The Construction Of Cyclodextrin Cross-linked Modified Pervaporation Membrane And Its Separation Characteristics Of Benzene/cyclohexane

Pervaporation is an environmentally friendly new separation technology,which has unique advantages for the separation of near-boiling and azeotropic mixtures.How to construct a pervaporation membrane for the separation of organic compounds has become one of the frontier issues in the field of membrane separation.In this paper,put forward a new idea with the the cavity structure of cyclodextrin crosslinker（C.D=）and special slip structure of polyrotaxane crosslinker（PR=）design,preparation and put forward a new idea that construct new solvent-resistant pervaporation membrane,and study its benzene/cyclohexane separation characteristics.The main research contents and conclusions are as follows:（1）Using cyclodextrin molecules as the main body to prepare cyclodextrin crosslinker and polyrotaxane crosslinker successfully.Respectively using the CD=and PR= to modify the membrane,the molecular structure and properties of the membranes were characterized.The results show that the crosslinked modified membranes of CD and PR have a good homogeneous continuous structure,and the membrane of mechanical properties and thermal stability is perfect.And the solvent resistance of the membrane is improved by crosslinking.（2）The effects of temperature,liquid composition,flow rate,crosslinker content,crosslink time and membrane thickness on the pervaporation separation were investigated using benzene/cyclohexane as separation system.The results showed that at the operating temperature of 60 ℃,the composition of the feed liquid was benzene/cyclohexane（20/80 wt%）and the flow rate was 100mL/min,crosslink time of 30min,5%crosslinker content and a membrane thickness of 80μm.The performance of the PR modified membrane was better than that of CD and pentaerythritol triacrylate（PETA）.The permeation flux of CD crosslink modified membrane reached 1263g·m^-2h^-1 and the separation factor reached 5.16.The permeation flux of the PR modified membrane reached 1689g·m^-2h^-1 and the separation factor reached 6.72.The specific structure of cyclodextrin and polyrotaxane played a key role in the enhancement of membrane performance.（3）A preliminary study on the mechanism of membrane mass transfer was carried out.Based on the experimental data,it was found that benzene and membrane materials have stronger interaction and preferentially adsorbed on the membrane.By calculating the diffusion coefficient,adsorption coefficient and permeability coefficient,the difference of mass transfer rate in the membrane was discussed.The reason of the separation performance of PR modified membrane and CD modified membrane were better than that of PETA membrane was discussed.Through the calculation of activation energy and thermodynamic parameters in mass transfer process,it was found that benzene/cyclohexane compounds only need lower energy and overcome lower resistance to diffuse through the PR modified membrane,initially explained the reasons for the performance improvement of the membrane,the mechanism analysis and the actual separation performance results.