A comparative assessment of Dye degradation by green-synthesised ZnO Nanostructures under solar light irradiation

Recent studies have demonstrated a dramatic escalation in global water consumption, with an approximate 600% increase over the past century. Due to the expansion of the textile industry, there is an increase in the release of synthetic organic dye effluents, which are contributing to the deterioration of water quality, posing significant threats to both human health and aquatic ecosystems. Notably, the textile sector alone utilises approximately 100,000 metric tons of dyes annually, with approximately 15% of these chromophonic compounds being inappropriately discharged into aquatic environments.

Methodology, result, and conclusion: Here, the facile route is applied to synthesise zinc oxide nanoparticles (ZnO NPs) using 80 and 100 ml of aqueous leaf extract of Psidium guajava and Syzygium cumini. The crystalline nature of the synthesised ZnO NPs—80P, 80S, 100P, and 100S—was analysed by XRD; however, Fourier transform spectroscopy and analysis were used to confirm the functional group purity. To examine the photocatalytic activity, 0.1 g/L of synthesised ZnO NPs—80P, 80 S, 100P, and 100B—was immersed in 100 ml of 10 ppm brilliant cresyl green, Malachite green, Eyosin Y, and congored dye solution, stirred for 20 minutes, and kept in the dark to establish an adsorption–desorption equilibrium, followed by exposure to natural sunlight. Moreover, the ZnO NPs 80S and 100S displayed good photocatalytic activity in 140 min of sunlight exposure compared to ZnO NPs 80P and 100P. This study aims to green-synthesise ZnO nanoclusters using two distinct phytochemical reducers and compare their efficiency in solar-assisted photocatalytic degradation of organic dyes in textile wastewater.