Efficient activation of peracetic acid for abatement of tetracycline by W-doped CuS via regulating copper redox cycling

Recently, activation of peracetic acid (PAA) with the copper-based heterogeneous catalysts has been applied for organic pollutant abatement, yet the efficiency is limited by the sluggish Cu(II)/Cu(I) redox cycling. Regarding that reductive W(IV) can continuously effectively promote the regeneration of Cu(I) via the redox-reversible W(IV)/W(VI) couple, the W(IV) component is introduced to copper sulfide for efficient activation of PAA (simplified as the W-CuS/PAA process). Morphological and structural characterizations validate the incorporation of W(IV) component into the CuS lattice structure. Under neutral conditions, tetracycline (TC) can be completely removed within 30 min with the apparent first-order rate constant 5 times higher than that of the CuS/PAA process. CH3C(=O)OO is demonstrated as the main radical responsible for TC abatement by radical quenching experiment and electron paramagnetic resonance (EPR). The redox properties and electron transfer capacity of CuS are significantly improved by the W(IV) component. The reductive W(IV) and S(–II) components facilitate the Cu(II)/Cu(I) redox cycling with the concomitant generation of reactive radicals. In addition, the influence of various parameters and coexisting anions on TC abatement is systematically investigated. Four degradation pathways of TC are put forward and the toxicity of intermediates is evaluated. The W-CuS/PAA process shows superior reuse performance and excellent adaptability in different water matrices. This study highlights the capability of the W(IV) to modulate the Cu(II)/Cu(I) redox cycle and proposes a feasible activator amelioration strategy for the efficient activation of PAA.