Fe(bpy)32+ supported on amidoximated PAN fiber as effective catalyst for the photodegradation of organic dye under visible light irradiation

A novel heterogeneous Fenton photocatalyst was prepared by supporting Fe(bpy)32+ onto amidoximated polyacrylonitrile (PAN) fiber and then used for the degradation of organic dye under visible irradiation. FTIR, XPS and UV–vis diffuse reflectance spectroscopy analyses suggest that the Fe(bpy)32+ molecules were distorted during their immobilization onto the fiber support, and the OH groups in amidoxime group had interacted with Fe(bpy)32+. Upon visible light irradiation, the catalyst was found to be highly effective for the degradation and mineralization of Rhodamine B at a neutral pH and could be easily recycled without any loss of activity. The interaction of OH groups with Fe(bpy)32+ groups was considered to be responsible for the high catalytic performance since the Fe(bpy)32+ supported on unmodified PAN fiber did not show any photoactivity. The OH groups in conjunction with 2,2′-bipyridine ligands may provide a flexible bifunctional coordination environment for iron (II/III) ions. ESR studies indicate that hydroxyl radicals are involved in this photocatalysis process, and a possible mechanism is proposed.