Visible-light-triggered persulfate activation by CuCo2S4 modified ZnO photocatalyst for degradation of tetracycline hydrochloride

In the present work, a series of binary nanocomposites based on ZnO and CuCo2S4 were synthesized through a hydrothermal approach and the corresponding phase, chemical composition, morphology, surface, and optical properties were thereafter characterized. The photocatalytic performance of the materials was explored in the presence of persulfate ions (PS) under visible light for degradation of a medicine, tetracycline hydrochloride (TC), and pollutants including methylene blue, rhodamine B, and methyl orange. Among the photocatalysts, the ZnO/CuCo2S4 (20%) sample exhibited outstanding visible-light-triggered performance for the removal of the organic pollutants of choice. The rate constants of TC oxidation in the ZnO/CuCo2S4 (20%)/PS system were respectively 30.6, 18.9, 16.7, and 7.3 folds higher than the ZnO, PS, ZnO/PS, and ZnO/CuCo2S4 (20%) systems. The leading degradation pathway was established following the results obtained from quenching experiments and a mechanism was proposed for TC degradation through ZnO/CuCo2S4 (20%)/PS system. The findings revealed the importance of heterojunction construction and band energy concordance in the binary system and highlighted the weighty role of persulfate ions in enhanced oxidative removal of the selected pollutants.