Photo-Fenton oxidation of organic contaminants in wastewater over TiO 2 -ZnO/modified iron-exchanged zeolites: kinetics study and simulation using dispersion-based model

Abstract Organic pollutants present in the wastewater of an oil refinery were oxidized using the advanced photo-Fenton oxidation method with a heterojunction-based photocatalyst consisting of titanium dioxide and zinc oxide nanoparticles deposited on an iron-modified zeolite substrate. The effects of temperature and reaction time on removal efficiency were systematically studied, based on the reduction in chemical oxygen demand, at temperatures ranging from 25 to 60 °C, up to 120 min. A kinetic model was developed to describe the kinetic data of the change in organic content over time at different temperatures. Activation energies were measured for the reaction constants, and the thermodynamic parameters associated with the activation step were evaluated. Subsequently, a dispersion model relied on reaction kinetics, dispersion number, and residence time to simulate the efficiency of different reactors in removing organic contaminants and to compare the performance of ideal and non-ideal flow systems. Simulated results for a dispersion-based model confirmed that an ideal tubular flow reactor has a higher efficiency in breaking down organic pollutants compared to its non-ideal counterpart. Increasing the axial dispersion led to a gradual decline in reactor performance, culminating in the lowest performance, where the lowest conversion rate was observed under fully mixed flow conditions. These results highlight the crucial role of both catalyst design and reactor dynamics in optimizing photocatalytic Fenton systems for the oxidation of organic contaminants in aqueous solutions.