Tailored g-C3N4/CuWO4 nanocomposites for efficient Tetracycline removal under visible light

Abstract

The persistent presence of antibiotic contaminants in water bodies poses a significant environmental and public health challenge, as their stability contributes to antimicrobial resistance. In this study, nanocomposites (NCs) composed of CuWO4 (CW) and g-C3N4 (GCN), referred to as GCN/CW, were synthesized and tested as photocatalysts driven by visible light to degrade tetracycline (TC) in an aqueous system. Graphitic carbon nitride (GCN) nanosheets were prepared through thermal polymerization, while copper tungstate (CW) nanoparticles were synthesized through a co-precipitation approach. The NCs with varying CW loadings (5–50 wt.%) were subsequently fabricated using a hydrothermal method followed by calcination. Characterization of the morphological and structural properties confirmed that CW nanoparticles successfully formed on GCN nanosheets, maintaining the original crystal structure of CW. Optical analysis showed increased visible-light absorption in the NCs compared with the respective pristine materials. Photocatalytic experiments demonstrated that the heterojunction catalysts exhibited significantly improved TC degradation efficiency under visible light, attributed to enhanced charge separation and synergistic interactions between CW and GCN. The photocatalytic performance increased with CW loading, with the optimized composite achieving over 93% degradation within 90 min under alkaline conditions. Reaction parameters, including catalyst dosage, pollutant concentration, and pH, were also investigated, revealing optimal performance at pH 10 with a catalyst loading of 20 mg and a TC concentration of 20 mg l−1. Radical scavenging experiments indicated that •OH, •O2-, and h+ are the key reactive species responsible for the degradation process. The catalyst also exhibited good stability, retaining significant activity after repeated cycles. Optimization could also enable the NC to degrade a wider range of pharmaceutical pollutants in water systems.