Catalytic degradation of chlorinated organic pollutants over CexFe1−xO2 (x: 0, 0.25, 0.5, 0.75, 1) nanocomposites at mild conditions

Abstract

Oxidation of chlorinated organic pollutants (COPs) like 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), 2,4-dichlorophenoxy acetic acid (2,4-D) using aqueous hydrogen peroxide (30% v/v) over CexFe1−xO2 (x: 0, 0.25, 0.5, 0.75, 1) nanocatalysts was studied. The catalysts were characterised by temperature programmed reduction (H2-TPR) and desorption (NH3-TPD and CO2-TPD) techniques. The reducing power of ceria increased on iron doping as revealed by TPR analysis. CexFe1−xO2 were effective catalysts for Wet Peroxide Oxidation of 4-CP, 2,4-DCP and 2,4-D pollutants. 4-CP (500mg/L) was completely degraded with 37.38% TOC and 58.75% COD removal after 90min at 70°C using Ce0.25Fe0.75O2 catalyst. Complete 2,4-DCP (250mg/L) conversion with 21.60% TOC and 42.44% COD removal was observed at 45min over Ce0.5Fe0.5O2 catalyst at 50°C. 100% catalytic oxidative conversion of 2,4-D (250mg/L) with 23.64% TOC and 45.78% COD removal was achieved at 70°C at 60min. Atomic Absorption Spectrometry (AAS) indicated the extent of leaching of iron from the catalytic structure to be negligible. The mixed oxides were reusable and stable on consecutive uses as indicated by X-ray diffraction (XRD) and surface area measurements. The catalytic efficiency was retained after five successive runs.