Remediation of arsenic and lead with nanocrystalline zinc sulfide

摘要

Nanocrystalline (1.7±0.3nm) zinc sulfide with a specific surface area up to 360m ~2g ~1 was prepared from the thermal decomposition of a single-source precursor, zinc ethylxanthate. Zinc ethylxanthate decomposes to cubic zinc sulfide upon exposure to temperatures greater than or equal to 125°C. The resulting zinc sulfide was tested as a water impurity extractant. The target impurities used in this study were As ~(5+), As ~(3+), and Pb ~(2+). The reaction of the nanocrystalline ZnS with Pb ~(2+) proceeds as a replacement reaction where solid PbS is formed and Zn ~(2+) is released into the aqueous system. Removal of lead to a level of less than two parts per billion is achievable. The results of a detailed kinetics experiment between the ZnS and Pb ~(2+) are included in this study. Unlike the instance of lead, both As ~(5+) and As ~(3+) adsorb on the surface of the ZnS extractant as opposed to an ion-exchange process. An uptake capacity of >25mgg 1 for the removal of As ~(5+) is possible. The uptake of As ~(3+) appears to proceed by a slower process than that of the As ~(5+) with a capacity of nearly 20mgg ~1. The nanocrystalline zinc sulfide was extremely successful for the removal of arsenic and lead from simulated oil sand tailing pond water.