je ournal of nvironment & biotechnology research vinanie ... · irvingia gabonensis seeds were...

Journal of

Environment & Research VINANIE PUBLISHERS

Removal of Mn(II) from aqueous solution by Irvingia gabonensis immobilized Aspergillus sp. TU-GM14: Isothermal, kinetics and thermodynamic studies

Adeogun A Idowu,1,3,* Omeike Sunday,2 Kareem Sarafadeen Olateju2

1 Department of Chemistry, Federal University of Agriculture, Abeokuta, Nigeria2 Department of Microbiology, Federal University of Agriculture, Abeokuta, Nigeria3 Electrochemical Pollution Control Division, CSIR- Central Electrochemical Research Institute. Karaikudi 630006, India

ORIGINAL RESEARCH ARTICLE

ABSTRACT Irvingia gabonensis immobilized Aspergillus sp. TU-GM14 was used for the removal of Mn2+ from aqueous

solution in batch system. Effect of biosorption variables such as pH, adsorbent dosage, contact time and initial metal ion concentration were investigated. Experimental data obtained from batch equilibrium studies were subjected to two-parameter (Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich (D-R)) and three-parameter (Redlich-Peterson (R-P), Sips, Koble-Corrigan and Toth) isotherm models. The experimental data were fitted to the isotherms with R2 > 0.9. The biosorption energy (E) from the D-R isotherm was found to be 0.13 kJ/mol, which indicates physisorption favoured process. Kinetic data were analysed with nth-order, modified second-order, Avrami and Elovich kinetic models. Both nth and modified second-order kinetic models best fitted the data with coefficient of determination (R2) above 0.999 along with average relative and hybrid errors lower than 5%. Intraparticle diffusion model analysis showed that the biosorption process occurs in two stages as rapid and slow phases. The calculated thermodynamics parameters (∆Go,∆Ho and ∆So) indicated that the process is spontaneous and endothermic in nature.

KEYWORDSAspergillus sp; biosorption; Isothermal; Irvingia gabonensis; kinetics; thermodynamic

1. INTRODUCTION

Increased industrial application of metals resulted in the discharge of industrial effluents with high concentrations of metals into the environment. This is a major concern as it results in bio-accumulation, toxicity and increased threat to human life (Igwe and Abia, 2003). Metals such as iron, lead, manganese, aluminium etc. are of environmental concern because they accumulate in water bodies and have various effects on aquatic organisms and humans (WHO, 1998). Conventional chemical treatment methods are costly and non-environmental friendly (Crini, 2006). Therefore, the need for new eco-friendly methods of

metal removal from aqueous solution is inevitable. Biosorption is a biological method utilizing several biological materials including microbial cells as viable alternatives to conventional chemical treatment methods. It offers advantages such as minimization of chemical/biological sludge, cost effectiveness and efficiency (Wang and Chen, 2009). Biomass from microbial sources have potentials for the remediation of heavy metal contaminated water because of their ability to accumulate micronutrients such as Cu, Zn and Mn; and non-nutrient metals such as Ni, Cd, Sn and Hg in quantities higher than nutritional requirement (Babel and Kurniawan, 2003). This is attributed to phenolic polymers and melanin present in their cell walls which possess many potential metal-binding sites

www.vinanie.com/jebrBiotechnology

Corresponding author: Adeogun A Idowu

Tel: +23480306126987 Fax: +23480306126987 E. mail: [email protected]

Recieved: 22-09-2015Revised: 15-01-2016Accepted: 24-02-2016Available online: 01-04-2016

Journal of Environment and Biotechnology Research, Vol. 3, No. 1, Pages 1-11, 20161

Idowu et al., Journal of Environment and Biotechnology Research, Vol. 3, No.1, Pages 1-11, 2016

with oxygen-containing groups including carboxyl, hydroxyl, carbonyl and methoxyl groups being particularly important in biosorption (Gadd, 2009). Utilization of the waste material from agriculture for heavy metal remediation can make treatment process economical and solve the solid waste disposal problem. Removal of heavy metals using agricultural waste has been reported. These include; rice husk (Munaf and Zein, 1997), soya bean hulls, cotton seed hulls, rice straw, sugarcane bagasse (Marshall and Champagne, 1995), grape bagasse (Farinella et al., 2008), coconut shell and husk (Hasany and Ahmad, 2006), tea leaves (Malkoc and Nuhoglu, 2007), petiolar felt sheath of palm (Iqbal et al., 2002), maize barn (Singh et al., 2006) and defatted Carica papaya seeds (Adie et al., 2011). I. gabonensis seed coat has been used for the removal of metals from aqueous solution based on its non-toxicity and presence of functional groups for the attachment of the metal ions (Onwu et al., 2014). The use of free cells as biosorbent faced limitations due to small size, stress, disintegration etc. (Ivánová et al., 2010). Hence, there is a need to evaluate improved methods. Immobilization on a stable support increases their sorption effectiveness due to increased stability and the possibility of regeneration (Volesky, 2001). In this study, I. gabonensis immobilized Aspergillus sp. TU-GM14 was used for the removal of Mn2+ from aqueous solution. The effects of pH, biosorbent dosage, initial metal ion concentration and contact time were investigated. The equilibrium parameters were analyzed with two-parameter (Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich (D-R)) and three-parameter (Redlich-Peterson (R-P), Sips, Koble–Corrigan and Toth) isotherm models. Kinetic data were analyzed using nth-order, modified second-order, Avrami, Elovich and Intraparticle diffusion kinetic models. Changes in standard free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) for the biosorption processes were estimated and reported using the thermodynamic equilibrium model.

