Pervaporation of the polydimethylsiloxane composite membranes filled with hydroxy-terminated silicone oil modified nano-silica

A new polydimethylsiloxane (PDMS) pervaporation membrane which filled hydroxy-terminated silicone oil modified nano-silica was prepared. Firstly, we used hydroxy-terminated silicone oil to modify nano-silica (OMNS); OMNS was used as a physical cross-linking agent to modify PDMS through blending OMNS into PDMS (OMNS-PDMS). OMNS particles were tested by Fourier-transform infrared spectroscopy and sedimentation experiments. It was found that the hydroxyl group in the silicone oil could condense with the carboxyl group on the surface of nano-silica (NS) to realize hydrophobic modification. Then, the OMNS-PDMS membrane morphology and ten -sile strength were investigated by scanning electron microscope and mechanical property tests. The OMNS-PDMS membrane showed significant advantages in flux and separation compared with the unfilled PDMS membrane. When the content of OMNS was 10 wt.%, the flow rate was 7 L/min, the permeate side was maintained at a vacuum pressure of 0.82 bar, and the feed etha-nol concentration was 15 wt.%, the flux reached 682 g/(m2 center dot h), and the pervaporation separation index reached 7099.74 g/(m2 center dot h). Therefore, this work provides an excellent candidate method for pervaporation separation of dilute ethanol/water.