Harnessing synergistic effects in porous carbon/Co-ZnO heterojunction for enhanced visible-light photocatalytic removal of bisphenol A

Abstract

Endocrine-disrupting contaminants, particularly bisphenol A (BPA), are prevalent in aquatic environments, posing severe ecological and health risks that demand efficient remediation strategies. Photocatalysis has emerged as a promising enhanced oxidation technology for the mitigation of such recalcitrant organic pollutants. Herein, we report the hydrothermal synthesis of a CCAC/Co-ZnO nanocomposite, achieved by anchoring cobalt doped ZnO nanoparticles onto activated carbon obtained from Croton caudatus biomass. Characterization studies (XRD, SEM, EDS, HR-TEM, XPS, BET surface area, PL and UV-Vis DRS) validated the optimized nanostructure, and photocatalytic evaluations showed 99.67% BPA breakdown within 60 min under visible light irradiation at optimal conditions. The reaction obeyed pseudo-first-order kinetics (t_1/2 of 12.6 min and k_ap of 0.055 min⁻¹), dominated by hydroxyl radicals (˙OH), and photogenerated holes (h⁺) as primary reactive oxygen species (ROS). LC-MS identified intermediates enabled proposal of a plausible BPA degradation pathway, while reusability studies showed 77.63% efficiency over five cycles, confirming excellent photostability and reusability. Moreover, DFT calculations elucidated improved ROS generation mechanisms, providing mechanistic insights into the degradation processes. These findings provide a viable strategy for designing biomass-derived, visible-light-responsive photocatalysts for sustainable environmental remediation applications.