Recovery of Perfluoropolyether Surfactants from PVDF and PTFE by Supercritical Carbon Dioxide Extraction

摘要

The extraction of ammonium carboxylate perfluoropolyether surfactants from poly(vinylidenefluorife) (PVDF) and poly(tetrafluoroethylene) (PTFE) was performed with supercritical carbon dioxide. When proper conditions in terms of temperature, pressure and flow rate were used, extraction recoveries higher than 90% were obtained. For PVDF, a very steep increase of efficiency with the pressure in the interval from 9.5 to 12 MPa was observed, up to values higher than 80%. Quantitative recovery were obtained at pressure higher than 20 MPa. A strong influence of the temperature on the extraction recovery was also found In the case of PTFE with a very low content of surfactant (600 ppm), high recovery was obtained at 200 bar, CO2 flow rate 11 g/h, T = 40°C after 240 minutes.