Polyaniline/cupric oxide organometallic nanocomposites as a sonocatalyst for the degradation of methylene blue: Experimental study, RSM optimization, and DFT analysis

In this study, an organometallic nanocomposite consisting of polyaniline (PANI) and copper oxide (CuO) was synthesized using the in-situ polymerization method of aniline, with copper chloride serving as a polymerization catalyst and precursor, along with sodium hydroxide to synthesize CuO nanoparticles. Various techniques were employed to characterize the synthesized nanocomposite, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), and determination of pH of the point of zero charge (pH_pzc). The catalytic performance of the PANI/CuO nanocomposite was evaluated for the degradation of methylene blue (MB), both with and without ultrasonic irradiation. The nanocomposite catalyst exhibited significantly improved catalytic efficiency for MB degradation in ultrasonic irradiation, compared to degradation without ultrasonic irradiation. The experimental conditions were optimized using the Box-Behnken Design (BBD), resulting in finding that the highest MB degradation efficiency reached 95% under ultrasonic irradiation and 74% without it. These results were achieved with a dye concentration of 50 mg/L, a catalyst dose of 0.4 mg/L, and a contact time of 60 minutes. Theoretical calculations suggest that BM molecules promote an attacking mode owing to their electrophilic characteristics, which make them more likely to accept electrons. This propensity leads to the formation of an antibonding orbital in conjunction with PAN/CuO, indicating a synergistic effect between organic molecules (PANI) and inorganic nanoparticles (CuO). This synergistic effect enhances the catalytic activity. Furthermore, the catalyst has demonstrated excellent reusability and stability, suggesting its potential application as an efficient PANI/CuO nanocomposite catalyst for the removal of organic pollutants.