ZnS nanoparticle gels for remediation of Pb2+ and Hg2+ polluted water.

ZnS nanoparticle (NP) gel networks were used as cation exchange materials for the removal of Pb(2+) and Hg(2+) from aqueous solutions. First, the suitability of the gel as a remediation material was studied by analyzing the mechanism of the cation exchange reaction. ZnS NP gels can exchange with other divalent cations (Pb(2+), Hg(2+)) under mild reaction conditions. The speed of the reaction is influenced by the reduction potential of the incoming cation. The ZnS aerogels can remove Pb(2+) and Hg(2+) from aqueous solutions with a wide range of initial concentrations. For initial Pb(2+) concentrations of 100 ppb, the Pb(2+) concentration can be reduced below the action limit established by the EPA (15 ppb). Under thermodynamically forcing conditions, the water remediation capacity of the ZnS NP aerogels was determined to be 14.2 mmol Pb(2+)/ g ZnS aerogel, which is the highest value reported to date.