【Frontiers in HaiChuan Chemical Technology】Microdroplet chemistry strategies can effectively remove perfluorinated compounds from water

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Recently, a team led by researcher Wang Feng and associate researcher Jia Xiuquan from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, in collaboration with a team led by Jiang Guibin, an academician of the Chinese Academy of Sciences and researcher at the Research Center for Ecology and Environment, utilized the triboelectric effect that occurs at the gas-liquid-solid interface of microdroplets to develop a new strategy for efficiently mineralizing perfluorooctanoic acid (PFAS) under mild conditions in aqueous media, thereby effectively preventing the formation of secondary pollutants. Due to their characteristics of being difficult to degrade, capable of migrating over long distances, prone to bioaccumulation, and posing potential health risks, perfluorinated compounds have become a key focus and challenge in China’s efforts to combat pollution. Existing PFAS degradation technologies usually require operation under harsh conditions, and they have limitations such as incomplete degradation (low mineralization rate) and the formation of short-chain PFAS by-products. Previously, the team used ultrasound to drive rapid conversion of water between microdroplets, water vapor, and the bulk phase, thereby creating \"artificial clouds\" with an alternating voltage. Based on this, the study introduced calcium silicate into \"artificial clouds\" and utilized the electrochemical reaction at the gas-liquid-solid three-phase interface induced by microdroplets to achieve efficient mineralization of perfluorooctanoic acid and fixation of fluoride ions. Through theoretical calculations combined with high-resolution mass spectrometry analysis, the researchers confirmed that the hydrated electrons and radicals generated at the microdroplet interface can cause deep defluorination and hydrogenation of perfluoroalkyl chains; this defluorination and hydrogenation process occurs prior to the cleavage of C-C bonds in these chains, thereby suppressing the formation of short-chain PFAS. The results showed that after 6 hours of reaction, perfluorooctanoic acid was nearly completely mineralized, with a carbon yield of over 98% and a fluoride ion removal rate of greater than 96%. After continuing the reaction for another 24 hours, the concentration of perfluorocarboxylic acids in the water reached the latest requirements set by the U.S. Environmental Protection Agency and the EU’s Drinking Water Directive regarding PFAS concentrations in drinking water. This study confirms the ability of microdroplet interfaces to efficiently degrade PFAS, providing a new strategy for dealing with these emerging pollutants and enhancing the academic community’s understanding of the migration and natural degradation mechanisms of persistent organic pollutants at the sea-air interface.