Biosorption of Cr(VI)_ and Cr(III)_Arthrobacter species
  The biosorption of Cr(VI)_ and Cr(III)_ Arthrobacter species (Arthrobacter globiformis and Arthrobacter oxidas) was studied simultaneous application dialysis and atomic absorption analysis. Also biosorption of Cr(VI) in the presence of Zn(II) during growth of Arthrobacter species and Cr(III) in the presence of Mn(II) were discussed. Comparative Cr(VI)_ and Cr(III)_ Arthrobacter species shown, that Cr(III) was more effectively adsorbed by both bacterium than Cr(VI). The adsorption capacity is the same for both the Chromium-Arthrobacter systems. The biosorption constants for Cr(III) is higher than for Cr(VI) 5.7-5.9- fold for both species. Comparative Freundlich biosorption characteristics Cr(VI) Arthrobacter species of living and dry cells shown, that capacity(n) is in both cases the same(1.25,1.35). Dry cells have larger biosorption constant for both species, than living cells. Biosorption characteristics (K) and (n) for A. oxidas are without Mn(II) and in the presence of Mn(II) 2.6 x 10-4 (K), 1.37 (n) and 2.4 x 10-4 (K), 1.41 (n) respectively; for A. globiformis without Mn(II) and in the presence of Mn(II) 2.0 x 10-4 (K), 1.23 (n) and 1.9 x 10-4 (K), 1.47 (n) respectively. Thus, Biosorption characteristics did not change in the presence of Mn(II) ions.. It was shown, that bioavailability increases in the presence of Zn ions in both cases. (for Cr(VI)-Arthrobacter globiformis and for Cr(VI)- Arthrobacter oxidas). Biosorption characteristics (K) and (n) for A. oxides in the absence and in the presence of Zn(II) are 4.6 x 10-4 (K), 1.25 (n) and 6.6 x 10-4, 1.08 (n) respectively, for A. globiformis without Zn(II) and in the presence of Zn(II) 3.4 x 10-4 (K), 1.35 (n) and 8.1 x 10-4 (K), 1.19 (n) respectively; n values did not change. But for Cr(VI)-Arthrobacter globiformis increase is more significant. 
E.Gelagutashvili, E.Ginturi D.Pataraia, M.Gurielidze
physics.chem-ph