Study On Preparation And Properties Of Polydimethylsiloxane (PDMS) Pervaporation Membranes

Ethanol,methanol,and other important organic solvents are widely used in chemical synthesis and chemical separation.High concentration ethanol solutions can be separated and concentrated by traditional separation processes such as extraction and distillation,while recovering ethanol from low concentration solutions costs significant energy and complex processes.Pervaporation is a new membrane separation technology,which is more efficient and easily coupled with other separation technologies.Using the high affinity of pervaporation membrane with ethanol in the separation system,ethanol molecules can preferentially penetrate the separation membrane to achieve ethanol enrichment in low concentration ethanol solutions.Polydimethylsiloxane(PDMS)is a hydrophobic,ethanol friendly membrane material that has been widely studied in the field of organic solvent recovery.However,PDMS pervaporation membranes are usually dense membranes that utilize the dissolution diffusion mechanism to achieve the separation of ethanol/water systems.Due to the high permeability resistance of dense membranes,it is difficult to achieve simultaneous modification of selectivity and flux.In order to break through the “trade-off” effect of PDMS membranes,different dimensional carbon nanomaterials,carbon nanotubes(CNTs)and reduced graphene oxide(r GO),were selected as fillers to prepare PDMS mixed matrix membranes.These three nano carbon materials have an affinity for ethanol molecules,which can improve the selectivity of PDMS membranes;The nano pore structure of nano carbon materials and the gap between nano carbon materials and PDMS matrix both provide a fast permeation channel for ethanol molecules.Therefore,PDMS mixed matrix membranes break through the “trade-off” effect and achieve simultaneous flux and selectivity improvements.According to the design idea of this article,the following research has been carried out:1.Study on the preparation process of PDMS membranes.The effects of crosslinking agent,time,and temperature on the structure and properties of PDMS membranes were studied,and the optimal preparation process was determined.2.Effects of one-dimensional carbon nanomaterials CNTs and r GO on the structure and properties of PDMS membranes.The aggregation state of CNTs and r GO in PDMS membranes,the microstructure changes and performance changes of PDMS membranes were studied.3.“Effects of mixed dimensional carbon nanomaterials on the structure and properties of PDMS membranes”.The interaction between CNTs and r GO and their influence on the structure and properties of the membrane were studied.4.The pervaporation performance of PDMS membrane was comprehensively analyzed,and the influence of membrane process on the pervaporation performance was explored.The long-term operation stability of the membrane laid a foundation for industrial application.