Cellulose-Based Hydrogel Decorated with Green Cobalt-Doped CopperOxide Nanoparticles for Photocatalytic Degradation of Methylene BlueDye from Aqueous Solution

Abstract This study investigates the effectiveness of a novel metal oxide-based hydrogel nanocomposite in degrading synthetic dyes in the presence of UV light. The nanocomposite is synthesized through the insertion of metal oxide nanoparticles (NPs) into a hydrogel matrix, optimizing the material's photocatalytic properties. The successful synthesis of the hydrogel nanocomposite was verified using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Through determination of XRD parameters, a successful synthesis of Co-CuO HNCs with an average crystallite size of 10.21 nm was confirmed. SEM images showed that after incorporating spherical-shaped Co-CuO NPs into the hydrogel matrix, the surface of the final composite became rough and fragmented with a surface area of 4.06 m 2 /g. Optical studies showed that the bandgap was reduced as Co-CuO NPs were incorporated into the hydrogel matrix. Photocatalytic degradation experiments were conducted using methylene blue (MB) to assess the hydrogel nanocomposite's efficiency. The results demonstrate a significant enhancement in degradation rates compared to traditional photocatalysts, due to the synergistic effects of the metal NPs and the hydrogel network. Within 120 min, the photocatalytic removal efficiency of MB reached 96% at a pH of 10 using 100 mg of the catalyst. The photocatalytic degradation process followed a pseudo first-order kinetics with a rate constant of 0.0183 min −1 . Moreover, scavenger studies showed that ∙OH radicals were major species responsible for the photocatalytic degradation process. The study highlighted the potential of metal-based hydrogel nanocomposites as efficient and sustainable photocatalysts for environmental remediation, offering a promising solution for the treatment of dye-contaminated wastewater. Future research will focus on optimizing the performance of the nanocomposite and exploring its practical applications in large-scale water treatment processes.