Unveiling nano-empowered catalytic mechanisms for PFAS sensing, removal and destruction in water

Per- and polyfluoroalkyl substances (PFAS) are organofluorine compounds used to manufacture various industrial and consumer goods. Due to their excellent physical and thermal stability ascribed to the strong CF bond, these are ubiquitously present globally and difficult to remediate. Extensive toxicological and epidemiological studies have confirmed these substances to cause adverse health effects. With the increasing literature on the environmental impact of PFAS, the regulations and research have also expanded. Researchers worldwide are working on the detection and remediation of PFAS. Many methods have been developed for their sensing, removal, and destruction. Amongst these methods, nanotechnology has emerged as a sustainable and affordable solution due to its tunable surface properties, high sorption capacities, and excellent reactivities. This review comprehensively discusses the recently developed nanoengineered materials used for detecting, sequestering, and destroying PFAS from aqueous matrices. Innovative designs of nanocomposites and their efficiency for the sensing, removal, and degradation of these persistent pollutants are reviewed, and key insights are analyzed. The mechanistic details and evidence available to support the cleavage of the CF bond during the treatment of PFAS in water are critically examined. Moreover, it highlights the challenges during PFAS quantification and analysis, including the analysis of intermediates in transitioning nanotechnologies from the laboratory to the field.

Highly efficient and stable Zr-doped nanocrystalline PbO2 electrode for mineralization of perfluorooctanoic acid in a sequential treatment system

Zr-doped nanocrystalline PbO₂ (Zr-PbO₂) film electrodes were prepared at different bath temperatures. The Zr-PbO₂ electrode doped at 75°C (75-Zr-PbO₂) featured high oxygen evolution overpotential, large effective area and good electrocatalytic performance. The oxygen evolution potential and the effective area of 75-Zr-PbO₂ achieved 1.91V (vs. SCE) and 9.1cm², respectively. The removal efficiency and the defluorination ratio of PFOA reached 97.0% and 88.1% after 90min electrolysis. The primary mineralization products (i.e., F^- and intermediates) and their change trends were determined. The 75-Zr-PbO₂ electrode was introduced to sequentially treat the PFOA wastewater. In an 116h of 75-Zr-PbO₂ electrocatalysis sequential process, the PFOA, PFHpA, PFHxA, PFPeA, PFBA, PFPrA, TFA, and TOC concentrations were reduced to below 30, 2.5, 1.3, 1.0, 0.5, 0.2, 0.1, and 9mgL^-1, respectively, demonstrating the promising application of the sequential treatment system for the treatment of PFOA wastewater.