Preparation And Performance Of HKUST-1 Doped Ultrafiltration Base Membrane And Tannic Acid/Fe³⁺ Interlayer Organic Solvent Nanofiltration Membrane

The conventional organic solvent recovery process usually involves thermal phase separation process,and the recovery process using different boiling points usually has the problems of high energy consumption,high cost and easy to produce secondary pollution.In recent years,organic solvent nanofiltration（OSN）,as an emerging separation technology that uses the molecular size sieving effect of different membrane pore sizes to recover organic solvents,has the advantages of low energy consumption and low cost,and has received widespread attention in the petrochemical,pharmaceutical,food and fine chemical industries.At present,the separation performance of OSN membranes is improving through advanced membrane fabrication technology and continuous exploration of membrane materials,but OSN membranes are still facing challenges such as low solvent permeation flux and poor solvent resistance under harsh organic solvent conditions.In order to obtain OSN membranes with good performance,this paper prepares OSN membranes by optimizing the ultrafiltration base membrane and polyamide separation layer,respectively.It was found that the doping of metal organic framework（MOF）in the cast film solution can optimize the porosity and pore size distribution of the membrane in the phase transition process,which is conducive to the preparation of ultrafiltration membranes with good performance,while the construction of metal network phenols formed by the complexation reaction of tannic acid（TA）and Fe³⁺as an interlayer is conducive to the macroscopic regulation of the interfacial polymerization reaction rate and the formation of OSN membranes with ultra-thin separation layer structure.The main contents and conclusions of this thesis are as follows:（1）Preparation and performance of HKUST-1 doped polyether line imide（PEI）hybrid matrix membrane:HKUST-1/PEI hybrid matrix membrane was prepared by phase conversion method using PEI as membrane material and HKUST-1 as dopant.The changes of surface hydrophilicity,surface morphology and roughness after HKUST-1 doping in PEI ultrafiltration membrane were investigated.After testing,it was found that the HKUST-1 nanoparticle-doped hybrid matrix membrane with a mass fraction of 0.05%had a good performance,and was able to achieve a pure water flux of 1304 L·m^-2·h^-1 at an operating pressure of 0.1 MPa,with a retention rate of over 97%for a mass concentration of 1.0 g/L bovine serum albumin（BSA）.After soaking in acidic（p H=2）and alkaline（p H=12）solutions for 24 h,the rejection of BSA only decreased by about 2%（the flux of pure water remained basically unchanged）.At the high temperature of 80℃,the pure water flux reached 1587 L/（m²·h）and the BSA rejection rate was over 95%.The pollution resistance test showed that the flux recovery rate reached 92%.This shows that HKUST-1/PEI mixed matrix membrane has good acid and alkali resistance,strong high temperature resistance and excellent anti-fouling performance.（2）Preparation and performance of tannic acid/Fe³⁺interlayer organic solvent nanofiltration membrane:The mixed matrix membrane prepared in（1）was used as the base membrane,firstly,hexanediamine（HDA）was used to cross-link the base membrane to enhance the solvent resistance,and metal network phenol formed by tannic acid（TA）/Fe³⁺complexation reaction was polymerized in situ on the base membrane as the interlayer.Then,with 1%（w/v）piperazine（PIP）as the water phase and 0.2%（w/v）homophthaloyl chloride（TMC）as the organic phase,the OSN membrane was prepared by interfacial polymerization,and N,N-dimethylformamide（DMF）was used for solvent activation to further enhance the membrane flux.The changes of surface hydrophilic properties,separation layer thickness,surface charge,surface morphology and roughness of the OSN membranes containing TA/Fe³⁺interlayer were investigated.It was found that the ethanol flux of the PA-Fe₃³⁺-HDA/PEI membrane reached 28.56 L/（m²·h）and the MB rejection was over 94%in 0.1 g/L methyl blue（MB）ethanol solution under 0.6 MPa operating pressure.The average flux recovery rate of PA-Fe₃³⁺-HDA/PEI membrane was 84%,which was found to have better fouling resistance than PA-HDA/PEI membrane,and better stability performance was found by different solvent immersion experiments and continuous operation in0.1 g/L MB ethanol solution.