Photo-Fenton remediation of textile wastewater in fluidized-bed reactor using modified laterite: Hydrodynamic study and effect of operating parameters

Abstract

There has been an increased interest for the use of naturally available catalysts in Fenton oxidation procedures. Nevertheless, the potential of laterite soil for the removal of aqueous pollutants via Fenton based technique has not been exhaustively explored. The fluidized bed photo Fenton approach was used in this study to treat textile wastewater with the goal of reducing total organic carbon (TOC) in the wastewater. Thermally modified laterite soil was used as a catalyst in the photo-Fenton process. Severalcharacterizationtechniques including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD) and X-ray photo-electron spectroscopy (XPS), were used to gain insight into the characteristics of a modified laterite catalyst. The application of this catalyst resulted in a significant reduction of total organic carbon (TOC) present in the textile wastewater. Specifically, a TOC reduction of 83% was observed after a reaction period of 100 min, at pH 3, 10 mm of bed height, 30 mM of H2O2 concentration, and a recirculating feed flow rate of 170 ml/min. Kinetic and hydrodynamic investigations were also carried out to have a better understanding of the catalytic processes occurring inside the fluidized-bed reactor. A first-order kinetics could potentially be used to explain the photo-degradation of textile effluent. Up to three successive oxidation cycles, laterite exhibited notable catalytic stability attributed to lesser surface site deactivation. A cost-benefit analysis of the fluidized bed photo-Fenton technique for treating textile effluent was also performed. The fluidized-bed Fenton approach may be a feasible option for treating wastewater containing different colours because of its low operating costs and low environmental effect.