Photo-Fenton reaction of supported cationic cyclopentadienyl iron complexes of arene and application as heterogeneous catalysts in photodegradation of dyes under visible light

Cationic cyclopentadienyl iron complexes of arene ([CpFeAr]+) were successfully loaded on silica gel (SiO) by physical absorption. The supported [CpFeAr]+ ([CpFeAr]+/SiO) catalysts were characterized by SEM–EDX, FT-IR and UV–Vis spectra. The catalysts show strong and broad absorptions from 200 to 550 nm. [CpFeAr]+/SiO carries out an effective photo-Fenton reaction with H2O2 under visible light for the photodegradations of organic dyes. Nearly total decolorations of rhodamine B (RhB) and crystal violet (CV) dyes were achieved by using [CpFeAr]+/SiO as the heterogeneous catalyst. Hydroxyl radicals (OH) were found in the photodegradation system of [CpFeAr]+/SiO, H2O2 and dyes under visible light. The negative ΔGel values of CV/[CpFeAr]+ and RhB/[CpFeAr]+ systems indicate that the electron transfer processes for the dye/CpFe+Ar systems are thermodynamically allowed. The possible mechanism for the degradation process of organic dyes in photo-Fenton reaction of [CpFeAr]+/SiO with H2O2 is proposed.