2. MATERIALS AND METHODS

2.1. Chemicals

All chemicals were of analytical grade. Stock solution of Mn2+ (1000 mg/L) was prepared by dissolving known weight of Mn(NO3)2·6H2O in 1000 mL doubly-deionized water. Experimental solutions were prepared by diluting the stock solution. Solution pH was adjusted using 0.1 M HCl and NaOH solutions and the pH value was determined using a pH meter (Thermo Russell,

USA).

2.1.1. Preparation of spore suspensionAspergillus sp. TU-GM14 was collected from the Mi-crobiology Department of the Federal University of Agriculture, Abeokuta, Nigeria. The strain was main-tained on metal-supplemented Sabouraud dextrose agar, SDA (Biorex) with bi-monthly sub-culture. Spores of Aspergillus sp. TU-GM14 were obtained ac-cording to Hemambika et al. (2011). A 4 day-old cul-ture of the fungal cells was suspended in de-ionized water and centrifuged (Electrothermal, UK) at 6000 rpm and room temperature for 20 minutes. Superna-tant was decanted and precipitated spores were dried in the hot-air oven (Gallenkamp, UK) and weighed to constant mass.

2.1.2. Preparation of matrix and immobilization of biosorbentIrvingia gabonensis seeds were purchased locally and sterilized before use. Matrix was prepared by cross-linking I. gabonensis seed (6 % w/v) with glutaraldehyde solution (2.5% v/v). Mixture was stirred for 10 minutes continuously and the resulting gel injected drop-wise into absolute ethanol solution (100% v/v) and left in solution for 24 h. Fungal spores were immobilized by mixing dried spores (in grams) of Aspergillus sp. TU-GM14 with the gel mixture before dropping in stabilizing solution. Firm immobilized biosorbents formed were dried at 40 °C for 20 minutes in the hot-air oven before use.

2.2. Batch equilibrium studies

About 100 mL of aqueous solutions of known Mn2+ concentration with a predetermined amount of biosorbent were placed in Erlenmeyer flasks in an orbital shaker. The effects of biosorbent dosage, pH, initial metal concentration, and temperature on the removal of Mn2+ were studied. Sample solutions were withdrawn at intervals to determine the residual Mn2+ concentration by using atomic absorption spectrophotometer (Varian Model SPECTRA 220). Three replicas of each experimental readings were obtained and the average used for the calculation. The amount of Mn2+ removed at equilibrium, Qe (mg/g), was calculated as below:

WVCC

Q eoe

)( −= (1)

where Co (mg/L) is the initial Mn2+ concentration and Ce

2

(mg/L) is the concentration of the Mn2+ at equilibrium in the liquid-phase. V is the volume of the solution (L) while W is the mass of the adsorbent (g).

2.2.1. EffectofbiosorbentdosageEffect of biosorbent dosages on the removal of Mn2+ from aqueous solution was studied at different adsorbent doses ranging between 0.4-2.0 g using 100 mg/L of the Mn2+ solution. The Erlenmeyer flasks containing the metal ion solutions of the same initial concentration but different biosorbent dosage were placed on orbital shaker and agitated at 200 rpm. After equilibration, the samples were filtered off and the solutions analyzed for the residual Mn2+.

2.2.2. EffectofpHonbiosorptionprocessTo investigate the effect of pH on the biosorption process, series of experiments were carried out on solutions with initial pH varied between 3 and 9. The pH of the solution was adjusted with 0.1 M NaOH or 0.1 M HCl and measured using pH meter. The concentration of the solutions, biosorbent dosage and temperature were held constant at 100 mg/L, 0.8 g and 30 oC, respectively.

2.2.3. EffectsofmetalionconcentrationandcontacttimeThe effects of initial Mn2+ concentration and contact time on biosorption process were investigated with 100 mL solution comprising initial concentrations between 50 and 250 mg/L in series of Erlenmeyer flasks with fixed amount of biosorbent (0.8 g) and pH 5 placed on orbital shaker at 200 rpm. Samples were withdrawn, filtered and the filtrate was analyzed for the residual metal ion from the aqueous at preset time intervals.

