Bioinspired Synthesis Of Molecularly Imprinted Nanocomposite Membrane For Selective Separation And Mechanism Research Of Ibuprofen

In recent years,a new kind of pollution,Pharmaceutical and personal care products（PPCPs）appreaed in water,which have bioaccumulative,persistence and ecotoxicity and would be enriched in human’s body through food chain and drinking water.Reportedly,non-steroidal anti-inflammatory drugs（NSAIDs）and antibiotics had made a prominent impact on ecological and human’s health.Ibuprofen has been widely used as NSAIDs with anti-inflammatory,analgesic and antipyretic effects.Studies found that it would also make a great impact on the ecological environment even low levels of ibuprofen contained in water.Therefore,it is urgent to find a method to effectively separate and enrich the residual ibuprofen in the aquatic environment.As an interdisciplinary technology,membrane separation technique（MST）has been widely used in the fields of medicine,chemical industry,food,biological engineering and energy engineering since the 1990s with the advantages of easy preparation,low energy consumption and no secondary pollution.However,some macromolecules can easily plug the holes and adhere to the surface of membrane materials,resulting in the membrane flux decreased irreversibly and thus the service life of the membrane material reduced significantly.Therefore,membrane fouling has become a key factor restricting the development of MST.According toreports,dopamine（DA）hasgoodhydrophilicityand self-polymerization capacity,the hydrophilic modification of the membrane materials using DA to improve the internal and surface hydrophilicity.At the same time,polydopamine（pDA）formed by self-polymerization of DA can be used as a multifunctional secondary reaction platform for surface modification of nanoparticles,which avoid the agglomeration of nanoparticles on the surface or inside of the membrane materials to improve the overall performance.MST has obvious advantages when compared with other separation techniques.However,conventional MST could only separate a certain kind of material while cannot separate some specific molecules.Therefore,it is urgent to prepare a new kind of membrane separation technique with high selectivity to solve the above-mentioned problem simplely and effectively.Under this background,molecularly imprinted membranes（MIMs）appeared which combined the advantages of MST and molecular imprinting technique（MIT）for the selective separation of target molecules from mixture and the structural analogues.Therefore,the combination of MIMs and pDA modification technology to prepare a bioinspired molecularly imprinted nanocomposite membrane is of great significance for the selectivity,permeability and regeneration of the membrane materials.In this paper,inspired from DA self-polymerization composite technology,a novel bioinspired molecularly imprinted nanocomposite membrane was systhesized combining with nanocomposite modification technology and molecularly imprinted membrane technology for selective separation and enrichment of ibuprofen.Different nanoparticles were modified by DA self-polymerization composite technology and blended into PVDF to prepare nanocomposite membranes.Bioinspired molecularly imprinted nanocomposite membranes were synthesized by different surface imprinted techniques.The surface morphology,microstructure,elemental composition and bonding mode of the synthesized nanoparticles and membrane materials were systematically studied and analyzed by different analytical methods,such as scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,atomic force microscopy（AFM）,X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）and Fourier transform infrared spectroscopy（FT-IR）.Study on the kinetics and isotherms adsorption towards ibuprofen template molecules of the as-prepared bioinspired molecularly imprinted nanocomposite membranes and the corresponding adsorption kinetic and isothermal models were established,the possible mass transfer mechanisms were also described.The main findings of this thesis are as follows:1.Preparation of molecularly imprinted nanocomposite membranes based-Au@polyaniline for selective enrichment and separation of ibuprofenPVDF was used as basement membrane,the nanocomposite membranes were prepared by Au@polyaniline nanocomposites.A new type of molecularly imprinted nanocomposite membranes（MINcMs）were prepared by ATRP using ibuprofen,AM,EGDMA and Br-Au@polyaniline as template molecules,functional monomer,crosslinking agent and initiator,respectively.The surface morphology,adsorption properties and permselectivity of the different membrane materials were studied in detail.The adsorption capacity of MINcMs to ibuprofen was four times higher than that of NINcMs and the selectivity factor reached 4.67.According to the permselectivity experiments,the permselectivity factor for ibuprofen by MINcMs was 8.74.The possible mass transfer mechanisms of MINcMs were also revealed.Finally,the high selectivity adsorption and separation capacities of MINMs to ibuprofen made MINMs have a wide application prospect for the separation and enrichment of ibuprofen in water.2.Synthesis of bioinspired molecularly imprinted nanocomposite membranes assembled with dendrites-like Ag microspheres for high-selective adsorption and separation of ibuprofenInspired from DA self-polymerization composite technology,bioinspired nanocomposite membranes were prepared by pDA@GO nanosheets used as the highly adjustable active domains.The overall properties of the membrane materials were increased by reducing Ag⁺to the dendrites-like Ag microspheres.Finally,Bioinspired molecularly imprinted nanocomposite membranes（MINMs）were synthesized by sol-gel technique using ibuprofen,APTES,TEOS,and NH₃.H₂O as template molecule,functional monomer,cross-linking agent and catalyst,respectively.The surface morphology,adsorption properties and permselectivity of the different membrane materials were investigated by a variety of characterization methods.Results showed that the hydrophilicity and water flux of the MINMs were significantly improved.The max adsorption capacity was obtained by optimizing the synthesis conditions and the adsorption experiments showed that MINMs had a high adsorption capacity(61.55 mg g^-1).The permselectivity experiments showed that MINMs had a strong selectivity for ibuprofen(β_{ketoprofen/ibuprofen} andβ_{naproxen sodium/ibuprofen} up to 6.55 and 6.63).Finally,the as-prepared MINMs greatly promoted the separation of ibuprofen and the excellent permselectivity of the membrane materials based on ibuprofen made MINMs have an extremely valuable in industrial applications.3.Synthesis bioinspired molecularly imprinted nanocomposite membranes based on pDA@TiO₂ functionalized nanoparticles for selective separation of ibuprofenTo improve the separation property of membrane materials,pDA@TiO₂ nanoparticles were synthesized with DA self-polymerization compositemodificationtechnology.Functionalnanocomposite membranes（FN-CMs）were prepared using pDA@TiO₂ as functional nanoparticles.Ibuprofen imprinted nanocomposite membranes（IINCMs）were finally synthesized by sol-gel technique using ibuprofen,APTES,TEOS and NH₃.H₂O as template molecules,functional monomer,crosslinking agent and catalyst,respectively.The surface morphology,adsorption properties and permselectivity of different membrane materials were examined using a variety of characterization techniques.Results showed that the hydrophilicity of IINCMs was significantly increased.The adsorption studies showed IINCMs had a higher adsorption capacity(42.14 mg g^-1).Permselectivity experiments showed the as-prepared IINCMs had a strong selectivity for ibuprofen.Finally,the excellent selective adsorption and separation perproties of IINCMs to ibuprofen make IINCMs have great application value in the separation of pharmaceuticals,biological macromolecules and chromatographic techniques.