Sustainable environmental-based synthesis of zinc oxide nanoparticles using para rubber leaf extract for photocatalytic degradation of organic pollutants and microbial control in wastewater treatment

Abstract

The use of agricultural waste is an alternative approach to develop zinc oxide nanoparticles (ZnO NPs) without chemical requirements. In this study, ZnO NPs were successfully prepared from agricultural waste, para rubber leaf extract as a capping agent and para wood ash extract as a natural alkaline source, by precipitation method. X-ray diffraction analysis revealed wurtzite hexagonal structure of ZnO NPs. Spherical shape morphology of the biosynthesized ZnO NPs was observed with an average size of 91.60 nm and a bandgap energy of 3.21 eV. Biosynthesized ZnO NPs caused a significant decrease in the numbers of microbial growth, Staphylococcus aureus, Escherichia coli, and Candida albicans, ranging from 90 to 99 % (p < 0.001). Photodegradation efficiency of ZnO NPs under ultraviolet irradiation for 5 h demonstrated the degradation of methylene blue dye, ciprofloxacin, and diuron by 90.6 %, 80.0 %, and 34.8 %, respectively. Similarly, ZnO NPs showed remarkable photocatalytic performance for methylene blue dye degradation up to 99.3 % after 5 h under sunlight. For scavenger test, the results exhibited that hydroxyl radical was the major reactive species responsible for the photocatalytic degradation. ZnO NPs presented good stability and recyclability over five iterations. Biogenic para ZnO NPs have an outstanding potential for degrading organic pollutants and deactivating microorganisms which could be applied for microbial control and photodegradation of organic pollutants.