Abstract
The resource utilization of red mud (RM) has attracted widespread attention for achieving the waste-to-waste treatment goal. In this work, the RM catalysts were synthesized at different calcination temperatures by a simple method. The calcination temperature had a great effect on catalyst activity in the catalytic combustion of biodiesel wastewater. The RM catalyst calcined at 350 °C (RM350) exhibited the best catalytic activity. The chemical oxygen demand (COD) and COD removal rate of the treated wastewater reached almost 0 mg/L and 100%, respectively. The COD removal rate was significantly higher than 90.703% of the catalyst prepared by α-Fe(2)O(3) at the same calcination temperature. Characterization results showed that the RM catalyst exhibited a high specific surface area of 60.03-64.15 m(2)/g and a well-developed mesoporous structure, as the calcination temperature did not exceed 400 °C, which was beneficial for adsorption and diffusion. Meanwhile, most of the Fe(2)O(3) in the catalyst existed in an amorphous form and was abundantly presented on the catalyst surface, significantly lowering the reduction temperature of the catalyst and enhancing its reducibility. Furthermore, the α-Fe(2)O(3) in the catalyst had higher dispersion, leading to an increase in utilization efficiency.