Thermal defluorination behaviors of PFOS, PFOA and PFBS during regeneration of activated carbon by molten salt

作者：Shen, Zhichao; Zhan, Lu^*; Xu, Zhenming

来源：Frontiers of Environmental Science & Engineering, 2022, 16(8): 103.

DOI：10.1007/s11783-022-1524-9

• PFCs
• Molten sodium hydroxide
• Thermal degradation
• Activated carbon regeneration

Current study proposes a green regeneration method of activated carbon (AC) laden with Perfluorochemicals (PFCs) from the perspective of environmental safety and resource regeneration. The defluorination efficiencies of AC adsorbed perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutanesulfonate (PFBS) using three molten sodium salts and one molten alkali were compared. Results showed that defluorination efficiencies of molten NaOH for the three PFCs were higher than the other three molten sodium salts at lower temperature. At 700 degrees C, the defluorination efficiencies of PFOS and PFBS using molten NaOH reached to 84.2% and 79.2%, respectively, while the defluorination efficiency of PFOA was 35.3%. In addition, the temperature of molten salt, the holding time and the ratio of salt to carbon were directly proportional to the defluorination efficiency. The low defluorination efficiency of PFOA was due to the low thermal stability of PFOA, which made it difficult to be captured by molten salt.The weight loss range of PFOA was 75 degrees C-125 degrees C, which was much lower than PFOS and PFBS (400 degrees C-500 degrees C). From the perspective of gas production, fluorine-containing gases produced from molten NaOH-treated AC were significantly reduced, which means that environmental risks were significantly reduced. After molten NaOH treatment, the regenerated AC had higher adsorption capacity than that of pre-treated AC.

• 单位
  上海交通大学