Mineralization and deflourization of 2,2,3,3-tetrafluoro-1-propanol (TFP) by UV/persulfate oxidation and sequential adsorption

This work demonstrates the combination of UV/persulfate and adsorption processes for treating 2,2,3,3-tetrafluoro-1-propanol (TFP) wastewater. Under the optimum conditions, 20mM persulfate (S2O82-), 254nm UV-C, and pH 3, 99.7% of TOC removal from an initial TFP solution of 1.39mM was achieved. The photolysis of persulfate (S2O82-) by UV irradiation yielded the sulfate radical (SO4-) with high activity, which mineralized most of the TFP in 2h. The released fluoride ions were then removed by using a waste iron oxide, BT-4 adsorbent. 20gL^-1 BT-4 adsorbed 95% of the fluoride that was produced by mineralization of 1.39mM TFP. The kinetics and isotherms of adsorption were examined to determine the fluoride removal efficiency of BT-4 which co-existed with the sulfate ions from the consumed sulfate radicals. Accordingly, the kinetics of adsorption was described by a pseudo-second-order rate model, while the adsorption isotherms were well fitted with the Langmuir model. BT-4 had a high adsorption capacity of 26.4mgg^-1 (25°C) in removing the fluoride from TFP mineralization, suggesting that the co-existing sulfate ions never significantly affected the fluoride removal efficiency.