Magnetic clay as catalyst applied to organics degradation in a combined adsorption and Fenton-like process

Abstract

In this work, a magnetic sepiolite composite was prepared by chemical co-precipitation method and firstly applied as both adsorbent and catalyst for the removal of bisphenol A (BPA) through a heterogeneous Fenton process. The composite was characterized by XPS, XRD, SEM and TEM techniques. The results of the kinetics study indicate that BPA (50 mg·L−1) can be adsorbed onto the composite via electrons transfer as well as π-π interaction, and then be completely degraded at pH 6.0 within 30 min after the addition of H2O2 (1000 mg·L−1). The analysis of FTIR confirms that the degradation occurred through a combined process of adsorption and oxidation. BPA was pre-concentrated and fixed onto the composite surface and then degraded in-situ by hydroxyl radicals, which were generated through the interaction between H2O2 and surface active sites. To investigate the stability and regeneration properties of the catalyst, the powder composite was extruded into a small cylindrical sample and loaded in a fixed-bed reactor, which was operated under continuous-flow condition. The BPA removal efficiency after 4 h remained at 87%, while the leaching of Fe ions gradually increased. Further, degradation tests in different real waters including tap water and municipal wastewater spiked with BPA (50 μg·L−1) reveal that the influence of real matrix on the oxidation ability was very little. The findings of this study confirm the composite as a promising material for the catalytic removal of organics via the coupled adsorption-oxidation process.