Improved phenol decomposition and simultaneous regeneration of granular activated carbon by the addition of a titanium dioxide catalyst under a dielectric barrier discharge plasma

Abstract

A catalytic method using titanium dioxide (TiO2) under a dielectric barrier discharge (DBD) plasma was studied to improve the decomposition of phenol adsorbed on granular activated carbon (GAC) and the simultaneous regeneration of the saturated GAC. The TiO2–GAC hybrid was fabricated by an impregnation-desiccation method and characterised by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption isotherms and Boehm titration to investigate its adsorption and catalytic characteristics before and after the adsorption and DBD processes. The adsorption experiments showed that the GAC and TiO2–GAC both followed pseudo-second-order kinetic models with adsorption isotherms that were well represented by the Langmuir model. TiO2–GAC exhibited remarkable catalytic activity, increasing the phenol degradation by 19% and TOC removal by 8.7% relative to GAC in DBD treatment. TiO2–GAC also exhibited better regeneration efficiency than GAC, and the reusability of the hybrid material was examined over four consecutive adsorption-regeneration cycles. The above results may be due to the enhanced generation of active species, such as hydroxyl radicals and hydrogen peroxide, on TiO2–GAC relative to GAC during the discharge process, and the main intermediate products were analysed to explore the mechanisms involved in DBD plasma.