Aqueous Photolysis of 6:2 Fluorotelomer Sulfonamide Alkylbetaine

摘要

The aqueous photolytic fate of 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB) was determined experimentally. The PhotoFate system was used to compare the kinetic and mechanistic differences between direct and indirect aqueous photolysis of 6:2 FTAB. Differences attributable to varying aqueous components (nitrate, bicarbonate, and dissolved organic matter (DOM)) were investigated. DOM had a major role in modulating the photolysis rate of 6:2 FTAB, likely by attenuating radical production and quenching radicals in solution. A mechanistic investigation found that the major intermediate of 6:2 FTAB photolysis is 6:2 fluorotelomer sulfonamide (6:2 FTSAm), followed by 6:2 fluorotelomer sulfonate (6:2 FTSA), 6:2 fluorotelomer sulfonamide alkylamine (6:2 FTAA), 6:2 fluorotelomer alcohol (6:2 FTOH) and 6:2 fluorotelomer unsaturated carboxylic acid (6:2 FTUCA). As well, the significant production of perfluoroalkyl carboxylic acids (PFCAs) was observed. A high mass balance (51 to 68 mol % recovery) enabled the proposal of a degradation mechanism for the aqueous photolysis of 6:2 FTAB.