Preparation of thermoresponsive PVDF/SiO2-PNIPAM mixed matrix membrane for saline oil emulsion separation and its cleaning efficiency

Thermoresponsive polyvinylidene fluoride/silica-poly (N-isopropylacrylamide) (PVDF/SiO2-PNIPAM) mixed matrix membranes were synthesized using diffusion induced phase separation techniques via direct blending method. The effects of SiO2-PNIPAM particle concentrations and surface cavity size on membrane physicochemical properties were investigated through oil emulsion separation using cross-flow ultrafiltration. Compared with pristine PVDF membrane, the PVDF/SiO2-PNIPAM membrane showed higher alternated thermal cleaning ratios (N = 2.04) especially at higher SiO2-PNIPAM particle concentrations. Proper control of cavity size allows better particles actuation and minimized the surface roughness that would induce fouling phenomenon. The flux recovery ratio of 69.91% can be achieved by preparing the membrane using dope solution at 25 °C, coagulation bath temperature at 40 °C at particle dosage of 1.0 wt.% (M25-40/1.0). It was found that the actuation force as a result of temperature swing is responsible for loosening the irreversible fouling layer (gel layer) on the membrane surface.