Fenton-like degradation of sulfamethoxazole in Cu0/Zn0-air system over a broad pH range: Performance, kinetics and mechanism.

• Bimetallic Cu0/Zn0 particle was prepared and used for activate oxygen to form H 2 O 2. • O 2 − was the dominant reactive species in Cu0/Zn0-air system for SMX degradation. • The main reactive oxidant species (ROSs) were affected by oxygen concentration. • The possible mechanism and pathway of SMX degradation were proposed. In this study, a bimetallic Cu0/Zn0 particles were prepared, characterized and used as Fenton-like catalyst for the degradation of sulfamethoxazole (SMX). The results showed that Cu0/Zn0 particles were capable of converting O 2 to H 2 O 2 , O 2 − and OH radicals. In bimetallic Cu0/Zn0 particles, Cu0/Zn0 corrosion cells were formed through the direct contact of Zn0 and Cu0, which not only accelerated the electron transfer from Zn0 to O 2 , leading to the promotion of H 2 O 2 generation, but also enhanced the conversion of Cu2+ to Cu+/Cu0, facilitating the catalytic decomposition of H 2 O 2 to produce O 2 − and OH radicals. SMX could be efficiently degraded in Cu0/Zn0-air system over a broad pH range from 3 to 9, the removal efficiency of SMX and TOC was 87.8% and 45.5%, respectively at following condition: SMX concentration, 20 mg/L; dosage of bimetallic Cu0/Zn0 particles (mole ratio of Zn to Cu was 1:2), 2 g/L; air flow rate, 1.8 L/min; reaction temperature, 25℃ and without adjusting pH. The recycling use of bimetallic Cu0/Zn0 particles leaded to the enhanced degradation of SMX due to the newly formed cuprous oxide (Cu 2 O), which could further catalytically activate O 2. The quenching experiment showed that the concentration of dissolved oxygen could significantly affect the main reactive oxidant species (ROSs). Additionally, the intermediate products of SMX degradation were detected and a possible pathway of SMX degradation as well as the catalytic mechanism of Cu0/Zn0-air system were proposed. [ABSTRACT FROM AUTHOR]