Modulation of MnO2-BiOCl photocatalyst immobilized in polyvinyl alcohol hydrogel for reusable photodegradation of Rhodamine B and Ibuprofen under visible light

Abstract

The presence of pharmaceutical drugs and organic dyes in water poses significant concerns for both human health and the environment. While photocatalysts offer an effective means of pollutant degradation without generating secondary waste, they are commonly limited by charge recombination and small particle size for large-scale practical use. In this study, BiOCl was chemically deposited on MnO₂ and immobilization in the polyvinyl alcohol hydrogel thin films for the photodegradation of Rhodamine B and Ibuprofen under visible light. The plate-like BiOCl successfully grown between nanoflowers of MnO₂, as proven by scanning and transmission electron microscopy images. Energy dispersive X-ray analysis and Fourier-transform infrared spectroscopy results affirmed the chemical characteristics of BiOCl and MnO₂, while X-ray diffraction patterns confirmed the crystallinity of BiOCl and MnO₂. Optimizing the BiOCl loading, 2:1 in ratio with MnO₂ yielded a PVA thin film with high photocatalytic activity. 99 % of Rhodamine and 97 % of Ibuprofen were degraded in 60 min and 90 min respectively. Even after five recycles, the catalyst maintained over 80 % efficiency for RhB and 70 % for Ibuprofen. The degradation was primarily driven by •O₂⁻ and e⁻ generated by the MnO₂ and BiOCl composite. This study highlights the potential of BiOCl-MnO₂/PVA hydrogel composites for sustainable, reusable, and efficient water treatment applications.