Humic Science & Technology VIII March 16-18, 2005 Northeastern University Boston, MA, USA martina klučáková pavla žbánková miloslav pekař Brno University of Technology Faculty of Chemistry Institute of Physical and Applied Chemistry

2 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 (Cu 2+ )  etc.

3 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA lignite mine

4 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] normalized on dry ash-free HA

5 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA humic sols humic gels Co 2+ Ni 2+ physical & chemical interactions M g/L 17 % HA

6 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA previous results: 0.2 M (Cu 2+ ) 1 g/dm 3 (HA) I = 0.1 M (sol) Cu 2+ + HR CuR + + H + 2CuR + CuR 2 + Cu 2+

7 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA 0.2 M (Co 2+ ) 1 g/dm 3 (HA); I = 0.1 M (sol) 0.2 M (Ni 2+ )

8 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 Co 2+ & Ni 2+ Cu 2+

9 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA MeCl 2 Me Cl - HR + H 2 O H 3 O + + R - 2H 2 O H 3 O + + OH - Me H 2 O Me(OH) 2 + 2H 3 O + Me 2+ + HR + H 2 O MeR + + H 3 O + Me 2+ + R - MeR + 2MeR + MeR 2 + Me 2+ MeR + + HR + H 2 O MeR 2 + H 3 O + MeR + + R - MeR 2

10 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA Ni 2+ (0.01M) 0.01M Me 2+ – conductivity decreases (sol 0.1 – 1 g/L); I = 0.1 M sol (0.1 g/L) sol (1 g/L)

11 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA Ni 2+ (0.01 M) I = 0.5 M (sol 0.1 – 1 g/L)  no minimum on pH-curve sol (1 g/L) Ni 2+ (0.20 M)

12 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA Co 2+ (0.01 M) gel  no minimum on pH-curve conductivity only increases (Me 2+ : 0.01 – 0.20 M) gel Co 2+ (0.20 M)

13 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA summary reaction: H 2 R + Me 2+ MeR + 2H + 2 nd 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 h t > 0 a – x b – x x h + 2x t  ∞ 0 b – a a h + 2a

14 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 c 0 [mol/L]Ni 2+ Co 2+ Cu             c 0 [mol/L]Ni 2+ Co 2+ Cu             [m 3 /mol.s] b >> a

15 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA diffusion from constant source t = 0 x  0; L  c 1 = 0 t  0 x = 0c 1 = c 1,s = const. t  0 x = L / 2  c 1 /  x = 0  one-dimensional diffusion  T, p = const.; D  D (c) example: Ni 2+

16 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA diffusion from constant source (24 h) D ef [m 2 /s]D tab [m 2 /s] Ni   Co   Cu   10 -9

17 Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA diffusion from time-variable source example: Co h 0.20 M

18 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  …….

19 thanks