Simultaneous adsorption and degradation of 2,4-dichlorophenol on sepiolite-supported bimetallic Fe/Ni nanoparticles

Abstract

A functional sepiolite-supported Fe/Ni (Sep-Fe/Ni) nanocomposite material synthesised through borohydride reduction method was used to degrade 2,4-dichlorophenol (2,4-DCP) from an aqueous solution. 2,4-DCP was completely removed using Sep-Fe/Ni within 120 min, whereas Fe/Ni or sepiolite in isolation yielded removal efficiencies of 90.8% and 8.4%, respectively. As confirmed by scanning electron microscopy and transmission electron microscopy, sepiolite played a role as the supporting material, which distributed Fe/Ni nanoparticles and significantly diminished their aggregation and correspondingly increased reactivity in adsorption and degradation of 2,4-DCP. The presence of Fe0 and Ni0 nanoparticles onto Sep-Fe/Ni was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The optimized contents of Fe and Ni were 5.19 and 0.51 wt%, respectively which resulted in the higher performance of Sep-Fe/Ni catalyst. The key parameters controlling the degradation of 2,4-DCP such as the initial pH of the solution, catalyst amount and reaction time were systematically explored. Furthermore, Sep-Fe/Ni was shown to exhibit promising capability toward removal of total organic carbon. Kinetic analysis revealed that depletion of 2,4-DCP was consistent with a pseudo first-order kinetic model. The possible adsorption and catalytic degradation mechanism were proposed while the degraded products were identified by chromatographic techniques with ultraviolet and mass spectrometry detection. This study showed the promise of Sep-Fe/Ni as a new environmental pollution management candidate for the remediation of water sources contaminated by chlorophenols.