humic science & technology viii march 16-18, 2005 northeastern university boston, ma, usa
DESCRIPTION
complexation kinetics. in humic colloidal systems. martina klučáková pavla žbánková miloslav pekař. Brno University of Technology Faculty of Chemistry Institute of Physical and Applied Chemistry. Humic Science & Technology VIII March 16-18, 2005 Northeastern University Boston, MA, USA. - PowerPoint PPT PresentationTRANSCRIPT
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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
…….
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thanks