High Performing Visible Light Active Ag3PO4/TiO2 Catalyst Anchored on Alumina Beads for Phenol Degradation

Abstract

The study explores the development of visible light active photocatalyst for degradation of organic pollutant such as Phenol. Three different photocatalysts (TiO2, Ag-TiO2 and Ag3PO4/TiO2) were investigated. Sol gel method was used for the synthesis of TiO2 and Ag- TiO2 and in-situ precipitation method for the synthesis of Ag3PO4/TiO2 nanoparticles. The prepared catalysts were immobilized on porous alumina (Al2O3) beads and their comparative performance was evaluated under both UV and visible irradiance for phenol mineralization. The surface area, surface morphology, composition and crystal structure of photocatalysts were characterized using Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The effects of phenol solution pH, catalyst dose, and initial phenol concentration for phenol degradation were investigated and found to be influential. Langmuir, Freundlich, and Redlich-Peterson (RP) isotherms models were used to describe adsorption mechanism and Freundlich and R-P model were found to best fit the adsorption data with lowest chi-squared (χ2) value. Langmuir- Hinshelwood kinetic model best represented the photo-degradation of phenol under both UV and visible light as compared to 1st order and 2nd order kinetic models. The photocatalytic rate constant (KL-H) was significantly greater than the adsorption rate constant (Kads) showing that photocatlysis is the rate determining step. Keywords: Photocatalysis; visible Light; Silver Phosphate; Titania; Phenol Degradation;