2.2.4. Biosorption isothermsThe equilibrium data from this study were described using eight biosorption isotherm models (i.e. 4 each of two-parameter and three-parameter isotherm models). The two-parameter models used were Langmuir (Langmuir, 1918), Freundlich (Freundlich, 1906), Tempkin, (Tempkin, 1940) and Dubinin and Radushkevich (Dubinin and Radushkevich, 1947). On the other hand, Redlich-Peterson (Redlich and Peterson, 1959), Sips (Sips, 1948), Koble-Corrigan (Koble and Corrigan, 1952) and Tóth (Tóth, 1995) are three-parameter isotherm models. The non-linear regression of the models was performed as earlier reported (Adeogun et al., 2011).

2.3 Biosorption kinetics studies

The procedures for the kinetics studies were basically identical to those of equilibrium tests. The aqueous samples were taken at preset time intervals and the concentrations of the Mn2+ were similarly determined in three replicas and average was used for the calculations. The amount of metal ion removed at time t, Qt (mg/g), was calculated as below:

WVCC

Q tot

)( (2)

where Co (mg/L) is the initial Mn2+ concentration and Ct (mg/L) is the concentration of Mn2+ at time t in the liquid-phase, V is the volume of the solution (L), and W is the mass of the biosorbent (g). In order to investigate the mechanisms of the biosorption process, the nth-order and modified second order kinetic model were used (Ritchie, 1997). Avrami (Avrami, 1940) and Elovich (Zeldowitsch, 1934) models were also applied to experimental data for comparison purposes. Due to the fact that the diffusion mechanism cannot be obtained from the kinetics model, the intraparticle diffusion model (Lin et al., 2011) was also tested. A model is adjudged best-fit and selected based on statistical parameters.

2.3.1 Statistical test for the kinetics dataThe acceptability and hence the best fit of the kinetic data were based on the square of the correlation coefficients R2 and the percentage error function which measures the differences (% SSE) in the amount of the metal ion adsorbed at equilibrium predicted by the models, (Q(cal)) and the actual amount was (i.e. Q(exp)) measured experimentally. The validity of each model was determined by the average relative error (SSE, %) and Hybrid error analysis given by:

2exp)((exp) ))((100% QQQ

NSSE cal (3)

2exp)((exp) ))((100% QQQ

PNHYBRID cal

(4)

where N is the number of data points and P is the number of the parameters in the kinetic equation. Higher value of R2 and the lower value of error imply that the model best fitted the data.

2.4. Desorption studies

The regeneration of the spent biosorbent is necessary


3

for the cost effectiveness of the biosorption. Desorption studies was to investigate the number of cycle a given biosorbent can be reused upon regeneration. About 0.2 g of biosorbent was equilibrated with Mn2+ ion solution for 2 h, it was then filtered off and the filtrate was analyzed for Mn2+ to estimate the amount of metal ion biosorbed. The residue (i.e. metal-loaded biosorbent) was transferred into 250 mL conical flasks. To this, 50 mL of 0.1 M of HCl was added and the mixture was shaken for 2 h. After agitation, the solution was filtered, centrifuged and the concentration of desorbed metal ion in the flasks was determined. This process was repeated until the amount in the adsorbed and desorbed cycles showed a significant reduction.

2.5. Thermodynamics of the biosorption process

The thermodynamics parameters i.e. ∆G°, ∆H° and ∆S° were estimated using the following relation:

do KRTG ln (5)

00

lnRTH

RSKd

(6)

The equilibrium constant, Kd, was obtained from the value of Qe/Ce at different temperature equilibrium study. Van’t Hoff plot of ln Kd against the reciprocal of temperature (1/T), should give a straight line with intercept as ∆S°/R and slope of ∆H°/R.

3. RESULTS AND DISCUSSION

3.1. Batch equilibrium studies

3.1.1. EffectofbiosorbentdosageFigure 1 shows the plot of biosorbent dosage against Mn2+ removal in the biosorption process. As shown in Figure 1, the quantity of the biosorbent increased from 0.4 to 0.8 g, the percentage metal ion removed increased from 81 to 87%. Further increase in the biosorbent dosage resulted in reduction of removal efficiency. The initial increase in the efficiency with increasing biosorbent dosage could be attributed to the increase of total adsorbent surface area and biosorption sites, while the subsequent reduction in the percentage removal at biosorbent dosage above 0.8 g may be attributed to the particle interactions, such as aggregation, resulting from high adsorbent concentrations which lead to a reduction of the active

surface area of the biosorbent (Kakavandi et al., 2015).

Figure 1. Effect of biosorbent dosage on the biosorption of Mn2+ on I. gabonensis immobilized Aspergillus sp. TU-GM14. Condition: pH 5, [Mn2+] = 100 mg/L, Temperature = 30 oC.

