKf
Kf Slope1/n
nCorrelationCoefficient
(r2)
106080
100
1.53011.68691.8115
-1.2822-1.2025-1.1523
-1.9894 0.1368 0.4636 2.2 0.9979
206080
100
1.50811.68121.8068
-1.255-1.194-1.1436
-1.8165 0.1626 0.3717 2.7 0.9993
306080
100
1.50061.67541.8020
-1.2467-1.1853-1.1351
-1.8015 0.1651 0.3691 2.7 0.9994
406080
100
1.48521.66951.7922
-1.2299-1.1767-1.1189
-1.7618 0.1717 0.3558 2.8 0.9903
506080
100
1.47711.66351.7872
-1.6849-1.2219-1.1109
-4.4628 0.1153 1.9016 0.5 0.9750
606080
100
1.46071.63871.7771
-1.371-1.206-1.0955
-2.6438 0.0711 0.8734 1.2 0.9991
906080
100
1.44371.62571.7668
-1.1909-1.1219-1.0802
-1.6861 0.1852 0.3443 2.9 0.9977
1206080
100
1.43491.60001.7616
-1.1833-1.0799-1.0729
-1.6540 0.1913 0.3389 3.0 0.8957
1506080
100
1.41681.5771.7508
-1.1688-1.0734-1.0588
-1.6157 0.1988 0.3259 3.1 0.9112
1806080
100
1.40761.56211.7398
-1.1619-1.0603-1.0449
-1.6316 0.1956 0.3456 2.9 0.9037
153
Freundlich Isotherm for the Adsorption of Acid Blue Dyefrom Dyeing Industrial Effluent onto BGA
Figure 67
154
Table 66
Freundlich Isotherm for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
Time inminutes
InitialConcentration
in mg/llogCe log x/m Intercept
logKf
Kf Slope1/n
nCorrelationCoefficient
(r2)
106080
100
1.5591.6781.781
-1.323-1.1897-1.1011
-2.88170.0560
1.0026 1.0 0.9973
206080
100
1.5281.6731.767
-1.2799-1.1813-1.0809
-2.5381 0.0790 0.8197 1.2 0.9918
306080
100
1.5121.6431.753
-1.2596-1.1418-10615
-2.5031 0.0818 0.8240 1.2 0.9983
406080
100
1.4771.0001.610
41.738
2
-1.2219-1.1055-1.0430
-2.228 0.1078 0.6865 1.5 0.9872
506080
100
1.4591.5761.723
-1.2041-1.0722-1.0253
-2.15 0.1164 0.6622 1.5 0.9449
606080
100
1.3981.5571.723
-1.1550-1.0561-1.0253
-1.6987 0.1829 0.3975 2.5 0.9533
906080
100
1.3761.5381.691
-1.1396-1.0409-0.9921
-1.778 0.1689 0.4696 2.1 0.9845
1206080
100
1.3521.5181.674
-1.1248-1.0265-0.9759
-1.7449 0.1747 0.4638 2.2 0.9864
1506080
100
1.3271.4971.638
-1.1106-1.0119-1.9460
-1.8126 0.1632 0.5300 1.9 0.9982
1806080
100
1.2731.4741.598
-1.0835-0.9983-0.9180 -1.7256 0.1781 0.5011 2.0 0.9930
155
Freundlich Isotherm for the Adsorption of Acid Violet Dyefrom Dyeing Industrial Effluent onto BGA
Figure 68
156
4.10 Thermodynamic Studies
Thermodynamic parameters are the fundamental concept in which any chemical
system tends to attain a state of equilibrium, from the non-equilibrium state. The
thermodynamic parameter evaluates the nature of adsorbate and its magnitude during
adsorption process (Milind et al., 2010b). The Gibbs free energy change (∆G), the
enthalpy change (∆H) and the entropy change (∆S) for the adsorption of Methylene Blue,
Methyl Violet, Acid Blue and Acid Violet dyes from aqueous solution onto BGA are
determined using the following relations (Bahl et al., 2005).
