SORPTION OF SULFIDE ON A MACROPOROUS, QUATERNIZED POLY(4-VINYL PYRIDINE) IN ALKALINE-MEDIUM

A newly available, macroporous anion-exchange resin Reillex(TM) HPQ, w hich has about 70% of the pyridine rings quaternized by the addition o f methyl groups, has been used in the chloride form for the sorption o f sulfide from alkaline aqueous medium. Comparative data on sulfide so rption capacity and kinetics in alkaline media are presented for this new resin and a common anion exchange resin Dowex-1-X8, both used in c hloride form. The sulfide sorption capacities of HPQ(Cl-1) and Dowex-1 (Cl-1), activated by treatment with mixed NaCl/HCl solution, are found to be 4.8 and 2.5 mmol S/g (dry), respectively, compared to the respe ctive total exchange capacities of 4.6 and 5.6 mEq/g (dry), indicating that sulfide is predominantly sorbed as univalent HS- on HPQ(Cl-) and as bivalent S2- on Dowex-1(Cl-) this is attributed to the occurrence of nearly 30% of the pyridine sites in HPQ(Cl-) in protonated form, co ntributing to lower pH inside the resin phase as compared to external medium. The chloride/sulfide exchange kinetics, in conditions of parti cle diffusion control and infinite solution volume, are predicted with good approximation by the Nernst-Planck model. Both the chloride and sulfide counterions taking part in the exchange process diffuse very s lowly in the resin, the diffusion coefficients being in the order of 1 0(-10) cm(2)/s, though chloride ions have relatively higher diffusivit y than the sulfide ions.