Figure 2. Effect of pH on the biosorption of Mn2+ on I. gabonensis immobilized Aspergillus sp. TU-GM140. Condition: Biosorbent dosage = 0.8 g, [Mn2+] = 100 mg/L, Temperature = 30 oC.

3.1.2. EffectofpHonbiosorptionprocessAmong the parameters, pH has significant effect on the performance of the biosorbent as well as the metal ion species present in the solution. Hence, pH is regarded as one of the most influencing parameters in the biosorption process. The result of the effect of pH on the percentage removal of Mn2+ is shown in Figure 2.


4

The removal efficiency increases by increasing the pH of the solution from 2 to 7. The lower removal efficiency at low pH may be attributed to the surface protonation leading to repulsion of Mn2+ or competition of Mn2+

and H+ for the available sites. As the pH increases from 2 to 7, competition for the biosorption sites reduced and more Mn2+ were removed from the solution. As the solution approaches basic pH, precipitation of the metal ion may be responsible for the decrease in the percentage metal ion removed (Vukovic et al., 2011).

3.1.3. EffectofinitialmetalionconcentrationsThe effect of initial metal ion concentration on the biosorption process is shown in Figure 3. The process showed a rapid removal in the first 20 min for all the concentrations studied. The efficiency of the process increases from 4.88 to 24.77 mg/g as the initial metal ion concentration increase from 50 to 300 mg/L. The observed increase in the biosorption capacity as the concentration increases due to the increased driving force of the concentration gradient. As there is no significant difference in the quantity of the Mn2+ after 30 min of the process, a steady-state approximation was assumed and a quasi-equilibrium situation was reached.

Figure 3. Effect of initial metal concentration and contact time on the biosorption of Mn2+ on I. gabonensis immobilized Aspergillus sp. TU-GM14. Condition: Biosorbent dosage = 0.2 g, pH = 5, Temperature = 30 oC.

3.2. Biosorption study

The biosorption equilibrium data obtained at different initial Mn2+ concentrations were described using eight different isotherm models. The equation representing

these models and the parameters are summarized in Table 1; the detail of which have been explained elsewhere (Foo and Hameed, 2010; Adeogun and Balakrishnan, 2015). The acceptability and suitability of the isotherm equation to the equilibrium data were based on the values of the correlation coefficients, R2 estimated from linear regression of the least square fit statistic on Micro Math Scientist software. Figure 4 (a and b) represents the biosorption isotherm for the two parameter and three parameter isotherm models; and the isotherm model parameters are presented in Table 2. The biosorption data were fitted well with the Freundlich, Redlich–Peterson and Khan Isotherm models with the highest R2 in their categories (Table 2). The n value of > 1 and the RL of < 1 obtained for Freundlich and Langmuir isotherms indicates that the biosorption process for Mn2+ was favorable for the investigated biosorbents. The Qmax value of 84.11 mg/g also showed that the biosorbent compared favorably well with other biosorbents (Table 3). The mean biosorption energy E obtained from Dubinin–Radushkevich was 0.127 kJ/mol which is an indication of physisorption dominated processes, similar observation had been reported in the literature (Veli and Alyüz, 2007).

Table 1. Isotherm models used for the study of the biosorption of Mn2+ on Irvingia gabonensis immobilized Aspergillus sp. TU-GM14.

Isotherm name Isotherm model Parameters Langmuir

e

ee bC

bCQQ

1max

Qmax and b

Freundlich Fn

Fe CKQ1

KF and nF ,

Temkin )ln( eT

Te CA

BRTQ

Dubinin–Radushkevich

2

22

11ln

EC

RTExpQQ e

se

Qs and E

Redlich–Peterson

)1( geR

eoe CK

CQQ

Qo, KR and g

Sips

))(1()(

s

s

es

esse CK

CKQQ

Qs, Ks and βs

Koble-Corrigan

)1( K

K

ne

ne

e BCAC

Q

A, B and nK

Khan

KAek

ekke CB

CBQQ

)1(

Qk, Ak and Bk


5

Table 2. Isotherm parameters for the biosorption of Mn2+ on Irvingia gabonensis immobilized Aspergillus sp. TU-GM14.

