Hybrid kaolin/TiO_2 composite: Effect of urea addition towards an efficient photocatalyst for dye abatement under visible light irradiation

摘要

Photocatalysis has been recognized as an effective approach for photodegradation of organic pollutants in industrial waste water. Photocatalysis generally employs semiconductor materials as photocatalysts, which is possessing enhanced activity by improving their properties, such as: enhanced light absorption, increased surface areas, and dyes adsorption ability, etc. Hence, aiming towards the development of photocatalysts with improved dye degradation rates, herein, an efficient hybrid kaolin-TiO2 composite which was prepared by a simple wet precipitation method that employing urea as an additive is reported. Primarily, the synergistic effect of urea on the TiO2 phases, light absorption and textural properties, for hybrid kaolin/TiO2 composite is investigated analogously to enhance photocatalytic activity. It is observed that urea addition enhances the formation of TiO2 anatase phase, as confirmed by X-rays diffraction (XRD) patterns. Furthermore, UV-Vis Diffuse Reflectance Spectroscopy (DRS) spectra reveal that the synthesized kaolin/TiO2 composites with the varied amount of urea have the ability to absorb visible light with the band gap ranging from 2.73 to 2.92 eV. The photocatalytic activity of kaolin/TiO2 composite is evaluated by methylene blue dye degradation under visible light irradiation, which exhibits 2.3 times higher performance as compared to pure TiO2. The addition of urea interestingly influences the adsorption ability of kaolin, indicated by methylene blue dye abatement under dark condition. Hence, the study reveals that the optimum amount of urea as an additive and kaolin as an adsorbent substrate to develop hybrid materials can be a potent and efficient strategy for improving photocatalytic performance with such cheap and abundant available materials.