Photocatalytic and sonocatalytic dye degradation by sulfur vacancy rich ZnS nanopowder

Photocatalytic dye degradation is one of the simple and convenient ways to eliminate effluents produced by paper, plastic, printing, and textile industries. ZnS is one of the most investigated catalysts on which different modifications are applied. Here, PVP-assisted zinc sulfide (ZnS) nanopowder is prepared hydrothermally. The photoluminescence spectra signify the generated intermediate state which is attributed to sulfur (S) vacancy as obtained from the theoretical analysis. This defect-induced ZnS has shown excellent Rhodamine B (RhB) dye degradation of 95% in 100 min with dye sensitization effect under UV irradiation. Under visible light, the degradation of RhB is only 50% in the presence of ZnS. The sensitization of RhB in the presence of UV light signifies the generation of visible light through the intermediate states caused by S vacancy. However, to eliminate the disadvantage of photocatalysis in highly concentrated wastewater management and expense of UV source, RhB is degraded by sonocatalysis, and 70% of dye is removed within 100 min in the presence of ZnS nanopowder. Therefore, the efficient catalytic dye degradations are achieved employing the minimum amount of ZnS powder.