Chitosan-Encapsulated Nano-Bentonite/g-C 3 N 4 Hybrid Beads for Visible-Light-Driven Photocatalytic Degradation of Methylene Blue and Reduction of Cr(VI)

The escalating discharge of organic pollutants into aquatic systems necessitates high-performance, easily recoverable photocatalysts. This study synthesized a novel chitosan-encapsulated bentonite-g-C3N4 (Bent-GCN/CS) via a simple ionotropic gelation method to overcome the limitations of traditional powder-based systems. Comprehensive characterization using FTIR, XRD, SEM, and UV-Vis DRS confirmed the successful encapsulation of the Bent-GCN framework within the chitosan matrix. The photocatalytic performance was evaluated under UV-Vis irradiation, where the photocatalyst achieved an 87% reduction of Cr(VI) and 83% degradation of methylene blue (MB) within 100 mins. This enhanced activity is attributed to the synergistic interaction between chitosan and the Bent-GCN framework, which improves pollutant adsorption, facilitates effective charge carrier separation, and promotes reactive oxygen species (ROS) generation. Notably, UV-Vis DRS analysis revealed a bandgap reduction from 2.46 eV to 2.11 eV after encapsulation, significantly boosting visible-light absorption. Furthermore, the Bent-GCN/CS catalyst demonstrated excellent structural stability and reusability over repeated cycles. These results highlight the composite as a promising, sustainable, and efficient material for wastewater treatment and environmental remediation.