ION-EXCHANGE PROPERTIES OF THE SULFUR-MODIFIED BIOTITE

The ion exchange behavior of a sulfur-modified biotite towards Pb2+, H g2+, Co2+, Cu2+, Cd2+ and Zn2+ ions has been studied. The ion exchange isotherms of divalent cations were determined and concentration equil ibrium constants as a function of metal loading were analyzed. Sulfur modified biotite exhibits high affinity for Hg2+, Pt2+, Cu2+ and Cd2ions in individual solutions and in the presence of electrolytes. Abou t 200 mg Hg/g uptake in 1.10(-3) M Hg2+ solution and similar to 35 mg Hg/g in groundwater simulant or an alkaline simulant 2 M in NaNO3 + 1 M in NaOH was found. The possibility of a complex ion exchange and pre cipitation mechanism of the sulfur modified biotite towards the soft c ations is proposed.