Ionic Liquid Assisted Synthesis of Metal Oxide Nanoparticles and Their Application for Photocatalytic Dye Degradation on Malachite Green

Abstract

Organic dyes are extensively used in numerous sectors, for example, textiles, leather, food, pharmaceuticals, paint, and plastic. Industries have contributed directly to significant environmental contamination, particularly in the form of water pollution. The present work comprises a comparative study of the photocatalytic degradation of malachite green (MG) dye by using metal oxide nanoparticles (MONPs) such as copper oxide nanoparticles (CuO NPs), zinc oxide nanoparticles (ZnO NPs), and iron oxide nanoparticles (Fe₃O₄ NPs) coated with 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF₆] ionic liquid (IL) and bare MONPs. The above-mentioned nanoparticles (NPs) were prepared by using the co-precipitation method. The physico-chemical characteristics of the bare MONPs and IL-coated MONPs were characterized by X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), UV–visible absorption spectroscopy (UV–Vis), photoluminescence (PL), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). Average crystallite sizes of IL-coated CuO NPs (13.9 nm), ZnO NPs (28.02 nm), and Fe₃O₄ NPs (4.16 nm) were found from an XRD study. The band gap values of [BMIM][PF₆] coated CuO, ZnO, and Fe₃O₄ NPs were computed to be 1.85, 2.06, and 1.56 eV, respectively. The photocatalytic efficacy of synthesized NPs was examined on MG dye during a 60-min period. The photocatalytic degradation of MG dye was more effective when using MONPs with an IL coating compared with MONPs without an IL coating.