Isotherm Parameters Values Langmuir Qmax (mg/g) 84.41

b (L/mg) 0.008 RL 0.492 R2 0.997

Freundlich KF (mg/g (mg/L)-1/n) 1.015 nF 1.237 R2 0.998

Tempkin AT (L/g) 0.186 BT (J/mol g/mg) 245.822 R2 0.992

Dubinin–Radushkevich Qs (mg/g) 22.809 E (kJ/mol) 0.127 R2 0.972

Redlich–Peterson Q0 (mg/g) 1.187 KR (mg/g) 0.381 G 0.346 R2 0.998

Sips Qs (mg/g) 50.603 Ks (mg/L)1/βs 0.018 βs 1.156 R2 0.996

Koble-Corrigan A (mg/g) 0.057 B (mg/L)1/n

0.002 nK 2.000 R2 0.988

Khan Qk (mg/g) 25.612 Ak 0.440 Bk (mg/L) 0.027 R2 0.998

3.3. Kinetics of biosorption

The plots of four different kinetic models used to explain the biosorption data are shown in Figure 5 (a – d). The equations for these models i.e. nth order modified and second order (Cheung et al., 2001), Elovich (Zeldowitsch, 1934), Avrami (Avrami, 1940)

and intraparticle diffusion mechanism (Lin et al., 2001) are shown in Table 4; and the details of which have explained elsewhere (Adeogun et al., 2011; Ahmad et al., 2014; Adeogun and Balakrishnan, 2015). From the kinetic parameters for the biosorption shown in Table 5, nth-order kinetic models best fitted the kinetic data, the values of β were approximately unity which is an indication of no pre-adsorbed impurity. The values of Qe obtained from the modified second order model compared favourably well with the experimental values with the estimated errors less than 5%. The behaviour of the Elovich constant shows that the process of biosorption was more than one mechanism.

Table 3. Comparision of biosorption of Mn2+ on I. gabonensis immobilized Aspergillus sp. TU-GM14 with other biosorbent.


6

Figure 4. Isothermal fits for the biosorption process, (a) two-parameter (b) three-parameter models.

Biosorbent Biosorption Capacity (mg/g)

References

Kaolinite 0.446 Yavuz, et al. 2003 Natural zeolite tuff 10.0 Rajic, et al. 2009 Aspergillus niger 19.34 Parvathi, et al. 2007 Gleoothece magna 175.2 Mohamed, 2001 Pseudomonas aeruginosa 22.4 Silva, et al. 2009 Saccharomyces cerevisiae 18.95 Parvathi, et al. 2007 Pristine Tamarindus fruit nut shell 122 Suguna et al. 2010 Acid treated Tamarindus fruit nut 182 Suguna et al. 2010 Corncob biomass 6.54 Adeogun et al., 2011 Oxalic Acid modified corncob 7.87 Adeogun et al., 2011 Rice husk ash 0.1336 Adekola et al., 2014 I. gabonensis immobilized Aspergillus sp. TU-GM14

84.41 Current study

Table 4. Kinetic models for the study of the biosorption of Mn2+ on Irvingia gabonensis immobilized Aspergillus sp. TU-GM14.

Isotherm name Isotherm model Parameters nth-order model

)1(

1

)1(11

n

net tnk

QQ

Qe β, n and k1

Modified Second Order

tk

QQ et2

11

Qe, β and k2

Elovich )ln(1 tQt

α and β

Avrami )1( )( avnavtk

et eQQ kav, and nav

Intraparticle model iidt CtKQ 5.0 Kid and Ci

3.4. Biosorption mechanism

The mechanism of biosorption was investigated by subjecting the data to intraparticle diffusion model. The plots are shown in Figure 6. The linearity of the plot was not over the whole time range rather they exhibit multi-linearity revealing the existence of two successive

biosorption steps. The first stage was faster than the second, and it was attributed to the external surface biosorption referred to as the boundary layer diffusion. Thereafter, the second linear part was attributed to the intraparticle diffusion stage; and this stage was the rate controlling step. Table 6 shows the intraparticle model constants for the biosorption of Mn2+ onto Irvingia gabonensis immobilized Aspergillus sp. TU-GM14. The Kdi values were found to increase from first stage of biosorption toward the second stage. The increase in Mn2+ concentration results in an increase in the driving force thereby increasing the diffusion rate.

3.5. Desorption studies

The biosorption – desorption cycles were studied for economic viability of the biosorbent. Figure 7 showed the percentage biosorption - desorption of Mn2+ from Irvingia gabonensis immobilized Aspergillus sp. TU-GM14. Desorption efficiency of 98.6 to 90.1% was obtained in the first three cycle. A reduction of the efficiency to 70.25 % at the fifth cycles is a clear indication that the biosorbent could be used and reused at least four times. The higher efficiency upon reuse

7


Figure 5. Kinetic fits for the biosorption process (a) nth-order (b) modified second order (c) Elovich and (d) Avrami kinetic models.

8

Idowu et al., Journal of Environment and Biotechnology Research, Vol. 3, No. 1, Pages 1-11, 2016

Table 5. Kinetic parameters for the biosorption of Mn2+ on Irvingia gabonensis immobilized Aspergillus sp. TU-GM14.

