Method of preparation and application of ZnS and CdS nanoparticles for dechlorination of polychlorobiphenyls in oils
The invention relates to zinc or cadmium nano-materials immobilized on the modified bentonite, methods for their preparation and methods for using them for remediation of oils containing harmful polychlorinated biphenyls (PCBs). A stabilized, chemically reactive zinc or cadmium sulfide nano-material effective for degradation of chlorinated biphenyls compounds in PCB oils, transformers, or capacitors was prepared. The nano-materials are composed of zinc or cadmium sulfide nanoparticles that dispersed on the surface of a modified organo-bentonite. The preferred nanoparticles were zinc sulfides and the preferred surfactant for modification of the Na-bentonite was cetylpyridinium bromide. A method of making the sulfide nano-materials is further disclosed wherein a solution of the metal ion and sulfide ion was added alternatively, to a suspension of the modified bentonite in cyclohexane. A process for reductive chlorination of polychlorinated biphenyls is also disclosed wherein the resulting CdS–bentonite and ZnS–bentonite nano-composites can degrade PCBs from oils after 6 h under UV irradiation.