Enhanced photocatalytic and antibacterial performance of CeO₂-loaded carboxymethyl chitosan nanocomposites

Carboxymethyl chitosan (CMCs) was loaded with two different concentrations of cerium dioxide (CeO₂), specifically 0.3 g and 0.6 g, and compared with CMCs. XRD, FTIR and SEM analyses were used to evaluate the structural and morphological characteristics. The nanocomposites were examined for their photocatalytic degradation of Methylene Blue (MB) dye and antibacterial capabilities. Various parameters, including catalyst concentration, dye concentration, and pH levels, were assessed to determine the photocatalytic degradation efficiency of MB dye. The results demonstrated that the 0.6CeO₂/CMCs nanocomposite outperformed the 0.3CeO₂/CMCs and pure CMCs in terms of photocatalytic performance, achieving complete degradation of MB dye within 210 and 240 min after treatment with 0.3CeO₂/CMCs and 0.6CeO₂/CMCs nanocomposites. The agar well diffusion test was employed to assess the antibacterial activity of the nanocomposites against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. 0.6CeO₂/CMCs nanocomposite exhibited the highest antibacterial effectiveness, with zones of inhibition measuring 29 ± 0.63 mm for E. coli, 28 ± 0.18 mm for P. aeruginosa, 25.5 ± 0.25 mm for S. aureus, and 23.6 ± 0.51 mm for E. faecalis. Additionally, the durability and reusability of the nanocomposites were confirmed after undergoing 5 cycles of MB dye degradation, with only a slight decrease in efficiency. The findings of this study highlight the potential of CeO₂/CMCs nanocomposites as powerful antibacterial and photocatalysts with important implications for environmental and biological applications.