Co (mg/L) 50 100 150 200 250 Ce (mg/L) 8.17 15.99 29.23 41.61 50.55 Qexp (mg/g) 5.23 10.50 15.10 19.80 24.93 n-order kinetic Qe (mg/g) 5.16 10.65 14.99 19.78 25.08 Β 1.00 1.00 1.00 1.00 1.00 N 1.35 1.94 1.54 1.32 1.58 kn (1/min) (mg/g)1–n 0.19 0.39 0.24 0.22 0.32 R2 0.999 0.999 0.999 0.999 0.999 %ΔQe SSE 0.13 0.14 0.07 0.01 0.06 %ΔQe HYBRID 0.22 0.24 0.11 0.02 0.10 modified second order Qe 5.30 10.68 15.27 20.17 25.40 Β 0.999 0.999 0.999 0.999 1.000 k2 (min)-1 0.32 0.41 0.36 0.46 0.51 R2 0.999 0.999 0.999 0.999 0.999 %ΔQe SSE 0.13 0.17 0.12 0.19 0.19 %ΔQe HYBRID 0.18 0.24 0.17 0.27 0.27 Elovich α (mg/(g min)) 1083.65 1143.14 1128.95 1161.28 1167.06 β (g/mg) 2.47 1.14 0.77 0.57 0.44 R2 0.997 0.997 0.997 0.996 0.995 %ΔQe SSE 0.25 0.21 0.65 1.09 1.58 %ΔQe HYBRID 0.28 0.24 0.73 1.21 1.75 Avrami Qe (mg/g) 5.12 10.39 14.87 19.70 24.86 k1 x10-2 (min-1)nav 0.12 0.14 0.26 0.20 0.19 nav 1.06 1.05 0.77 0.92 0.95 R2 0.997 0.999 0.999 0.999 0.999 %ΔQe SSE 0.21 0.11 0.15 0.05 0.03 %ΔQe HYBRID 0.24 0.12 0.16 0.06 0.03

Intraparticle diffusion parameters

Co (mg/L) 50 mg/L 100 mg/L 150 mg/L 200 mg/L 250 mg/L K1d (mg/g min-0.5) 0.96 1.97 2.76 3.73 4.73 C1(mg/g) 0.28 0.66 0.89 1.33 1.76 R2 0.954 0.943 0.950 0.939 0.934 K2d (mg/g min-0.5) 0.03 0.03 0.05 0.03 0.02 C2(mg/g) 4.80 10.10 14.29 19.32 24.57 R2 0.938 0.949 0.954 0.930 0.927

Table 6. Intraparticle diffusion parameters for the biosorption of Mn2+ on Irvingia gabonensis immobilized Aspergillus sp. TU-GM14.

Table 7. Thermodynamic parameters for the biosorption of Mn2+ on Irvingia gabonensis immobilized Aspergillus sp. TU-GM14.

Temperature Kd ΔG (kJ/ mol K) ΔH (kJ/mol) ΔS (J/mol) R2 283 0.14 4.63 -40.52 127.32 0.962 293 0.30 2.90 303 0.43 2.11

also suggested recyclability and that acidic medium is very suitable for the extraction of the metals from the spent adsorbent.

Figure 6. Intraparticle diffusion fit for the biosorption process.

Figure 7. Biosorption desorption process.

3.6. Thermodynamic parameters

The free energy change, ΔG° was obtained from Eqns. 5 and 6 according to the van’t Hoff linear plots of ln Kd versus 1/T plot in Figure 8. The thermodynamic parameters are presented in Table 7. Decrease in ΔG° values with increase in temperature is an indication that the biosorption processes is spontaneous and feasible. Positive value of enthalpy change (ΔH°) indicates that the biosorption process is endothermic in nature. Positive value of entropy change shows the increased randomness of the solid-liquid interface during the biosorption processes.

Figure 8. Thermodynamic fit for the biosorption process.

4. CONCLUSIONS

This study revealed an improved biosorption capacity of Mn2+ by Aspergillus sp. TU-GM14 upon its support on Irvingia gabonensis matrix. The biosorption process was found optimum at pH 5 and 8 g/L of biosorbent. The optimum temperature for the operation was 30 °C. Equilibrium isotherm data were fitted very well with the Freundlich, Redlich–Peterson and Khan isotherm models. The maximum biosorption capacity of 84.41 mg/g makes the biosorbent to compare favorably with other reported biosorbents. The kinetics of the process was best explained using a modified second-order kinetics model, with R2 > 0.99. Intraparticle diffusion was not the sole rate controlling factor. The desorption study also indicates that the biosorbent can be used several times with the efficiency restored close to the initial value. The thermodynamic parameters obtained indicate that the process is spontaneous endothermic in nature. Therefore, the present findings suggested I. gabonensis immobilized Aspergillus sp. TU-GM14 as a suitable biosorbent for Mn2+ ions.

