Decolorization of Direct Black 22 by Photo Fenton like Method Using UV Light and Zeolite Modified Zinc Ferrite: Kinetics and Thermodynamics

Abstract

In this study, a heterogeneous catalyst was prepared to enhance photo-Fenton like oxidation of Direct Black-22 (DB-22). Zeolite modified with zinc ferrite was used as a catalyst. The prepared catalyst was characterized using FTIR, SEM, EDS and XRD. The effect of various parameters like catalyst modification with HCl, H₂O₂ amount, catalyst amount, CaCl₂ amount, initial pH, initial concentration and temperature on the decolorization of DB-22 was studied under UV light. Kinetic and thermodynamic properties were investigated. The highest decolorization of DB-22 was found to be 93.3% under the following conditions: initial concentration: 0.070 g/L, initial temperature: 25 °C, original pH, H₂O₂ amount: 2.78 g/L, m-ZZF amount: 3 g/L, CaCl₂ amount: 3.75 g/L, reaction time: 60 min and UV light. The activation energy was found to be -14.76 kJ/mol under the studied conditions. The decolorization reaction was an exothermic reaction, and the calculated reaction enthalpy was -17.31 kJ/mol. The activation entropy was calculated to be -0.326 kJ/mol. The standard Gibbs free energy change of the activation had a positive value, and it increased with increasing temperature.