CuO and ZnO co-anchored on g-C3N4 nanosheets as an affordable double Z-scheme nanocomposite for photocatalytic decontamination of amoxicillin

[Display omitted] •Double Z-scheme CuO and ZnO co-anchored on thermally-exfoliated g-C3N4 was prepared.•CZ@T-GCN exhibited a high catalytic activity in coupling with simulated solar light.•Complete amoxicillin degradation was achieved after 120 min treatment by CZ@T-GCN photocatalytic process.•CZ@T-GCN activity was diminished marginally after 5 consecutive tests.•CZ@T-GCN/Vis indicated an excellent performance in the treatment of pharmaceutical wastewater. In this study, both CuO nanoparticles and ZnO nanorods were anchored on thermally-exfoliated g-C3N4 nanosheets (denoted as CZ@T-GCN) via isoelectric point-mediated annealing process as a novel nano-photocatalyst towards degradation of amoxicillin (AMOX). The features of prepared materials were characterized using BET, UV–vis DRS, XRD, FT-IR, XPS, FE-SEM, TEM, EIS and transient photocurrent techniques. These analyses demonstrated the successful formation of heterojunctions between components of CZ@T-GCN nanocomposite, which reflected in significantly increased electron-hole separation and enhanced degradation of AMOX as compared with pure substances. The investigation of influential operative parameters confirmed that the complete removal of AMOX could be attained under catalytic dosage of 0.9 g L−1 and pH of 7.0 within 120 min simulated sunlight illumination. Generation of OH upon illumination of catalysts was verified by terephthalic acid photoluminescence (TPA-PL) spectroscopy. Also, trapping tests proved that OH and O2− were the major reactive radicals in AMOX decontamination. A novel double Z-scheme mechanism as well as a tentative pathway for fractionation of AMOX by CZ@T-GCN photocatalytic system were proposed in details. Only a marginal decrease in photocatalytic activity occurred after 5 consecutive tests. In an attempt to study the industrial applicability of catalyst, more than 79 % COD and 63 % TOC were eliminated under optimum conditions during 120 min illumination and the biodegradability of treated wastewater was also improved.