Efficient electrocatalytic degradation of sulfamethoxazole with CuAl-LDO/HGF cathode in a neutral heterogeneous electro-Fenton process

Abstract

In this study, CuAl-LDH precursor was loaded on heat-treated graphite felt (HGF) to obtain CuAl-LDH/HGF. Then, the CuAl-LDO/HGF composite electrode was synthesized by calcination under a high-temperature nitrogen atmosphere. CuAl-LDO/HGF composite electrodes were used to remove sulfamethoxazole (SMX) in a heterogeneous electro-Fenton (hetero-EF) system. Both the hydrophilicity and redox capacity of CuAl-LDO/HGF composite cathode were significantly improved, and the SMX removal effect of CuAl-LDO/HGF in the hetero-EF system was superior to that of HGF. After the preparation conditions and reaction factors were optimized, SMX was completely eliminated within 60 min using the hetero-EF system under nearly-neutral conditions. 69.33% of the total organic carbon (TOC) was removed from the solution after 6 h of reaction. The SMX removal efficiency approached 94.4% after eight reuse cycles. Radical quenching experiments showed that surface hydroxyl radicals (•OH) were crucial to the degradation of SMX in this hetero-EF system. The biological toxicity of SMX and the products generated during its degradation were assessed, and the probable SMX degradation mechanism was also discussed. This work provides a feasible new insight for hetero-EF systems to remove antibiotics from wastewater.