PHOTOCATALYRIC DEGRADATION OF RHODAMINE B BY CELLULOSE/ZnO COMPOSITE FILM

The discharge of synthetic dyes like Rhodamine B (RhB) into aquatic environments poses severe ecological risks due to their toxicity and resistance to natural degradation. Heterogeneous photocatalysis using zinc oxide (ZnO) offers a powerful solution; however, the rapid recombination of photogenerated charges and the challenge of recovering powdered catalysts limit its industrial viability. To address these limitations, this study reports the fabrication of a novel, easily recoverable cellulose/ZnO composite film photocatalyst designed for the efficient degradation of RhB under light irradiation.

The composite film was synthesised via a green solvent method, ensuring the stable immobilisation of ZnO nanoparticles within the hydrophilic cellulose matrix. The structural, morphological, and optical properties of the fabricated cellulose/ZnO composites were characterised using SEM-EDX, FTIR, XRD, and UV-Vis diffuse reflectance spectroscopy.

Photocatalytic assays demonstrated that the cellulose/ZnO composite exhibited significantly higher degradation kinetics for RhB compared to bare ZnO nanoparticles. This enhancement is attributed to the high adsorption capacity of the cellulose network, which creates a highly localised concentration of RhB molecules near the photocatalytic active zones, coupled with the uniform dispersion of ZnO, which maximises active site exposure. Furthermore, the macroscopic nature of the composite allowed for effortless recovery from the reaction medium. The catalyst maintained a degradation efficiency exceeding 87% after 3 consecutive cycles, demonstrating its exceptional stability and potential as a sustainable, closed-loop technology for textile wastewater purification.