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