Activated carbon catalytic oxidation of aqueous p-Nitrophenol solution under microwave irradiation in a trickle bed reactor

The microwave catalytic oxidation of p-Nitrophenol solution is investigated in trickle bed reactor (TBR) to study the disposal effect under such conditions of the pH of solution (1~11), the initial TOC concentration (2~8 g·L^-1), various homogeneous catalysts, and granular activated carbon as catalyst. The results show that mineralization rate of p-Nitrophenol solution reaching up to 88.9% during the optimum condition of TOC concentration of 8 g/L, Fe³⁺ concentration of 15 g/L, the microwave power of 800 W, pH 5, quality ratio of solid/liquid of 20:1, and the irradiation time of 60 min. The removal efficiency of TOC is 11.5% more than activated carbon used as catalyst alone. The mechanism analysis shows that active amorphous iron oxide is formed in and outer surface of the activated carbon under high temperature when the Fe³⁺ salt is dipped into the microwave reactor. The newly formed component is better for microwave adsorbing than the activated carbon.