Chitosan/Hydroxyethyl Cellulose Gel Immobilized Polyaniline/CuO/ZnO Adsorptive-Photocatalytic Hybrid Nanocomposite for Congo Red Removal

Advanced photocatalytic degradation based on polymer/metal oxide hybrid composites can convert organic and related pollutants into an environmentally benign product. In this study, chitosan/hydroxyethyl cellulose (CS/HEC) gel immobilized polyaniline (PANI)/CuO/ZnO composite was prepared by in situ oxidative polymerization followed by ex-situ dispersion. The hybrid nanocomposite synthesized was characterized by FESEM, FTIR, EDX, XRD, TGA, and UV-Visible absorption spectroscopy. The degradation study was performed in the optimum time, pH, PANI/CuO/ZnO loading on CS/HEC gel, and catalyst dosage using 100 mu M Congo red. The correlation coefficients (R-2) of pseudo-second-order adsorption kinetics were higher than 0.98 at different temperatures, signifying that the model was well fitted and the chemical interaction between Congo red and the catalyst at the interface. The activation energy of 19.56 kJ/mol showed chemisorption of Congo red at the interface. The negative values of standard Gibbs free energy demonstrated that the Congo red adsorbed spontaneously to the catalyst surface. According to the Langmuir-Hinshelwood kinetics model, Congo red photocatalytic degradation followed pseudo-first-order kinetics. The decrease in degradation efficiency with the addition of ammonium oxalate and isopropyl alcohol proved that both positively charged holes and hydroxyl radicals were involved in the catalysis. The catalytic degradation efficiency of the 0.4 g/L catalysts was 99.8 and 93.7% in the 1st and 4th cycle, respectively, indicating that it is efficient, stable, and recyclable. The resulting hybrid nanocomposite is a promising photocatalyst for removing anionic dyes.