Hematite/selenium disulfide hybrid catalyst for enhanced Fe(III)/Fe(II) redox cycling in advanced oxidation processes

• Published in: Journal of hazardous materials 2022-02, Vol.424 (Pt A), p.127376-127376, Article 127376
• Main Authors: You, Yingying, Huang, Shaobin, Chen, Moshan, Parker, Kimberly M., He, Zhen
• Format: Article
• Language: English
• Subjects: Ferric Compounds; Ferrous Compounds; Hematite; Hydrogen Peroxide; Iron redox cycling; Oxidation-Reduction; Persulfate; Selenium Compounds; Sulfide; Water Pollutants, Chemical - analysis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127376

Regeneration of Fe(II) is a key issue for heterogeneous advanced oxidation processes (AOPs) using iron-based catalysts. Herein, a hybrid catalyst was developed from α-Fe2O3 and SeS2 to enhance the Fe(III)/Fe(II) redox cycling in both hydrogen peroxide (H2O2) system and persulfate (PS) system. The regeneration of Fe(II) was evidenced by the increased Fe(II)/Fe(III) ratio in the used catalyst (205.8% in the H2O2 system or 125.4% in the PS system), compared to 68.4% in the fresh hybrid catalyst Fe/Se-3. Methyl orange was used as a model pollutant to evaluate the degradation performance of the hybrid catalyst. Owing to the promotion of Fe(II) regeneration, Fe/Se-3 achieved a pollutant removal efficiency of 100.0% in 12 min in both systems, significantly higher than that with pure α-Fe2O3 (33.9 ± 3.6% in the H2O2 system or 30.7 ± 2.8% in the PS system). The dominant active species were identified as hydroxyl radicals in the H2O2 system and sulfate radicals in the PS system. In the proposed mechanism, soluble and surface-bound Fe species are provided by α-Fe2O3 to activate H2O2 or PS to radicals, and SeS2 participates in the reactions via Se(IV) reducing Fe(III) to Fe(II) and S atoms being released through protonation to expose more active Se sites. [Display omitted] •A hybrid catalyst Fe/Se-X is successfully synthesized using a facile method.•The hybrid catalyst enhances the degradation performance in both H2O2 and PS AOPs.•Enhancement is related to Fe(III)/Fe(II) redox cycling promoted by the catalyst.•The catalyst is potentially cost-effective due to a low ratio of sulfide to Fe.