Performance and mechanism of catalytic degradation of benzotriazole in water by Fe2O3-CuO/rCG

Abstract

Iron-copper modified coal gangue(Fe2O3-CuO/rCG) was prepared using coal gangue(CG) as raw material through calcination, acid leaching and metal modification. The morphology and structure of Fe2O3-CuO/rCG were characterized and analyzed, and the degradation efficiency and mechanism of Fe2O3-CuO/rCG system on benzotriazole(BTA) were studied. The results showed that the specific surface area and total pore volume of Fe2O3-CuO/rCG significantly increased after modification. Fe2O3 and CuO were successfully filled inside the pores of materials. The optimal preparation conditions for Fe2O3-CuO/rCG were calcination temperature of 650 ℃, calcination time of 3 hours, and metal ion loading concentration of 0.07 mol/L. The optimal conditions for BTA degradation in Fe2O3-CuO/rCG/H2O2 system were BTA concentration of 30 mg/L, Fe2O3-CuO/rCG dosage of 2 g/L, H2O2 concentration of 7 mmol/L, temperature of 25 ℃, and rotational speed of 240 r/min. After 2 hours of reaction, the highest degradation rate of BTA in system could reach 94.86%, and the removal rates of TOC and TN could reach 87.69% and 84.27%, respectively. The Fe2O3-CuO/rCG coupled Fenton system had two main mechanisms for removing BTA:adsorption and catalytic degradation. Adsorption mainly involved gap filling, ligand adsorption, and hydrogen bonding. During the catalytic degradation process, ·OH and 1O2 were the main active species, with dominated by 1O2. Moreover, the redox cycle of Fe2+/Fe3+ and Cu+/Cu2+ accelerated the generation of active species in Fenton-like system.

Keywords

• coal gangue
• catalyst
• adsorption
• catalytic degradation
• benzotriazole