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

1. 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 VIIIMarch 16-18, 2005Northeastern University Boston, MA, USA

2. why...? • interaction of metal ions with humic acids • toxicity of natural systems • carry on previous study (Cu2+) • etc. Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

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

4. material...? • lignitic humic acid • raw material: South-Moravian lignite • isolation: alkalic extraction (NaOH) normalized on dry ash-free HA Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

5. experimental...? 0.1-1.0 g/L humic sols humic gels 17 % HA Co2+ Ni2+ 0.01 - 0.20 M physical & chemical interactions Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

6. Cu2+ + HR CuR+ + H+ 2CuR+ CuR2 + Cu2+ humic sols previous results: 0.2 M (Cu2+) 1 g/dm3 (HA) I = 0.1 M (sol) Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

7. humic sols 0.2 M (Co2+) 0.2 M (Ni2+) 1 g/dm3 (HA); I = 0.1 M (sol) Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

8. differences... Co2+&Ni2+ Cu2+ conductivity and pH increases stop in the same moment conductivity increases while pH-value is constant D[H+] 1×10-6 mol/L 8×10-7 mol/L D[H+] 3×10-5 mol/L pH increasing is slower than in the case of Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

9. MeCl2 Me2+ + 2Cl- Me2+ + 4H2O Me(OH)2 + 2H3O+ HR + H2O H3O+ + R- 2H2O H3O+ + OH- Me2+ + R- MeR+ Me2+ + HR + H2O MeR+ + H3O+ 2MeR+ MeR2 + Me2+ MeR+ + HR + H2O MeR2 + H3O+ MeR+ + R- MeR2 humic sols Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

10. humic sols Ni2+ (0.01M) sol (1 g/L) sol (0.1 g/L) 0.01M Me2+– conductivity decreases (sol 0.1 – 1 g/L); I = 0.1 M Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

11. humic sols sol (1 g/L) Ni2+(0.01 M) Ni2+(0.20 M) I = 0.5 M (sol 0.1 – 1 g/L)  no minimum on pH-curve Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

12. humic gels gel Co2+(0.01 M) Co2+(0.20 M) gel  no minimum on pH-curve conductivity only increases (Me2+: 0.01 – 0.20 M) Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

13. humic sols & gels summary reaction: H2R + Me2+ MeR + 2H+ t = 0a b 0 h t>0 a – x b – x x h + 2x t ∞ 0 b – a a h + 2a 2nd order kinetic rate equation: dx / dt = k (a-x) (b-x) kt = 1 / (b-a) ln [a(b-x) / (b(a-x))] Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

14. humic sols & gels apparent rate constants: sols (0.1 g/L; I = 0.1 M) b>> a [m3/mol.s] apparent rate constants: gels [m3/mol.s] Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

15. humic gels diffusion from constant source • one-dimensional diffusion • T, p = const.; D D (c) example: Ni2+ Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

16. humic gels diffusion from constant source (24 h) Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

17. humic gels diffusion from time-variable source example: Co2+ 24 h 0.20 M Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

18. conclusions... • complex interaction mechanism HA-metal ions • non-ideal kinetics • diffusion-affected interaction with humic gel • ……. Humic Science & Technology VIII, March 16-18, 2005, Northeastern University, Boston, MA, USA

19. thanks