Dual-functional xanthan gum/chitosan nanocomposite doped with copper oxide nanoparticles for high-capacity adsorption of methylene blue and methyl orange dyes and antimicrobial applications.

In the current study, a xanthan gum/chitosan/copper oxide nanoparticle (XaG/Ch/CuO-NPs) nanocomposite was synthesized and evaluated as a biosorbent for organic dyes and antimicrobial activity. The resulting XaG/Ch/CuO-NPs nanocomposite was characterized to confirm the successful incorporation and uniform dispersion of CuO-NPs within the nanocomposite. The removal efficiencies of methylene blue (MB) and methyl orange (MO) were investigated as a function of pH, contact time, and dye concentration. Under the optimized conditions, the XaG/Ch/CuO-NPs nanocomposite exhibited high adsorption capacities of 88 and 114 mg g-1 for MB and MO, respectively. The close agreement between experimental data and the pseudo-second-order kinetic model (R 2 = 0.99) suggests that chemical interactions govern the adsorption process. The adsorption equilibrium followed the Langmuir model, suggesting monolayer adsorption on a homogeneous surface. The adsorption capacity retention rate reaches 85% after 5 cycles. The antimicrobial activities of the XaG/Ch and XaG/Ch/CuO-NPs nanocomposite were evaluated against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Streptococcus mutans, and Candida albicans. The findings showed that the XaG/Ch/CuO-NPs nanocomposite exhibited broad-spectrum inhibitory effects against all tested pathogens, with inhibition zones ranging from 15 to 12 mm, whereas the XaG/Ch composite displayed no detectable antimicrobial activity. Overall, the XaG/Ch/CuO-NPs nanocomposite is promising for industrial wastewater purification, offering a sustainable alternative to conventional adsorbents.