Green synthesis of Cr₂O₃-MCC microcomposite for photocatalytic degradation of Congo Red, Crystal Violet, and Methylene Blue in wastewater treatment

Background: Synthetic dyes such as Congo Red (CR), Methylene Blue (MB), and Crystal Violet (CV) are prevalent wastewater pollutants due to their complex aromatic structures, toxicity, and resistance to biodegradation. Conventional treatment strategies often exhibit limited efficacy, underscoring the need for environmentally benign photocatalytic materials. Methods: A green synthetic strategy was employed to fabricate a Cr₂O₃-MCC microcomposite (MCP) by integrating biogenically synthesized chromium (III) oxide (Cr₂O₃) nanoparticles (NPs)—derived from durian husk aqueous extract—into commercial microcrystalline cellulose (MCC). The phytochemicals in durian husk served as intrinsic reducing and stabilizing agents. The resulting MCP was comprehensively characterized by FE-SEM, TEM, XRD, and FTIR to elucidate morphological, structural, and functional attributes. Findings: The Cr₂O₃ NPs were uniformly distributed across the MCC matrix, enhancing stability and photocatalytic surface interaction. Under natural sunlight, the MCP achieved degradation efficiencies of 81.32 % for CR, 77.53 % for MB, and 56.88 % for CV within 180 min. The enhanced photocatalytic performance was attributed to the synergistic interaction between Cr₂O₃ and MCC, which facilitated efficient charge separation and increased dye adsorption. These findings demonstrate the potential of Cr₂O₃-MCC MCP as a sustainable and cost-effective photocatalyst for advanced wastewater treatment applications.