Kinetic analysis of 2-chlorophenol photodegradation over alpha-feooh nanoparticles prepared in cationic surfactant electrolyte

Abstract

2-Chlorophenol (2-CP) which widely used in various chemical processes such as in agriculture, paper, cosmetic, biocide, and public health industries, presents serious threats to the surrounding ecosystem. In recent years, photocatalytic treatment system was found to be the most promising alternative for the abatement of this recalcitrant pollutant1. a–FeOOH as a semiconductor catalyst, has been widely used in the degradation of many chlorinated compounds due to its unique electrical, optical and photoluminescence properties2. Owing to the advantages of using electrochemical as a catalyst preparation method3, this study reports the electrosynthesis of a– FeOOH nanoparticles in a cationic surfactant, IS (IS-FeOOH). IS that acts as an only electrolyte is capable in producing IS-FeOOH nanoparticles without any agglomeration4. Its crystallinity and morphology were analyzed using an X–ray diffractometer and a transmission electron microscope, respectively. The characterization results verified that IS plays an important role in the miniaturization of the a–FeOOH nanoparticles, with a diameter range of 5–10 nm (Figure 1). The activity of IS–FeOOH was tested on a photodegradation of 2– chlorophenol (2–CP). Results showed that at nearly neutral condition of pH 5 was able to completely degrade 2–CP within 180 min of reaction at 50°C, using 0.03 g L-1 of catalyst dosage and 50 mg L-1 of 2–CP initial concentration. Kinetic analysis indicates that the apparent rate constant, kapp increased with increasing initial concentration of 2–CP up to 50 mg L-1 and then reduced as the initial concentration increased to 70 mg L-1. The calculated kr and KLH were 8.3 mg L–1 min–1 and 2.8 × 10-4 L mg–1, respectively, suggesting a surface reaction was the controlling step of the process. The results provide strong evidence to support the potential use of IS as an alternative electrolyte to synthesize nanosized photocatalyst that can be used to treat organic pollutants.