Enhanced removal of perfluorooctanoic acid with sequential photocatalysis and fungal treatment

• Published in: Environmental science and pollution research international 2023-08, Vol.30 (39), p.91478-91486
• Main Authors: Khan, Mohd Faheem, Paul Guin, Jhimli, Thampi, Ravindranathan K., Sullivan, James A., Murphy, Cormac D.
• Format: Article
• Language: English
• Subjects: Acids; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biocatalysts; Biodegradation; Biodegradation, Environmental; Bismuth; Caprylates; Carboxylic Acids; Combined treatment; Contaminants; Cytochrome P450; Cytochromes P450; Defluorination; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fluorocarbons; Fungi; Humans; Perfluoro compounds; Perfluoroalkyl & polyfluoroalkyl substances; Perfluorooctanoic acid; Photocatalysis; Photocatalysts; Photodegradation; Short Research and Discussion; Short Research and Discussion Article; Substrates; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 1614-7499; 0944-1344; 1614-7499
• DOI: 10.1007/s11356-023-28588-5

In this paper, we report the degradation of perfluorooctanoic acid (PFOA), which is a persistent contaminant in the environment that can severely impact human health, by exposing it to a photocatalyst, bismuth oxyiodide (BiOI), containing both Bi 4 O 5 I 2 and Bi 5 O 7 I phases and a fungal biocatalyst ( Cunninghamella elegans ). Individually, the photocatalyst (after 3 h) and biocatalyst (after 48 h) degraded 35–40% of 100 ppm PFOA with 20–30% defluorination. There was a marked improvement in the degree of degradation (90%) and defluorination (60%) when PFOA was first photocatalytically treated, then exposed to the fungus. GC- and LC–MS analysis identified the products formed by the different treatments. Photocatalytic degradation of PFOA yielded short-chain perfluorocarboxylic acids, whereas fungal degradation yielded mainly 5:3 fluorotelomer carboxylic acid, which is a known inhibitor of cytochrome P450-catalysed degradation of PFAS in C. elegans . The combined treatment likely resulted in greater degradation because photocatalysis reduced the PFOA concentration without generating the inhibitory 5:3 fluorotelomer carboxylic acid, enabling the fungus to remove most of the remaining substrate. In addition, new fluorometabolites were identified that shed light on the initial catabolic steps involved in PFOA biodegradation.