Rapid Water Disinfection Using ZnO Nanoparticles Synthesized from Citrus aurantifolia

Water is the most basic asset required for survival. Presently, most of the water resources are contaminated with pathogens. As the use of safe water which is clean and pathogen-free is the hour of need, nanotechnology can provide a noticeable improvement to the water disinfection process. The present study aims to synthesize multifunctional ZnO nanoparticles using Citrus aurantifolia peel extract at low temperature, taking care that all the bioactive phytochemicals of the peel were retained. SEM image showed the spherical ZnO nanoparticles size was found to be less than 100 nm. XRD confirmed the wurtzite hexagonal ZnO structure by showing peaks at 2 θ value of 31.74° and 36.17°. FTIR results showed relative peaks for green synthesized ZnO at 452.60 cm −1 and also showed the presence of a high level of phytochemical constituents. UV spectroscopy confirmed the presence of ZnO in the extract by a strong peak at 345 nm. Evaluation of the antimicrobial activity of ZnO nanoparticles against various waterborne pathogens was done. Results indicate that ZnO nanoparticles could potentially be strong antimicrobial reagents to reduce waterborne pathogens. Finally, the feasibility of using ZnO nanoparticles as water disinfectant for water collected from RR Nagar Lake and BGS Lake, Bengaluru, was investigated. Cell count per mL reduced to 50 CFU/mL from 18,500 CFU/mL in RR Nagar lake water and 1 CFU/mL from 70,000 CFU/mL in BGS lake water, Bengaluru. A total viable count showed 99.7% and 99.9% reduction in micro-organisms in RR Nagar and BGS Lake water, respectively.