Photocatalytic degradation of crystal violet dye using phytofabricated zinc oxide nanoparticles from anthocyanin extract

Abstract

This study investigates a coprecipitation method for the production of zinc oxide nanoparticles (ZnO NPs) using anthocyanin (ATH) extract derived from red cabbage (RC) that acts as a reducing, capping and stabilising agent. The efficacy of these NPs in the photocatalytic degradation of crystal violet (CV) dye is assessed thoroughly considering all the relevant influencing parameters such as pH levels, catalytic dosage, and dye concentration, among others. The structural, morphological, surface charge and presence of different functional groups of the synthesized NPs were then analysed using XRD, SEM-EDX, BET, and FTIR. The average particle size of the synthesized ZnO NPs and ZnATH-(O) NPs was 31.12 nm and 27.91 nm, respectively. The BET analysis determined that the surface area of ZnO NPs was 15.685 m²/ g, and that of ZnATH-(O) NPs was 25.187 m²/ g. In contrast to ZnO NPs, ZnATH-(O) NPs exhibit efficient photocatalytic degradation of CV dye. This is due to their improved stability, reduced size, increased surface area and optimized structure. The influence of various parameters like initial dye concentration, catalyst dosage, pH and ionic strength was also assessed under 90 min visible light irradiation. It was observed that ZnATH-(O) NPs show maximum photocatalytic degradation of CV dye in 90 min of visible light irradiation with a degradation efficiency of 96.12 %. This green synthesis method mitigates the environmental consequences associated with conventional chemical synthesis and utilizes the plentiful and renewable resources present in RC, thereby offering a sustainable alternative to a deteriorating environment.