Synergistic impact of Cu and MnO2 nanoparticles in Cu/MnO2/chitosan/graphene oxide hybrid nanocomposite for improved antibacterial activity and fast adsorption of environmentally relevant anionic and cationic dyes from industrial wastewater.

Water pollution has become a critical global issue, primarily due to contaminants that originate from industrial activities. The textile and plastic industries discharge synthetic dyes, which pose severe threats to ecosystems and human health. This study explores the fabrication and application of a hybrid nanocomposite (Cu/MnO2/CS/GO) for the efficient removal of both anionic (Congo red, CR) and cationic (Malachite green, MG) dyes from industrial wastewater. Cu/MnO2/CS/GO nanocomposite was synthesized by grafting graphene oxide (GO) onto chitosan (CS), followed by decoration with copper (Cu) and manganese dioxide (MnO2) nanoparticles. The GO/CS matrix provided stable support for the uniform dispersion and stabilization of the active nanoparticles. The nanocomposite achieved remarkable dye removal efficiencies, with 99.86 % for MG at pH 8 and 99.91 % for CR at pH 5. HRTEM, SEM, EDX, FTIR, XRD, and XPS techniques were employed to confirm the successful synthesis and structural integrity of the nanocomposite. Cu/MnO2/CS/GO demonstrated excellent reusability, maintaining its performance over five regeneration cycles. Under optimal conditions, effective removal of CR and MG (97.9-99.6 % ± 1.9-4.1) was achieved from three industrial wastewater samples. Moreover, cytotoxicity tests revealed that the presence of the CS/GO moiety reduced the toxicity of Cu/MnO2 nanoparticles in HEK293 cells. The antibacterial performance of Cu/MnO2/CS/GO was assessed in comparison with Cu/MnO2 alone against both Gram-positive and Gram-negative bacteria, with notably improved activity observed against Staphylococcus aureus and Salmonella enterica serovar Typhi.