Self-assembling of 3D layered flower architecture of BiOI modified MgCr2O4 nanosphere for wider spectrum visible-light photocatalytic degradation of rhodamine B and malachite green: Mechanism, pathway, reactive sites and toxicity prediction

In this study, 3D BiOI nanoparticle (BOI NPs) modified MgCr2O4 nanoparticle (MCO NPs) was fabricated by simple sonochemical and coprecipitation method for the enhanced photocatalytic activity. The morphological structure of the MgCr2O4-BiOI nanocomposite (MCO-BOI NCs) was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS), electron impedance spectroscopy (EIS) and photo luminescence (PL). The lower in the PL intensity and small arc in EIS for NCs shows the effective charge separation and lower in rate of recombination of charge carriers in NCs than the pure MCO and BOI NPs. The degradation efficiency of Rhodamine B (RhB) and malachite green (MG) by MCO-BOI NCs was found to be 99.5% and 98.2% receptivity. In addition, the photocatalytic degradation of RhB and MG was studied under various environmental parameters (different pH, varying the concentration of NCs and dyes) and response surface (RSM) plot was performed. The complete mineralization of RhB and MG by MCO-BOI NCs was determined by TOC. In addition, the photocatalytic degradation pathway was elucidated based on GC-MS results and Fukui function. In addition, the toxicity of intermediate formed during the degradation of RhB and MG was predicted by ECOSAR. The present work highlights the application of MCO-BOI NCs in environmental remediation for toxic pollutant removal.