Kc = qe / Ce
where,
Kc is the equilibrium constant
qe is the amount of dye adsorbed at equilibrium
Ce is the equilibrium concentration of dye adsorbed on BGA
By using the above relation, the value of Kc, the equilibrium constant is determined
and substituted in the following equation (Bahl et al., 2005),
∆G = - RT ln Kc ………………………Equation (A)
where,
R is the gas constant (8.314 J mole-1K-1) and
T is the Temperature in Kelvin
∆G values for the adsorption of the MB, MV, AB and AV dyes onto BGA adsorbent
are calculated by using the equation A. The Gibbs-Helmholtz equation (Bahl et al., 2005)is given below
∆G = ∆H - T∆S …………………………Equation (B)
From the equations A & B, the following relation is obtained,
ln Kc = - (∆H/ RT) + (∆S/ R)
157
Adsorption of Methylene Blue, Methyl Violet, Acid Blue and Acid Violet dyes using
500mg of the adsorbent BGA and 100ml of the dye solutions containing 100mg/l of the dye
at pH 7.0 ± 0.2 was carried out by varying the temperature (295K, 305K and 315K). The
Vant Hoff’s plots are obtained by plotting 1/T vs ln Kc (Figures 69 – 72). Enthalpy change
∆H and entropy change ∆S are obtained from the slope and intercept of the Vant Hoff’s
plots respectively. ∆G, ∆H and ∆S values obtained in this study are given in Table 67.
The negative values of the free energy change (∆G) indicate the feasibility and the
spontaneous nature of the adsorption, with respect to all the dyes used in this study.
The term ∆H indicates the heat change associated with the overall adsorption process. The
positive ∆H values imply that the adsorption of MB, MV, AB and AV dyes from aqueous
solution using adsorbent BGA is an endothermic process (Ma et al., 2012). The magnitude
of ∆H may give an idea about the type of adsorption. Basically, the heat evolved during
physical adsorption is in the range of 2.1-20.9kJ/mol and the heat of chemical adsorption
generally falls into a range of 80-200 kJ/mol (Chakraborty et al., 2011). The values of ∆H
for the adsorption of MB, MV, AB and AV dyes are given in Table 67, which indicate that
adsorption of these dyes would be attributed to physical adsorption.
The positive ∆S values obtained shows an increase in the randomness at
dye – BGA adsorbent interface which could possibly remove some of the adsorbed water
molecules from the adsorbent surface leading to higher dye removal (Rehman et al.,2012).
Similar results were obtained for the removal of methylene blue dye from aqueous
solution using the adsorbents rice husk (Safa and Bhatti, 2011), teak tree bark powder
(Satish Patil et al., 2011) and crystal violet dye from aqueous solution using the adsorbent
Opal (Ma et al., 2012).
158
Table 67
Thermodynamic Parameters for the Removal of Dyes from Aqueous Solution using Blue-Green Algae
Name of theDyes
Temperature(K) 1/T
qemg/g
cemg/g KC lnKC
∆GkJmol-1
∆HkJmol-1
∆SJmol-1K-1
MethyleneBlue
295 0.00339 87.84 12.16 7.2237 1.9774 -4.849821.1965 88.7443305 0.00328 91.89 8.11 11.3305 2.4275 -6.1556
315 0.00318 92.57 7.43 12.4589 2.5224 -6.6059
Methyl Violet
295 0.00339 73.17 26.83 2.7272 1.0033 -2.460729.2736 107.2323305 0.00328 78.05 21.95 3.5558 1.2686 -3.2169
315 0.00318 85.37 14.63 5.8353 1.7639 -4.6195
Acid Blue
295 0.00339 51.92 48.08 1.0799 0.0769 -1.886139.6414 135.5700305 0.00328 69.23 30.77 2.2499 0.8109 -2.0563
315 0.00318 75.00 25.00 3.0000 1.0986 -2.8771
Acid Violet
295 0.00339 54.76 45.24 1.2104 0.1910 -4.684532.7931 113.2202305 0.00328 69.05 30.95 2.2310 0.8025 -2.0349
315 0.00318 73.81 26.19 2.8183 1.0361 -2.7135
159
Figure 71 Figure 72
Figure 69 Figure 70
160
4.11 Scanning Electron Microscope and FTIR Spectral Analysis
Scanning Electron Microscope (SEM) Analysis has been a primary tool, for
characterising the fundamental surface morphology of an adsorbent. The surface
morphology of the adsorbent BGA before and after the dye adsorption are observed using
SEM analysis. Scanning Electron Micrograph of the adsorbent BGA and BGA with
adsorbed dye species used in this study are shown in Plate A and Plates B to Irespectively. This clearly indicates that the adsorbent BGA exhibits large number of pores
on the external surface and provides suitable binding sites for the dyes of MB, MV, AB and
AV from aqueous solution and from dyeing industrial effluents.
