Water treatment plant sludge as iron source to catalyze a heterogeneous photo-Fenton reaction

In this work, water treatment plant sludge (WTP) was employed as an alternative heterogeneous photo-Fenton catalyst towards amaranth dye removal from aqueous solution. WTP sludge was calcined at 600 degrees C and posteriorly characterized by X-ray fluorescence (XRF), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), N-2 adsorption/desorption isotherms and scanning electron microscopy (SEM). The results indicated that the material was composed by 12.6 wt% of Fe2O3, and has mesoporous structure, with an average pore diameter of 13.2 mm, pore volume of 0.2 cm(3) g(--1), and specific surface area of 60 m(2) g(--1). The optimum experimental conditions for the photo-Fenton reaction were determined by a central composite rotational design (CCRD) coupled with response surface methodology (RSM). A decolorization efficiency of 97% was achieved at pH = 2.8, concentration of H2O2 = 5.5 mmol L--1, and catalyst mass of 0.75 g L--1. These results indicated that the calcined sludge has potential to be employed as an alternative catalyst in photo-Fenton reaction to degrade organic molecules present in liquid effluents. (C) 2019 Elsevier B.V. All rights reserved.