Effect of Temperature on Cu (Se, S) for the Degradation of Methylene Blue in Aqueous Solution

Abstract

Water pollution is one of the biggest problems in the world nowadays. Among various contaminants at about 20% of the water pollution is caused by organic dyes. Organic dye removal from different sources has never been easy and is becoming a major concern for environmental and societal health. Among these organic dyes, cationic methylene blue is highly toxic and can cause great environmental pollution and health effects. In this work, the effect of temperature on sulfur doped copper selenide for degradation of methylene blue was studied. Initially, Cu (Se, S) was synthesized by the hydrothermal method, then the synthesized materials were characterized using X-Ray Diffraction, Scanning Electron Microscopy, Fourier Transform-Infra Red Spectroscopy, Photoluminescence spectroscopy, and UV-Vis Diffuse Reflectance Spectroscopy to determine phase purity, the particles morphology, functional groups, photon recombination, and the degradation efficiency respectively. From the diffraction pattern, it is confirmed the synthesized CuSe was crystalline klomannite hexagonal with no other impurities peaks and Scanning Electron Microscope reveals that synthesized pristine CuSe with smooth surface and relatively symmetrical hexagonal shapes. The optical bandgap of the synthesized samples CuSe, 3% S CuSe, and 5% S CuSe estimated from Diffuse Reflectance Spectroscopy and Photoluminescence spectroscopy measurement were becoming 2.33eV,2.3eV, 2.32eV respectively. 3% S CuSe exhibited a better degradation efficiency of about 46.5% at the initial MB concentration of 10 mgL-1 and with a catalyst dose of 0.05g. This sample was subsequently selected for further temperature studies. The effect of temperature was investigated for the present material ranging from room temperature to 90℃. At a temperature of 70℃, the degradation efficiency is maximum, with the corresponding results of 70% removal of MB, and decrease at 90℃. The kinetic behavior obeyed the Pseudo-first-order degradation kinetics. Finally, the reusability of the present synthesized material was studied for up to 4 cycles and showed suitable reusability towards the MB removal. Therefore, the results of this study indicate that system temperature has a great effect on the photocatalytic activity of CuSe for the removal of methylene blue organic dye.