Eco-friendly and Sustainable Biosynthesis of ZnO Nanomaterials for Photocatalytic Degradation of Industrial Effluent under Natural sunlight

This study investigates the synthesis, characterization, and use of Zinc oxide nanoparticles (ZnONPs) for degrading water sample from a common effluent treatment plant (WSCETP) and a specific industrial source (Water Sample from Padmaja Laboratories, abbreviated as WSPL). Zinc oxide nanoparticles were produced through a green microwave-assisted approach with Moringa Oleifera Lam and analysed using various spectroscopic and microscopic techniques. UV-Visible spectroscopy identified a peak at 308 nm and a band gap of 3.06 eV. Fourier Transform Infrared Spectroscopy confirmed Zn-O stretching and various organic groups. X-ray diffraction analysis indicated a hexagonal wurtzite structure with a crystal size of 21 nm, while Field Emission Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy revealed a uniform, spherical morphology, and high purity. Photocatalytic tests showed optimal Chemical Oxygen Demand reductions at 7.5 g/L for Water Sample from Common Effluent Treatment Plant and 10 g/L for Water Sample from Padmaja Laboratories, with pH values of 8.2 and 8.0, respectively. Recyclability tests demonstrated significant activity retention, with Chemical Oxygen Demand reductions of 18% and 62% after four cycles for Water Sample from Common Effluent Treatment Plant and Water Sample from Padmaja Laboratories, respectively. Zinc oxide nanoparticles are effective, recyclable, providing a cost-efficient method for industrial effluent treatment.