Magnetically recoverable carboxymethyl chitosan/cerium dioxide/iron oxide tricomponent nanocomposite: A biobased photocatalyst for environmental remediation and antimicrobial applications

Carboxymethyl chitosan (CMCs) is extensively used for wastewater treatment owing to its active functional groups. For improved efficiency, a nanocomposite of two metal oxides, cerium dioxide (CeO 2 ) and iron oxide (Fe 2 O 3 ), was prepared by ball milling. Two loadings (0.15 and 0.3 g) of both metal oxides (CeO 2 and Fe 2 O 3 ) were loaded into CMCs and designated as 0.15CeO 2 /Fe 2 O 3 /CMCs and 0.3CeO 2 /Fe 2 O 3 /CMCs nanocomposites and their photocatalytic activity was evaluated against blank CMCs. CMCs showed flake-like morphology after grinding, which was largely coated by CeO 2 and Fe 2 O 3 . The photocatalytic activity of the nanocomposites was studied under sunlight through the degradation of malachite green (MG) dye under different conditions. The 0.15CeO 2 /Fe 2 O 3 /CMCs nanocomposite was able to degrade the dye completely at 15 mgL -1 after 150 min, while the 0.3CeO 2 /Fe 2 O 3 /CMCs completely degraded in 120 min. The results showed that 400 ppm of the catalyst dose and pH 6 were the optimal conditions for the photocatalytic degradation. For 0.3CeO 2 /Fe 2 O 3 /CMCs, the corresponding constant k values were 0.021, 0.014, and 0.009 min⁻ 1 , respectively. The antibacterial activity was tested against Gram-positive and negative bacteria and the 0.3CeO 2 /Fe 2 O 3 /CMCs showed remarkable antibacterial efficacy. The overall results reveal that the CeO 2 /Fe 2 O 3 /CMCs nanocomposites are efficient photocatalysts for the degradation of MG dyes in wastewater with antibacterial activity and show the potential of alleviating environmental hazards and microbial contamination.