Catalytic activity and evaluation of Fe-Mn@Bt for ozonizing coal chemical biochemical tail water

Abstract The purpose of this study was to improve the ozone utilization rate by preparing a high-efficiency ozone catalyst, and establish an effective model to evaluate catalytic oxidation systems. In this study, Fe-Mn@Bt ozone catalyst prepared by a doping-baking method was used to deeply treat the biochemical tail water of coal chemical wastewater. The catalyst had an extremely developed pore structure characterized by SEM. The catalytically active elements inside and on the catalyst in the form of α-Fe2O3 and MnO2 had good stability. The effects of operating conditions, such as ozone dosage, hydraulic retention time, and catalyst dosage, on total phenol and total organic carbon (TOC) removal rate were systematically investigated. Under optimal working conditions, the chemical oxygen demand (COD) after the degradation of coal chemical biochemical tail water was used as the evaluation index to explore the actual utilization rate of ozone. The addition of Fe-Mn@Bt porous catalyst upgraded the actual utilization rate of ozone from 0.14. kgCOD/kgO3 (ozone alone oxidation system) to 0.22 kg COD/kg O3. The mechanism of catalytic oxidation was investigated by adding a free radical inhibitor to a catalytic oxidation system, demonstrating that the dominant processes in a deep degradation system was that the catalysis of ozone-generated hydroxyl radicals by active elements and ozone oxidation. To further evaluate the operating conditions for Fe-Mn@Bt ozone catalyst, the “3E” evaluation system where economy, energy, and environment were the key factors was established and evaluated. At optimal levels, the removal ratios of total phenol and TOC were 58.7% and 53.5%, respectively. Fe-Mn@Bt ozone catalysts can effectively improve ozone utilization rate and has a good application prospect for the advanced treatment of coal chemical wastewater.