Preparation Of PVDF/PPESK Alloy Membranes And Application

Membrane distillation (MD), which has been applied to seawater desalination, water purification and thermally labile substances concentration, is an innovative membrane separation technique. The polyvinylidenefluoride (PVDF) is an ideal membrane material for its hydrophobicity, thermal stability, dissolubility and easy preparation than polytetrafluoroethylene (PTFE) and polypropylene (PP). But the hollow fiber membrane made from PVDF had low mechanical intension and small pore size. Furthermore, the PVDF membrane shrinken significant after dried. In this study, the PVDF and PPESK were mixed in the dope solution, to get large size, high porosity membrane and at the same time high hydrophobic membranes.Hollow fiber alloy membranes have been made from a dope solution containing polyvinylidenefluorid (PVDF)/poly (phthalazinone ether sulfone ketone) (PPESK) /N-methly-2-pyrrolidone (NMP) /additive by using a dry-jet wet spinning process. Polyethylene (PEG) and LiNO3 were selected as the mix additive and the water was the jellies The performance of hollow fiber alloy membrane in vacuum membrane distillation was investigated with 5000 ppm sodium chloride aqueous solution as feed solution. The results showed that 9:0.5 and 9:1 were better ratio for PVDF and PPESK. The permeate flux of alloy membrane was 10.70 L m~-2h~-1 and the permeate flux of the membrane made from PVDF was 1.42 L m~-2h~-1 at 0.01MPa. The rejections of two membrane had little difference. At the same time, the alloy membrane had better mechanical performance than that of the PVDF membrane.The treatment of chlorophenol solution was also been applied using vacuum membrane distillation. The mass transfer coefficient was calculate and the relationship between temperature, pressure and initial concentration of the feed was investigated.