Journal of hazardous materials | 2019

Highly efficient and irreversible removal of cadmium through the formation of a solid solution.



Sulfur-containing materials are very attractive for the efficient decontamination of some heavy metals. However, the effective and irreversible removal of Cd2+, coupled with a high uptake efficiency, remains a great challenge due to the relatively low bond dissociation energy of CdS. Herein, we propose a new strategy to overcome this challenge, by the incorporation of Cd2+ into a stable ZnxCd1-xS solid solution, rather than into CdS. This can be realised through the adsorption of Cd2+ by ZnS nanoparticles, which have exhibited a Cd2+ uptake capacity of approximate 400\u202fmg\u202fg-1. Through this adsorption mechanism, the Cd2+ concentration in a contaminated solution could effectively be reduced from 50\u202fppb to <3\u202fppb, a WHO limit acceptable for drinking water. In addition, ZnS continued to exhibit this noteworthy uptake capacity even in the presence of Cu2+, Pb2+, and Hg2+. ZnS displayed high chemical stability. Particles aged in air for 3 months still retained a> 80% uptake capacity for Cd2+, compared with only 9% uptake capacity for similarly-aged FeS particles. This work reveals a new mechanism for Cd2+ removal with ZnS and establishes a valuable starting point for further studies into the formation of solid solutions for hazardous heavy metal removal applications.

Volume None
Pages \n 121461\n
DOI 10.1016/j.jhazmat.2019.121461
Language English
Journal Journal of hazardous materials

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