Preparation and properties of PVDF hollow fiber membrane for desalination using air gap membrane distillation

The polyvinylidene fluoride (PVDF) hollow fiber membrane was prepared for membrane distillation through thermally induced phase separation (TIPS) using glyceryl triacetate (GTA) and dibutyl sebacate (DBS) as the mixed diluents. The bicontinuous structure of membrane pore was obtained in the case: PVDF/GTA/DBS is 25 wt.%:22.5 wt.%:62.5 wt.%, and the coagulation bath is the water of 20 °C. The membrane porosity and mechanical strength are 0.64 and 2.7 MPa, respectively. The PVDF membrane was characterized using the measurement of the liquid entry pressure (LEPw), scanning electron microscopy (SEM), mean pore, porosity and mechanical strength. The prepared PVDF membrane was tested in an AGMD process for desalination with 7.0 wt.% NaCl solution as the feed. The permeate water flux (JD) and gained output ratio (GOR) simultaneously reach to 5.5 kg/m2h and 6.2. The prepared PVDF membrane can be operated continuously for 240 h without any significant change to JD and GOR, indicating that the prepared PVDF hollow fiber membrane by TIPS method may be of great potential to be utilized in AGMD process for desalination.