Preparation And Application Of Crosslinked PDMS/PVDF Hydrophobic Microporous Membranes

A hydrophobic microporous membrane with semi-interpenetrating polymer network(semi-IPN) based on polydimethylsiloxane(PDMS) and polyvinylidenefluoride(PVDF) was fabricated by non-solvent induced phase separation(NIPS) process. Membrane structure and performance can be tuned by varying the mass ratio of PDMS/TEOS and PDMS/PVDF, respectively. All semi-IPNs PDMS-PVDF hydrophobic microporous membranes were characterised by scanning electron microscopy(SEM), attenuated total reflection Fourier transform infrared(ATR-FTIR) spectroscopy, thermogravimetric analysis(TGA), X-ray diffraction(XRD) and water contact angle(WCA) etc. The results showed that with the increase of dosage of TEOS, the thermal stability and mechanical properties of membrane increased; the pore size distribution became narrow. In addition, with the increase of mass ratio of PDMS/PVDF, the thermal stability and mechanical properties of membrane increased first and then decreased; pore size distribution in mass ratio of PDMS/PVDF of 1:3, a bimodal pore distribution was generated.Furthermore, an application to use the prepared PDMS/PVDF hydrophobic microporous membrane to desalt through VMD was carried out. The results showed that the highest flux of 21.52 kg/(m2·h) can be obtained for the membrane with the mass ratio of PDMS/PVDF of 1:30 and PDMS/TEOS of 3:1 at the feed(30 g/L NaCl solution) temperature of 80 oC, the vacuum degree of 77 kPa and the feed liquid velocity of 80 L/h. In addition, the high salt rejection of 99.9% can be obtained for all of resulting membranes in VMD.At last, another application for the prepared PDMS/PVDF hydrophobic microporous membrane was the separation of oil-water emulsion in ultrafiltration process. The results showed that the kerosene was removed from oil/water emulsion as a result of the hydrophobic performance of the resulting membranes. And oil removal efficiency of the membrane with the mass ratio of PDMS/PVDF 1:30 and PDMS/TEOS 3:1 was the highest, about 60% of the kerosene was removed under the inlet pressure of 0.16 MPa, the emulsion temperature of 20 oC and the emulsion concentration of 10 g/L(1 wt %).