The Photo-Fenton Catalytic Property of the Sulfur-Doped Hematite over Montmorillonite Composite and Its Enhancement

A novel heterogeneous Fenton-catalyst (named S-α-Fe₂O₃/Mnt) was successfully synthesized by doping sulfur into hematite loaded over montmorillonite. The methods of XRD, XPS, EPR and capture test were used to characterize the catalyst for determination of its Fenton catalytic performance and the mechanism of its enhancement. S-α-Fe₂O₃/Mnt had an efficient photo-Fenton catalytic performance with phenol used as a model pollutant in a wide pH range. When pH was 3.0, the Fenton reaction was extremely rapid and 50 mg/L phenol could be 100% degraded in 10 min. When pH was 5.0, the phenol degradation rate was somewhat decreased, but 50 mg/L phenol could be still completely degraded within 60 min. The research results demonstrated that the sulfur doping had made the sulfur ions enter the structure of the α-Fe₂O₃ fraction in S-α-Fe₂O₃/Mnt and this led to a large number of oxygen vacancies formed in the catalyst, which could enhance its photocatalytic performance; on the other hand, the surface acidic sites of montmorillonite could widen the effective pH range of the novel catalyst. Therefore, S-α-Fe₂O₃/Mnt can be a promising heterogeneous Fenton-catalyst for the application in environmental remediation.