Preparation of the self-accelerating photocatalytic self-cleaning carboxymethyl cellulose sodium-based hydrogel for removing cationic dyes.

Hydrogels loaded with photocatalysts have shown great potential in effectively degrading dye wastewater. In this work, carboxymethyl cellulose sodium-based hydrogels loaded with nitrogen-doped graphene oxide-zinc oxide-zinc peroxide (NGO-ZnO-ZnO2) were synthesized using hydrothermal reaction and in-situ synthesis method. NGO acts as an electron mediator, suppressing the recombination of photoinduced electrons and holes. ZnO2 decomposes to generate hydrogen peroxide (H2O2), promoting a self-enhanced photocatalytic reaction. Carboxymethyl cellulose sodium (CMC) acts as a dispersant, improving the uniformity and stability of NGO-ZnO-ZnO2 within the hydrogel. The results demonstrate that NGO-ZnO-ZnO2 exhibits high photocatalytic degradation efficiency towards methyl orange (MO) (10 mg/L) and rhodamine B (RhB) (50 mg/L), with degradation rates of 99.99 % (200 min) and 99.26 % (160 min), respectively. The carboxymethyl cellulose sodium-based hydrogel achieves a photocatalytic degradation rate of 95.85 % (220 min) for RhB (10 mg/L). After 5 cycles of repeated photocatalytic tests, the degradation efficiency of the hydrogel towards RhB reaches 80.81 %. This work provides a low-cost and convenient method for constructing novel hydrogel carriers with high photocatalytic stability and efficiency.