Pollutant degradation of different organic dyes using the photocatalytic activity of ZnO@ZnS nanocomposite materials

Abstract

The current work focuses mainly to overcome the low surface properties drawbacks of Zinc oxide (ZnO) by spreading of ZnO nanoparticles on the surface of Zinc sulfide (ZnS) synthesized by sol-gel route using Cetyltrimethylammonium-Bromide (CTAB) as capping agent to form ZnO@ZnS nanocomposites (NCs) materials with new properties gathering between the two nanoparticles materials. ZnO@ZnS is an active semiconductor with high efficiency for removal of many organic dyes and pollutant degradation. Different techniques like XRD, BET, FESEM, PL, Uv-vis spectroscopy as well as photocatalytic activity of ZnO, ZnS and ZnO@ZnS results were investigated to confirm the nanostructure and homogenous distribution of particles inside the matrix. In addition, the scavenger study indicates that all charge carriers and reactive radicals contribute by roughly close extent, which explains the observed increase in the rate of degradation. Catalytic reactivity of ZnO@ZnS NCs exerts the same extent of higher efficiency for removal of methylene blue (MB) as well as Eosin dyes under UV lights. Furthermore, the Chemical Oxygen Demand [COD] study indicates that the majority of dyes were removed. The COD of the dye solution before and after the photo catalytic process was calculated, where it is found that COD reduces from 25.4 ppm for pure methylene blue dye to 11.1 ppm after 90 min and 2.4 ppm after 120 min irradiation by ultra violet applied on ZnO@ZnS NCs. Moreover, the recycled experiments for the photodegredation of eosin dye under ultra violet lights were performed to evaluate the stability of ZnO@ZnS nanocomposites after 5 successive cycles.