Boosting degradation and defluorination efficiencies of PFBS in a vacuum-ultraviolet/S(IV) process with iodide involvement

Perfluorobutane sulfonate (PFBS) is considered to be a promising alternative of perfluorooctane sulfonates (PFOS), while it is also hazardous. The UV/S (IV) system has been confirmed to be effective for PFOS removal from water, while it is inefficient for PFBS decomposition. A hybrid vacuum-ultraviolet (VUV)/S (IV)/KI process was investigated for the degradation of PFBS in aqueous solution. With KI involvement, the degradation rate of PFBS was boosted from 1.8802 mu g h-1 up to 3.5818 mu g h-1 in the VUV/S (IV) process. Alkaline conditions significantly increased the degradation efficiency of PFBS, which can be explained that S (IV) was dominated by SO32- rather than HSO3- and H2SO3 in alkaline conditions. Cl-, HCO3-, NO3-, NO2-, and HA would inhibit the performance of the VUV/S (IV)/KI process via various reactions. In addition, the toxicity of PFBS was significantly reduced by the VUV/S (IV)/KI process. Even in actual waters, the VUV/S (IV)/KI process also presented a satisfying performance in the degradation of PFBS.

Automated summary

Perfluorobutane sulfonate (PFBS) is a potential replacement for perfluorooctane sulfonates (PFOS), but it has also been found to be hazardous. The UV/S (IV) system effectively removes PFOS from water but is inefficient for PFBS decomposition. A hybrid vacuum-ultraviolet (VUV)/S (IV)/KI process was investigated and found to significantly enhance the degradation of PFBS in aqueous solution. The presence of KI and alkaline conditions improved the degradation efficiency, while various ions such as Cl-, HCO3-, NO3-, NO2-, and HA inhibited the process.