TiO2-kaolinite composite photocatalyst for industrial organic waste decontamination

Abstract

The industrially feasible TiO2-clay based photocatalysts are essential to overcome the practical barriers that are intrinsic to currently available clay-based photocatalysts. The present study demonstrates the fabrication of heterogeneous photocatalyst consisting of TiO2 and kaolinite (TKCP) that has shown improved catalytic activity and strength, ensuring industrial viable photocatalyst. TKCP is prepared via an economical method, employing mechanical compression and dehydroxylation, forming TiO2-clay hybrid matrix. Amount of clay primarily determines mechanical strength and photocatalytic efficiency of TKCP where TKCP with the lowest clay percentage results in a homogeneous matrix that consists of tiny TiO2 particles embedded clay sheet-like structure. The TiO2 particles embedded clay sheet-like structure is responsible for the high specific surface area and small pore size, increasing the active surface that is available for effective disintegration of organic contaminants. By increasing clay fraction in TKCP, a significant increase in surface defects can be observed due to large clay fragments and TiO2 agglomerates, which results in flexural strength and catalytic activity decrease. Methylene blue degradation on TKCP with the maximum TiO2 percentage results in the highest pseudo first-order rate constant of 0.58 h−1, exhibiting improved photocatalytic activity due to well-organized matrix and high specific surface area (82.79 m2 g−1). TKCP can be obtained in variable sizes and shapes that ensure dynamic wastewater treatment applications.