Synergistic synthesis of Carrisa edulis fruit extract capped heterogeneous CuO-ZnO-HNT composite for photocatalytic removal of organic pollutants

Abstract

Photocatalysis is a promising strategy for treating harmful pollutants in the ecosystem. Recently, the use of semiconductor photocatalysts to remove organic dyes and pharmaceutical drugs from polluted water has gained a lot of interest. In this work, initially, CuO-ZnO composite was synthesized using microwave method utilizing Carrisa edulis fruit extract as capping/stabilizing agent. Secondly, heterogeneous CuO-ZnO-Halloysite nanotube (HNT) photocatalyst have been synthesized via ultrasonication method. The synthesized composite was confirmed by various characterization techniques such as X-ray diffraction (XRD), UV–vis-DRS Spectroscopy (UV–vis-DRS), Fourier-Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscope (FE-SEM), Energy Dispersive X-ray Analysis (EDAX), Brunauer Emmette Teller analysis (BET), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric analysis (TGA) and Zeta Potential. The resultant CuO-ZnO-HNT composite possesses narrow band gap, large surface area with microsphere morphology. Under visible light irradiation, the synthesized composite was evaluated for photocatalytic activity against Congo Red (CR) and Tetracycline (TC). It is observed that within 70 min of irradiation, the 20CZ-HNT composite showed 86 % and 90 % degradation of CR and TC respectively. The reusability test showed that the catalyst was stable even after five cycles. As a result, the CuO-ZnO-HNT composite exhibits great promise for photocatalytic removal of environmental pollutants utilizing visible light.