A novel β-FeOOH/NiO composite material as a potential catalyst for catalytic ozonation degradation of 4-chlorophenol

Abstract

In this study we report on the organic linker mediated fabrication and catalytic activity of a novel β-FeOOH/NiO composite material for the first time. Four-chlorophenol (4-CP) was used as a target molecule to evaluate the catalytic activity of the composite material in ozonation reactions. Three different β-FeOOH loadings, labelled 2, 5 and 10% β-FeOOH/NiO composites were prepared. The 5% β-FeOOH/NiO composite material showed the highest activity in the composite structure. XRD, FTIR and TEM were used to characterise the composite structure. Evidence of a chemically bonded interface between β-FeOOH and NiO was apparent from the FTIR and TEM results. Adsorption of 4-CP on the catalyst surface was found to be negligible. First order reaction kinetics were used to describe the 4-CP degradation behaviour and the rate constants increased with increasing initial pH of the solution. No detectable amount of both Fe and Ni leaching into the solution was observed at a pH range of 10–2.3. After 20 min of the ozonation reaction, 85% of 4-CP was removed by the heterogeneous system as opposed to 47% by ozonation alone. The developed composite material exhibited good recyclability as the catalytic activity of the material could be recovered by calcination after use. A maximum of 66% of COD was removed just after 50 min of the catalytic ozonation reaction. The enhanced catalytic activity of the composite material was due to higher generation of OH˙ which was supported by photoluminescence (PL) experiments.