Efficient activation of peracetic acid by multi-valent Cu₇S₄ for the degradation and detoxication of tetracycline hydrochloride: Cu³⁺ acts as an active site

Compared with the persulfate based advanced oxidation processes (AOPs), peracetic acid (PAA) activation is a novel and promising method for wastewater treatment, on account of its lower pH dependence and generation of fewer toxic by-products. However, achieving effective PAA activation by heterogeneous catalyst remains a challenge. In this work, a copper sulfide (Cu7S4) was synthesized and used to activate PAA, which can effectively degrade tetracycline hydrochloride (TCH). More than 71.3 % of TCH can be removed in 15 min via the Cu7S4/PAA system. The excellent activation properties of Cu7S4 can be ascribed to the maintenance of equivalent to Cu3+/equivalent to Cu2+ and equivalent to Cu2+/equivalent to Cu+ cycles by equivalent to S2- and equivalent to S-n(-). The effects of PAA dosage, Cu7S4 concentration, initial pH, temperature, water environment on TCH degradation and mechanism of degradation were explored. Hydroxyl radical (center dot OH) and organic radical (R-O center dot) were considered as the main radicals for the degradation of TCH. This study reveals that the Cu7S4 with multi-valent Cu, particularly equivalent to Cu3+ as active sites, exhibits excellent performance in activating PAA for TCH degradation and detoxication, which broadens the application prospects of AOPs based on PAA in the remediation of antibiotic wastewater.