Synthesis, photocatalytic and antibacterial activities of a PDS-activated MgO nanocatalyst: experimental and theoretical studies

Abstract

MgO nanoparticles were successfully synthesized by using an Azadirachta Indica leaf extract and magnesium sulphate dihydrate via a green method followed by calcination of the resulting product of the precursor. The average crystallite size, surface morphology and antibacterial activities of the MgO nanoparticles were discussed. In this work, the average crystallite size was calculated using XRD data and was found to be 18 nm. The band gap energy was measured from UV-vis adsorption and was 4.41 eV. Here, the MgO NPs act as a photocatalyst and PDS was used as an activator for the enhancement of the rate of degradation of Methylene Blue. Degradation was strongly influenced by several factors, such as dosage of PDS, pH, dosage of photocatalyst, temperature, and inorganic salts. Furthermore, Density Function Theory (DFT) calculations were used to provide insights into the degradation of MB dye. The scavenger quenching experiment proved that activated PDS can form SO₄˙⁻ radicals, which control the degradation of MB. The antibacterial activity was determined by a minimum inhibitory concentration technique agar cup method and disc diffusion method. The PDS-activated nanoparticles showed the maximum antibacterial activity towards Klebsiella sp. compared with other bacteria such as E. coli, Mycobacterium sp., and Bacillus sp. We also studied molecular docking, which revealed the strong binding interaction of proteins with the MgO NPs.