Mechanochemical destruction of Chinese PFOS alternative F-53B

As a Chinese specific PFOS alternative used in hard chrome plating industry, F-53B is a single chlorinated polyfluorinated compound which has similar chemical structure as PFOS and shows nearly the same persistent properties. In order to identify its treatability and the influence from its structure, the present study performed mechanochemical destruction of F-53B/F-53 by milling with KOH, during which the destruction efficiency, reaction process, final products and intermediates were investigated. Compared to PFOS, F-53B showed better treatability by milling with KOH while F-53 did not, indicating that the replacement of one fluorine atom by chlorine rather than the introduction of ether bond improves the degradability of the molecule to some extent. Good performances in both F-53B destruction and mineralization were achieved by milling with KOH. During mechanochemical treatment, the destruction of F-53B started from both the chlorine side and the sulfonate side of the molecule. FTIR and XPS analysis show that the organic C-F bonds were cleaved with the generation of formate and inorganic fluoride. The final products of F-53B after milling with KOH were found to be KF, KCI,, K2SO4 and HCOOK, demonstrating mechanochemical treatment to be a promising method for F-53B disposal in aspect of eliminating its persistent, bioaccumulative and toxic properties. The existence of intermediates was also confirmed by the F-19 NMR spectra and classified as short chain degradation fragments of F-53B through LC-MS-MS analysis. Based on the characterizations and analysis, the degradation pathways of F-53B during milling with KOH was also proposed and discussed. (C) 2015 Elsevier B.V. All rights reserved.