Oxidation of sulfamethazine by a novel CuS/calcium peroxide/tetraacetylethylenediamine process: High efficiency and contribution of oxygen-centered radicals

Abstract

Calcium peroxide (CP)-based advanced oxidation processes for water decontamination have stimulated considerable attention due to their inherent merits. Herein, a novel tetraacetylethylenediamine (TAED) coupled CuS/CP (i.e., CuS/TAED/CP) process was tentatively employed for the degradation of sulfamethazine (SMT) in water. Experimental results suggested that peracetic acid (PAA) could be efficiently generated and then activated by CuS in alkaline media, achieving 92.1% removal of SMT in 30 min. Identification of reactive oxygen species (ROS) revealed that the available ROS including hydroxyl radical (•OH), singlet oxygen (1O2), and oxygen-centered radicals (R − O•) together accounted for SMT degradation. Based on quantitative analysis of the relative contribution of involved ROS, R − O• were validated to be the primary reactive species that contributed to 75.2% of SMT removal. Additionally, the role of superoxide radical (O2•−), sulfur species, and calcium hydroxide (Ca(OH)2) were investigated. It was concluded that the O2•− and reductive sulfur species enabled the promoted redox cycle of Cu species, and the Ca(OH)2 generated from CP favored the efficient generation and activation of PAA. Influencing factors like CP dosage, initial pH, and nontarget matrix constituents were also evaluated. Moreover, degradation pathways of SMT were proposed, and the ecotoxicity of these intermediates was predicted. The present work provides a promising and simple approach for the rapid decontamination of antibiotic-polluted water.