REFERENCES

Adekola, F.A., Hodonou, D.S.S. and Adegoke, H.I. (2014) Thermodynamic and kinetic studies of biosorption of iron and manganese from aqueous medium using rice husk ash. Applied Water Science, 5, 1-12.

Adeogun, A.I. and Balakrishnan, R.B. (2015) Kinetics, isothermal and thermodynamics studies of electrocoagulation removal of basic dye rhodamine B from aqueous solution using steel electrodes. Applied Water Science, 6, 1 – 13.

Adeogun A. I. and Balakrishnan R. B. (2015) One-Step synthesized calcium phosphate based material for the removal of Alizarin S dye from aqueous solutions: Isothermal, kinetics and thermodynamics studies, Journal of Applied Nanoscience 5, DOI10.1007/s13204-015-0484-9.


9

Adeogun, A.I., Ofudje, A.E., Idowu M.A. and Kareem, S.O. (2011) Equilibrium, kinetic and thermodynamic studies of the biosorption of Mn(II) ions from aqueous solution by raw and acid-treated corncob biomass. Bioresources, 6, 4117-4134.

Adie, G.U., Unuabonah, E.I., Adeyemo, A.A. and Adeyemi, O.G. (2011) Biosorptive removal of Pb2+ and Cd2+ onto novel biosorbent: Defatted Carica papaya seeds. Biomass Bioenergy Weber, 35, 2517-2525.

Ahmad, M.A., Puad, N.A.A. and Bello, O.S. (2014) Kinetic, equilibrium and thermodynamic studies of synthetic dye removal using pomegranate peel activated carbon prepared by microwave-induced KOH activation. Water Resources and Industry, 6, 18-35.

Avrami, M. (1940) Kinetics of phase changes II: transformation-time relations for random distribution of nuclei. The Journal of Chemical Physics, 8, 212-224.

Babel, S. and Kurniawan, T.A. (2003) Low cost adsorbents for heavy metals uptake from contaminated water. Journal of Hazardous Material, 97, 219-243.

Cheung, C.W., Porter, J.F. and McKay, G. (2001) Sorption kinetic analysis for the removal of cadmium ions from effluents using bone char. Water Resources, 35, 605-612.

Crini, G. (2006) Non-conventional low-cost adsorbents for dye removal: a review. Journal of Bioresource Technology, 97, 1061–1085.

Dubinin, M.M. and Radushkevich, L.V. (1947) Equation of the characteristic curve of activated charcoal, Proceedings of the Academy of Sciences, Physical Chemistry Section, U.S.S.R. 55, 331-333.

Farinella, N.V., Matos, G.D., Lehmann, E.L. and Arruda, M.A.Z. (2008) Grape bagasse as an alternative natural adsorbent of cadmium and lead for effluent treatment. Journal of Hazardous Materials, 154, 1007-1012.

Foo, K.Y., Hameed, B.H. (2010) Insights into the modeling of adsorption isotherm systems. Chemical Engineering Journal, 156, 2-10.

Freundlich, H.M.F. (1906) Over the adsorption in solution. Journal of Physical Chemistry, 57, 385-471.

Gadd, G.M. (2009) Biosorption: Critical review of scientific rationale, environmental importance and significance for pollution treatment. Journal of Chemical Technology and Biotechnology, 84, 13-28.

Hasany, S.M and Ahmad R. (2006) The potential of cost-effective coconut husk for the removal of toxic metal ions for environmental protection. Journal of Environmental Management, 81, 286-295.

Hemambika, B., Rajesh K.V. and Rani, M.J. (2011) Biosorption of heavy metals by immobilized and dead fungal cells: A comparative assessment. Journal of Ecology and the Natural Environment, 3, 168-175.

Igwe J.C. and Abia A.A (2003) Maize cob and husk as adsorbents for removal of Cd, Pb and Zn ions from wastewater. The Physical Science, 2, 83-94.

Iqbal, M., Saeed, A. and Akhtar, N. (2002) Petiolar felt-sheath of palm: a new biosorbent for the removal of heavy metals from contaminated water. Bioresource Technology, 81, 151-153

Ivánová, D., Horvathova, H., Kadukova, J. and Kavulicova, J. (2010) Stability of immobilized biosorbents and its influence on biosorption of copper. Nova Journal of Biotechnology, 10, 45-51.

Kakavandi, B., Kalantary, R.R., Jafari, A.J., Nasseri, S., Ameri, A., Esrafili, A. and Azari, A. (2015) Pb(II) adsorption onto a magnetic composite of activated carbon and super paramagnetic Fe3O4 nanoparticles: experimental and modeling study. CLEAN Soil Air Water, 43, 1157-1166.

Koble, R.A. and Corrigan, T.E. (1952) Adsorption isotherms for pure hydrocarbons. Industrial Engineering Chemistry, 44, 383–387.

