Accelerating of Fe3+/Fe2+ redox cycle using palygorskite as phase regulator for peroxymonosulfate oxidation

Abstract

This study presents the synthesis of a Fe-based catalyst via a one-pot calcination method, emphasizing the role of palygorskite (Pal) in modifying the catalyst's phase composition. The incorporation of palygorskite led to a robust interaction with FeOCl and FeCl₂, resulting in a porous structure enriched with active sites. The prepared catalyst had high surface area (69.1 m²/g) and pore volume (0.167 cm³/g) with interwoven rod-like structure. These characteristics were essential for enhancing the activation of peroxymonosulfate (PMS). Textile wastewater is one of the main sources of industrial wastewater in China, and RhB is one of the commonly used dyes in textile industry. The performance of the synthesized Fe/Pal catalyst was evaluated in the context of degrading Rhodamine B (RhB). The catalyst exhibited remarkable efficacy attributed to the dynamic Fe³⁺/Fe²⁺ redox cycle. Under optimized conditions, 0.1 g/L activated catalyst can remove 85 % RhB within 10 min. Quenching experiments further elucidated the mechanisms involved in pollutant removal, revealing that sulfate radicals and singlet oxygen were the predominant reactive species. Overall, the findings underscored the potential of iron/mineral matrix composite catalysts in the effective treatment of organic pollutants. This research not only advances the understanding of catalyst design but also offers promising pathways for the broader application of these materials in environmental remediation efforts.