humic science & technology viii march 16-18, 2005 northeastern university boston, ma, usa...
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Humic Science & Technology VIII
March 16-18, 2005Northeastern University
Boston, MA, USA
martina klučákovámartina klučáková pavla žbánkovápavla žbánkovámiloslav pekařmiloslav pekař
Brno University of TechnologyFaculty of Chemistry
Institute of Physical and Applied Chemistry
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
interaction of metal ions with humic acids
toxicity of natural systems
carry on previous study (Cu2+)
etc.
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
lignite mine
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
lignitic humic acid
raw material: South-Moravian lignite
isolation: alkalic extraction (NaOH)
C [at. %]
H[at. %]
N[at. %]
S[at. %]
O[at. %]
COOH
[mmol/g]
total acidity[mmol/g]
40.3
41.0
1.5 0.4 16.8
3.27 4.04normalized on dry ash-free
HA
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
humic sols
humic gelsCo2+
Ni2+
physical & chemical interactions
0.01 - 0.20 M
0.1-1.0 g/L
17 % HA
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
previous results:
0.2 M (Cu2+)
1 g/dm3 (HA)
I = 0.1 M (sol)Cu2+ + HR CuR+
+ H+
2CuR+ CuR2 + Cu2+
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
0.2 M (Co2+)
1 g/dm3 (HA); I = 0.1 M (sol)
0.2 M (Ni2+)
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
conductivity and pH
increases stop in the
same moment
conductivity increases while pH-value is constant
[H+]
1×10-6 mol/L
8×10-7 mol/L
[H+]
3×10-5 mol/L
pH increasing is slower than in the case of
Co2+ & Ni2+
Cu2+
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
MeCl2 Me2+ + 2Cl-
HR + H2O H3O+ + R-
2H2O H3O+ + OH-
Me2+ + 4H2O Me(OH)2 + 2H3O+
Me2+ + HR + H2O MeR+ + H3O+Me2+ + R- MeR+
2MeR+ MeR2 + Me2+MeR+ + HR + H2O MeR2 +
H3O+MeR+ + R- MeR2
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
Ni2+ (0.01M)
0.01M Me2+– conductivity decreases (sol 0.1 – 1 g/L); I = 0.1 M
sol (0.1 g/L)
sol (1 g/L)
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
Ni2+ (0.01 M)
I = 0.5 M (sol 0.1 – 1 g/L) no minimum on pH-curve
sol (1 g/L)Ni2+ (0.20
M)
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
Co2+ (0.01 M)
gel no minimum on pH-curve conductivity only increases (Me2+: 0.01 –
0.20 M)
gel
Co2+ (0.20 M)
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
summary reaction: H2R + Me2+ MeR +
2H+
2nd order kinetic rate equation:
dx / dt = k (a-x) (b-x)
kt = 1 / (b-a) ln [a(b-x) / (b(a-x))]
t = 0 a b 0 ht > 0 a – x b – x x h + 2xt ∞ 0 b – a a h + 2a
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
apparent rate constants: sols (0.1 g/L; I = 0.1 M)
apparent rate constants: gels
c0 [mol/L]
Ni2+ Co2+ Cu2+
0.08 1.46 10-5
7.89 10-5
2.02 10-5
0.10 4.39 10-6
6.38 10-5
1.05 10-5
0.15 1.13 10-6
2.25 10-6
2.66 10-6
0.20 2.98 10-7
8.88 10-7
5.21 10-7
c0 [mol/L]
Ni2+ Co2+ Cu2+
0.08 1.12 10-4
1.78 10-4
1.67 10-4
0.10 7.41 10-5
1.64 10-4
1.56 10-4
0.15 5.23 10-5
9.29 10-5
9.13 10-5
0.20 3.69 10-5
7.92 10-5
4.48 10-5
[m3/mol.s]
[m3/mol.s]
b >> a
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
diffusion from constant source
t = 0
x 0; L c1 = 0
t 0
x = 0 c1 = c1,s = const.
t 0
x = L / 2
c1 / x = 0
one-dimensional diffusion T, p = const.; D D (c)
211
x
cD
t
c
Dt
cm s,12
example: Ni2+
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
diffusion from constant source (24 h)
Def [m2/s] Dtab [m2/s]
Ni2+ 8.18 10-
10
1.32 10-
9
Co2+ 7.98 10-
10
1.46 10-
9
Cu2+ 1.07 10-
9
1.43 10-
9 21
21
1 x
cD
t
c
1
D
Def1,1 cc im
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
diffusion from time-variable source example:
Co2+24 h
0.20 M
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Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA
complex interaction mechanism HA - metal ions
non-ideal kinetics
diffusion-affected interaction with humic gel
…….