Study on photocatalytic transformation characteristics of PFOA in the presence of structural iron containing clay minerals and iron oxides

• DOI: 10.5194/egusphere-egu25-7586
• Publication Date: 2025-03-14T20:30:02Z
• Authors: Jeongmin Ko; Kyoungphile Nam

Per- and polyfluoroalkyl substances (PFAS), particularly perfluorooctanoic acid (PFOA, C7F15COOH), have been widely used in industry due to their high stability and heat resistance. Their release during manufacturing and treatment processes has led to contamination of aquatic systems and groundwater. While PFOA is generally resistant to degradation under typical aqueous environments, it can be degraded in the presence of catalysts or strong oxidizing / reducing agents. Previous studies have reported that PFOSA derivatives could be transformed into PFOA and shorter-chain PFCAs in the presence of montmorillonite under sunlight irradiation. The Fe3+-containing material mentioned above are widely distributed in natural environments, indicating that the potential for PFOA to undergo photocatalytic degradation facilitated by natural media. This study aims to investigate the potential role for photocatalytic transformation of PFOA using various forms of Fe3+ found in natural environments (structural iron in clay minerals, magnetite, goethite, etc.) under both 254 nm UV light and natural sunlight conditions (including UV radiation of 290-400 nm). When 50 μM PFOA and 500 μM Fe3+-containing montmorillonite were exposed to 254 nm UV light for 3 days at pH 7, a defluorination ratio of 18.2 % was achieved. Future studies will aim to investigate the photocatalytic behavior of structural iron containing clay minerals under natural sunlight irradiation. The photocatalytic reaction between PFOA and nontronite (22.3 wt%), which contains approximately ten times higher structural iron (Fe3+) content than montmorillonite (2.3 wt%) will be investigated. To further understand the potential of PFOA phototransformation under natural conditions, reaction mixtures will be prepared with various forms of naturally occurring Fe3+ media, such as iron oxides to simulate environmental conditions.