Visible light assisted Fenton-like degradation of rhodamine B and 4-nitrophenol solutions with a stable poly-hydroxyl-iron/sepiolite catalyst

An efficient heterogeneous catalyst poly-hydroxyl-iron/sepiolite (H-Fe-S) was successfully prepared for photo-assisted Fenton-like reaction by a simple impregnation method. The characterization results (XRD, XPS, BET) of the H-Fe-S catalyst suggested that hydroxyl-iron polycations were present in the sepiolite. The catalytic activity of the H-Fe-S catalyst was evaluated by the degradation, chemical oxygen demand (COD) and total organic carbon (TOC) removal of a xanthene dye rhodamine B (RhB) and a typical persistent organic pollutant 4-nitrophenol (4-NP) in the presence of hydrogen peroxide (H2O2) under visible light irradiation (lambda > 420 nm). The results showed that the H-Fe-S catalyst had good catalytic property for the degradation of both organic contaminants. Fourier transform infrared (FT-IR) analysis of the H-Fe-S catalyst indicated that the catalyst showed good stability for the degradation of RhB even after five recycles. Finally, a possible photocatalytic mechanism was proposed. (C) 2012 Elsevier B.V. All rights reserved.