161
SEM Image of the Adsorbent BGA
Plate A
SEM Image of the Adsorbent with Adsorbed Methylene Blue Dye fromAqueous Solution (Plate B) and from Dyeing Industrial Effluent (Plate C)
Plate B Plate C
162
SEM Image of the Adsorbent BGA
Plate A
SEM Image of the Adsorbent with Adsorbed Methyl Violet Dye from AqueousSolution (Plate D) and from Dyeing Industrial Effluent (Plate E)
Plate D Plate E
163
SEM Image of the Adsorbent BGA
Plate A
SEM Image of the Adsorbent with Adsorbed Acid Blue Dye from AqueousSolution (Plate F) and from Dyeing Industrial Effluent (Plate G)
(Plate F) (Plate G)
164
SEM Image of the Adsorbent BGA
(Plate A)
SEM Image of the Adsorbent with Adsorbed Acid Violet Dye from AqueousSolution (Plate H) and from Dyeing Industrial Effluent (Plate I)
(Plate H) (Plate I)
165
FTIR Spectral Analysis
Infrared Spectrum is an important record which gives sufficient information about the
structure of the organic compounds. The position of the peak or the band is used to identify
the presence of a particular functional group present in the compound. The infrared spectra
of the adsorbent BGA is shown in Figure 73.
The spectral data are assigned as below: (Sharma, 2012)
A broad and strong band stretch in the region between 3200cm-1 and 3600cm-1
indicates the presence of –NH2 groups and free or hydrogen bonded –OH groups.
Band at 1648.27cm-1 corresponds to the presence of -C=O group.
The band obtained at 1482.88cm-1 was due to the symmetric bending of CH3 group.
Band observed at 856.09cm-1 corresponds to ester group vibrations.
The band at 1082cm-1 might be due to P-OH stretching.
The IR spectrum of the adsorbent BGA supported the presence of –OH, -COOH,
–C=O, –NH2 and -P-OH functional groups present on the surface of Blue-Green Algae. The
functional groups present on the biomass Blue-Green Algae surface seems to play an
important role in dye adsorption. The adsorption of Methylene Blue, Methyl Violet, Acid Blue
and Acid Violet dyes onto BGA may be due to formation of hydrogen bonds formed
between the dye molecules and the adsorbent. Hydrogen bonds would occur between
hydroxyl, amine and carboxyl groups present on the adsorbent with the dye molecules
(Yonghui Lin et al., 2011).
166
FTIR Spectrum of the Adsorbent BGAFigure 73
166
FTIR Spectrum of the Adsorbent BGAFigure 73
166
FTIR Spectrum of the Adsorbent BGAFigure 73
167
Adsorption of Methylene Blue Dye onto BGA
BGA
NH2 C OH O H
O
S
N
NNC H 3
C H 3CH 3
C H 3+
Methylene Blue DyeOH H
OH C O N H
BGA
168
Adsorption of Methyl Violet Dye onto BGA
BGA
H N C O O H
H OH
Methyl Violet DyeOH H
OH C O N H
BGA
169
Adsorption of Acid Blue Dye onto BGA
BGA
OH C OH NH2
O
Acid Blue Dye
O H
OH C OH N H
BGA
169
Adsorption of Acid Blue Dye onto BGA
BGA
OH C OH NH2
O
Acid Blue Dye
O H
OH C OH N H
BGA
169
Adsorption of Acid Blue Dye onto BGA
BGA
OH C OH NH2
O
Acid Blue Dye
O H
OH C OH N H
BGA
170
Adsorption of Acid Violet Dye onto BGA
BGA
OH C OH N H
O H
Acid Violet Dye
OH
NH2 C O O H
BGA
170
Adsorption of Acid Violet Dye onto BGA
BGA
OH C OH N H
O H
Acid Violet Dye
OH
NH2 C O O H
BGA
170
Adsorption of Acid Violet Dye onto BGA
BGA
OH C OH N H
O H
Acid Violet Dye
OH
NH2 C O O H
BGA