Green synthesis of ZnO: Effect of plant concentration on the morphology, optical properties and photodegradation of dyes and antibiotics in wastewater

Abstract

Commelina beghalensis (C. benghalensis)-mediated zinc oxide nanoparticles (NPs) were successfully synthesised. The effect of C. benghalensis plant extract concentration on the morphology, optical and photodegradation efficiency was investigated. These materials were characterised using SEM, XRD, UV–vis, FTIR, TGA, BET, EPR, PL and VSM. XRD and UV–vis confirmed the formation of these materials. According to XRD measurements, the green-synthesised nanoparticles have a hexagonal wurtzite structure. SEM displayed various morphologies from platelets-flaky to spherical spheres. Ferromagnetism features were concentration-dependent since the material synthesised using 30 g of the extract was highly magnetic. This behaviour was also supported by the EPR and PL analyses which confirmed the formation of a higher concentration of oxygen vacancies. Furthermore, the lowest bandgap energy of 3.4 eV and the smallest particle sizes (28 nm) were also achieved using the most concentrated extract. The photocatalytic properties of the prepared materials were tested against methylene blue dye (MB) and sulfisoxazole (SSX). The highest degradation was achieved at 81% for MB using the highest concentrated material. Trapping studies showed that hydroxyl radicals were the major species responsible for the degradation of MB. From this analysis, it can be noted that the effect of plant concentration did play a role on the morphology and degradation of various pollutants. Lastly, these environmentally safe materials can be used for the degradation of various pollutants.