Langmuir, I. (1918) The adsorption of gases on plane surfaces of glass, mica and platinum. Journal of American Chemical Society, 40, 1361-1403.

Lin, J., Zhan, Y., and Zhu, Z. (2011): Adsorption characteristics of copper (II) ions from aqueous solution onto humic acid-immobilized surfactant-modified zeolite. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 384, 9-16.

Malkoc, E. and Nuhoglu, Y. (2007): Potential of tea factory waste for chromium(VI) removal from aqueous solutions: thermodynamic and kinetic studies. Separation and Purification Technology, 54, 291-298.

Marshall, W.E. and Champagne, E.T. (1995) Agricultural by products as adsorbents for metal ions in laboratory prepared solutions and in manufacturing wastewater. Journal of Environmental Science and Health. Part A: Environmental Science and Engineering and Toxicology, 30, 241-261.

Mohamed, Z.A. (2001) Removal of cadmium and manganese by a non-toxic strain of the freshwater cyanobacterium gloeothece magna, Water Research, 35, 4405 - 4409.

Munaf, E. and Zein, R. (1997) The use of rice husk for removal of toxic metals from waste water. Environmental Technology, 18, 359-362.

Onwu, F.K., Ngele, S.O. and Elom, N.I. (2014) Biosorption of Ni (II) and Pb (II) ions from aqueous solutions by bush mango (Irvingia Gabonensis) husks. International Journal of Chemistry and Applications, 6, 69-80.

Parvathi, K., Kumar, R.N., and Nagendran, R. (2007) Biosorption of manganese by Aspergillus niger and Saccharomyces cerevisiae. World Journal of Microbiology and Biotechnology, 23, 671-676.

Rajic, N., Stojakovic, D., Jevtic, S., Logar, N.Z., Kovac, J. and Kaucic, V. (2009) Removal of aqueous manganese using the natural zeolitic tuff from the Vranjska Banja deposit in Serbia. Journal of Hazardous Materials, 172, 1450-1457.

Redlich, O. and Peterson, D.L. (1959) A useful adsorption isotherm. Journal of Physical Chemistry, 63, 1024-1026.

Ritchie, A.G. (1997) Alternative to the Elovich equation for the kinetics of adsorption of gases on solids. Journal of Chemical Society - Faraday Transactions, 73, 1650-1653.

Silva, R.M.P., Rodriguez, A.A., De, J.M.G.M. and Moreno, D.C. (2009). Biosorption of chromium, copper, manganese and zinc by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum. Bioresource Technology, 100, 1533-1538.

Singh, K.K., Talat, M. and Hasan, S.H. (2006) Removal of lead from aqueous solutions by agricultural waste maize bran. Bioresource Technology, 97, 2124-2130.

Sips, R. (1948) Combined form of Langmuir and Freundlich equations. Journal of Chemical Physics, 16, 490-495.

Suguna, M.S., Siva, K.N., Venkata, S.M. and Krishnaiah, A. (2010) Removal of divalent manganese from aqueous solution using Tamarindus indica fruit nut shell. Journal of Chemical and Pharmaceutical Research, 2, 7-20.

Tempkin, M.I. and Pyzhev, V. (1940) Kinetics of ammonia synthesis on promoted iron catalyst. Acta Physica Chimca, USSR, 12, 327-356.

Tóth, J. (1995) Uniform interpretation of gas/solid adsorption. Advances in Colloid and Interface Science, 55, 1-239.

Veli, S. and Alyüz, B. (2007) Adsorption of copper and zinc from aqueous solutions by using natural clay. Journal of Hazardous Materials, 149, 226-233.


10

Volesky, B. (2001) Detoxification of metal-bearing effluents: biosorption for the next century. Hydrometallurgy, 59, 203-16.

Vukovic, G.D., Marinkovic, A.D., Skapin, S.D., Ristic, M.Ð., Aleksic, R., Peric-Grujic, A.A. and Uskokovic, P.S. (2011) Removal of lead from water by amino modified multi-walled carbon nanotubes. Chemical Engineering Journal, 173, 855-865.

Wang, J. and Chen, C. (2009) Biosorbents for heavy metals removal and their future. Biotechnology Advances, 27, 195-226.

World Health Organization, WHO. (1998) Aluminum: In guidelines for drinking-water quality, Second Edition, Addendum to Volume 2, Health Criteria and Other Supporting Information Geneva, World Health Organization. pp. 3-13.

Yavuz, O., Altunkaynak, Y. and Guze, F. (2003) Removal of copper, nickel, cobalt and manganese from aqueous solution by kaolinite. Water Research, 37, 948-952.

Zeldowitsch, J. (1934) Über den mechanismus der katalytischen oxydation von CO an MnO2. Acta Physicochemical URSS, 1, 364-449.

11


je ournal of nvironment & biotechnology research vinanie ... · irvingia gabonensis seeds were...

Documents