Synthesis and characterization of zinc oxide nanoparticles using peppermint tea (Mentha piperita) dregs extract and their photocatalytic performance

Abstract Zinc oxide (ZnO) is a n‐type semiconductor with a wide band gap of 3.37 eV and a large excitation binding energy of 60 meV. ZnO nanoparticles (ZnO NPs) is considered as one of the best photocatalyst for the degradation of pollutants in water since it has large surface area to enhance the photocatalytic activity. This article aims to study the feasibility of using the agricultural waste of peppermint tea dregs extract with zinc nitrate hexahydrate as salt precursor to synthesis ZnO NPs through a simple, low cost, greener and environmentally friendly method. The qualitative phytochemical screening of peppermint tea dregs extract revealed the presence of flavonoids which can be served as the reducing and stabilizing agent in the synthesis of ZnO NPs. Various analytical techniques such as FTIR, UV–vis, XRD, FESEM, EDX and PSA confirmed the presence of ZnO NPs. The photocatalytic performance of the synthesized ZnO NPs showed a 95.03% degradation of crystal violet dye within 4 h of sunlight exposure.