A Novel β-CD−Hemin Complex Photocatalyst for Efficient Degradation of Organic Pollutants at Neutral pHs under Visible Irradiation

A novel photooxidative system for degrading toxic organic pollutants, including organic dyes and small molecular compounds such as Rhodamine B (RhB) and 2,4-dichlorophenol (DCP), is reported. A metal−organic complex (β-cyclodextrin−hemin, CDH), synthesized by combining β-CD with the bioactive small molecule hemin, can efficiently activate hydrogen peroxide to oxidize and mineralize the target compounds in aqueous media at neutral pHs under ambient conditions of temperature and pressure and with visible light irradiation (λ > 450 nm). The RhB and DCP were mineralized at yields of 72% and 85% at ratios of catalyst to substrate of 1:200 and 1:1000, respectively. Meanwhile, the catalyst exhibited excellent stability. The photoreaction processes were examined by UV/vis spectroscopy, high-performance liquid chromatography, ion chromatography, IR, spin-trapping electron paramagnetic resonance, and total organic carbon measurements. A possible photooxidative mechanism for the degradation of organic pollutants in aqueous CDH/H 2 O 2 solutions under visible light illumination is proposed on the basis of the experimental results.