Characterization of bauxite as a potential natural photocatalyst for photodegradation of textile dye

Abstract

Previous water treatments used are nondestructive and lead to the formation of new type of pollution. Photocatalytic reaction which induced by illumination of semiconductors in suspension was one of the most promising processes for wastewater treatment due to the ability of providing an interface with the aqueous medium and induce an advanced oxidation process. In this study, Malaysian bauxite has been selected as a new potential candidate for photocatalytic degradation. Bauxite powder was undergone heat treatment ranging from 800 to 1000 °C and then was characterized by field emission scanning electron microscope, X-ray diffraction (XRD), Brunauer–Emmett–Teller, ultraviolet–visible–near infrared spectroscopy and suspension absorbance test to determine the existing components and their composition, structure of the powder, band gap energy as well as the photocatalytic efficiency of bauxite in suspension of various concentrations of Reactive Black 5 (RB5) ranging from 5 to 20 ppm. The finding revealed that bauxite possessed slight changes in terms of XRF composition as well as particle size due to thermal process. This is supported by XRD analysis which showed that phase conversion occurred at 800 °C. Heat-treated bauxite possesses low band gap energy (2.04 eV). The photocatalytic activity of raw bauxite suspension was measured after 360 min illumination, and it proved that there was degradation of 67% and 63% from the initial 5 ppm concentration of RB5 using visible and UV lights, respectively. This finding clearly shows that bauxite exhibits good photocatalytic degradation and hence has a promising potential in removing dyes for industrial wastewater.