Study On Preparation Of High Performance POSS-GO/PDMS Hybrid Membrane And The Pervaporation Performance For Organic Recovery

The separation technology of pervaporation is a wide range of application prospects due to its advantages of green environmental protection,economy and energy saving.The pervaporation membrane is a key factor in this separation technology.Hybrid membranes have high research value because they combine the advantage of inorganic membranes and organic membranes.The problems of agglomeration and lossing of hybrid particles are of great significance to the preparation of high-performance separation membranes.In this thesis,the superhydrophobic composite particles were prepared,which improved the dispersion and distribution of the hybrid particles in the polymer matrix,reduced the crystallinity of the polymer,and constructed a fast mass transfer channel in the separation layer.Pervaporation preferentially penetrates organic hybrid membranes.Through various characterization methods,the microscopic morphology,physical structure and chemical structure of the membrane were characterized,and the membrane properties were analyzed and explored.Firstly,in order to improve the dispersion of the hybrid particles in the polydimethylsiloxane（PDMS）solution,cage-type silsesquioxane（POSS）nanoparticles were anchored to the two-dimensional material graphene oxide（GO）.The the superhydrophobic composite structure POSS-GO particles were fabricated,and the POSS-GO/PDMS pervaporation hybrid membrane was prepared by ultrasonic impregnation method for the recovery of ethanol in aqueous solution.The optimal film-forming conditions for the POSS-GO/PDMS hybrid membrane were further explored.When the loading of POSS-GO particles was 0.2 wt%and the feed solution with 5%ethanol content,the membrane flux could reach 1346.9 g·m^-2·h^-1 with a separation factor of 11.2.Compared with the PDMS membrane,the flux of the ethanol component is increased by 3 times,and there is no performance degradation in stable operation for 120 hours.The morphology and properties of the films were characterized by scanning electron microscopy（SEM）,atomic force microscopy（AFM）,transmission electron microscopy（TEM）,etc.,indicating that the POSS-GO particles have good dispersibility and compatibility in the casting solution.Low-field nuclear magnetic resonance（LF-NMR）was further applied to verify the physical crosslinking between the polymer chains of the POSS-GO particles.The swelling resistance of the membrane was improved,and the hybrid particles were reduced losses,during membrane operation.Secondly,in order to regulate the distribution of POSS-GO nanosheets in the separation layer and reduce the crystallinity of PDMS,the POSS-GO/PDMS hybrid membrane was prepared by a Floating-on-Water（FOW）approach to recovery the acetonitrile in water.The effects of the viscosity of the PDMS solution,particle types and loadings on the film-forming properties of the FOW approach were investigated,and the optimal preparation conditions of the hybrid membrane were obtained.The film structure and properties were determined by scanning electron microscopy（SEM）,contact angle（CA）and other characterization methods.The thickness of the separation layer was about 3μm.For 1%acetonitrile/water feed solution,the separation factor of the membrane was 26,Meanwhile,the permeate flux reached 2489 g m^-2 h^-1.Compared with PDMS membrane,the flux was 489·g m^-2·h^-1.The flux of the hybrid membrane prepared by the FOW method was increased by 4 times.The effect of the operation conditions on the membrane performance was further studied.In the 9wt%salt content,the separation factor of the hybrid membrane was up to 44 and the flux was 2249 g·m^-2·h^-1.