Efficient photocatalytic degradation of methyl orange and malachite green by Ag3PO4 decorated BiOBr nanoflower under visible light: Performance evaluation, mechanism insights and toxicology of the by-products

Abstract

The development of an efficient and robust photocatalyst is of great importance for the effective treatment of toxic pollutants. In this study, novel Ag 3 PO 4 microspheres were decorated on the nanorod embedded flower-like BiOBr designed for the effective photodegradation of methyl orange (MO) and malachite green (MG) dyes. The synthesized particle was characterized to understand the structural and morphological features using HR-TEM, XRD, SEM, PL, ESR, FT-IR, XPS, EIS and N 2 adsorption and desorption. The degradation rate constants for MG (0.0132 min −1 ) were 3.47 and 3.14 times greater than BiOBr and Ag 3 PO 4 . Similarly, the rate constants for MO degradation (0.0151 min −1 ) are 3.87 and 3.97 times greater than BiOBr and Ag 3 PO 4 . The effect of initial MG and MO dye concentration, reaction pH, nanocomposite (NC) concentration was investigated. The NC exhibited excellent visible light photodegradation of 99.8% for MO and 93.4% for MG dyes at 180 min and 200 min respectively. A S-scheme heterojunction were proposed as the possible mechanism for the photodegradation of the dyes. The prepared photocatalyst exhibits excellent structural stability and reusability. The toxicity of the intermediates were predicted by the ecotoxicity analysis using ECOSAR software where the end products were less toxic than parent MG and MO. The degradation pathway were elucidated to predict the possible intermediates and to confirm the complete mineralization of the compound using GC-MS analysis. The proposed study can be implemented for practical application for the degradation of organic pollutants present in the water bodies. • Ag 3 PO 4 microspheres were decorated on the flower-like BiOBr. • BiOBr/30%Ag 3 PO 4 exhibited superior photodegradation of MO and MG dyes. • BiOBr/Ag 3 PO 4 shown excellent stability and recyclable properties. • Heterojunction of semiconductor accelerated separation of photoelectron-hole pairs.