Taguchi optimization of COD removal by heterogeneous Fenton process using copper ferro spinel catalyst in a fixed bed reactor-RTD, kinetic and thermodynamic study

In this study, copper ferrite (CuFe2O4) catalyst was synthesized by co-precipitation method and oxidation of organic matter present in pulp and paper effluent was investigated in laboratory scale. The Taguchi optimization method was employed using an orthogonal array with five levels for the experimental design in the fixed bed reactor. Influence of process variables such as pH, concentration of H2O2, bed height and reaction time was optimized for the chemical oxygen demand (COD) removal by analysing statistical parameters. After 2 h of reaction time, about 78% COD removal was achieved with optimized parameters. COD removal from wastewater followed first order kinetics with rate constant 0.014 min(-1) . A thermodynamic study was carried out to find the properties like enthalpy, entropy and Gibbs free energy. It gave Delta H and Delta S as 21.984KJ mol(-1) and -208.071KJ mol(-1) K-1 . Catalyst reusability and stability was checked by regenerated catalyst. The catalyst showed good reusability for four consecutive runs and amount of Fe and Cu in treating effluent was found to be below discharge limit which was tested by atomic absorption Spectroscopy (AAS).