ENHANCED PHOTOCATALYTIC DEGRADATION OF METHYLENE BLUE DYE UNDER UV-LIGHT IRRADIATION USING Bi2S3/ZnS AND ZnS/Bi2S3 NANOCOMPOSITIES

Abstract

Pure Bi2S3, ZnS, and different ratios of Bi2S3 to ZnS, and ZnS to Bi2S3 have been prepared by hydrothermal method to investigate their efficiency in the adsorption of a toxic cationic methylene blue (MB) dye from synthetic aqueous solutions, and to prove that the heterojunction addition of zinc sulphide to bismuth sulphide and bismuth sulphide to Zinc sulphide with different ratios (1.0, 3.0, 7.0 wt%) significantly improved their photocatalytic activity and methylene blue dye removal. Photodegradation time, initial dye concentrations, and adsorbent doses respectively have been studied. The optimum conditions of methylene blue (MB) dye adsorption were at a contact time of 120 min, 0.05 g/L of pure Bi2S3, pure ZnS, 1 wt% Bi2S3/ZnS, and 1 wt% ZnS/Bi2S3) in an aqueous solution of pH=7, at room temperature, and the %removal of the dye under these conditions reached about (70%, 60%, 95%, and 91%) respectively, and the dye adsorption kinetic process has been analysed using pseudo-first-order kinetic models. The results presented that the adsorption kinetics of methylene blue (MB) dye followed a pseudo-first-order model very well. FTIR, XRD, XPS, and TEM techniques have been conducted to illustrate the properties and characterizations of the prepared photocatalysts. The noticeable improvement we found in the properties and photodegradation rate of heterostructured photocatalysts compared to single photocatalysts hold considerable promise for the development of the novel as well as for the remediation of the environment.