【作者】 孟敏佳；

【导师】 闫永胜；

【作者基本信息】 江苏大学 ， 清洁能源与环境保护， 2014， 博士

【摘要】 水杨酸类物质包括水杨酸(Salicylic Acid,SA).水杨酸甲酯(Methyl Salicylate,MS)、水杨酰胺(Salicylamide, SAM)和乙酰水杨酸(Acetylsalicylic Acid, ASA)等,广泛应用于化工、医药、食品以及美容等领域。水杨酸类化合物在生产过程中常由于原料转化不完全和分离提纯工艺落后等不足,不可避免地使产品带有多种浓度较高的副产物,同时产生大量富含水杨酸类物质的废液。由于水杨酸类化合物本身的应用大部分与人密切相关,其副产物浓度超标会直接影响人类的生命健康安全。此外,由于传统的分离富集技术难以实现对这些废液中水杨酸类物质的回收利用和变废为宝,这些具有较高回收利用价值的废液常常当作工业废水处理,造成了严重的资源浪费和经济损失。此外,这些水杨酸类废液中水杨酸物质浓度较高,一般的污水处理技术又难以处理彻底,若排放到环境中将对水体和土壤将造成不同程度的危害,影响生态平衡,并最终危害人的生命。因此,对水杨酸类化合物生产过程中富含水杨酸类物质的废液进行有效的分离富集,既可回收利用高价值的水杨酸类物质,又可防止其工业废水的产生,对实现水杨酸类化合物的“绿色生产”和“环境保护”具有重要意义。目前,水杨酸类化合物的分离富集方法主要有重结晶法、萃取法、色谱法、分子蒸馏法和膜分离法等。这些方法各具优势,但也存在其局限性。膜分离技术以其高效、节能、操作方便、分子级过滤、环境友好等优点广泛应用于工业生产过程中。但传统的膜分离技术仍存在一些限制其发展的因素,如目前的商售膜只能实现某一类物质的分离而无法实现单个物质的分离,特别是对结构相似的有机化合物。由于水杨酸类化合物结构十分相似,使用传统膜分离技术无法实现它们之间的高效分离。因此,研究开发一类高效、低能耗、绿色便捷的水杨酸类物质分离富集方法具有重要的科学、经济和社会价值。采用分子印迹技术(Molecular Imprinting Technology, MIT)制备的分子印迹聚合物(molecularly imprinted polymers MIPs)是具有分子识别能力的高分子材料,材料表面存在的印迹位点对目标分子具有特异亲和性。将MIT与膜分离技术结合制备的复合印迹膜是由结构优化的多孔支撑层和具有选择性的薄层复合而成的,其兼具了特异识别性能和优良通量的双重优点,是一种理想的分离材料。基于印迹膜材料的分离方法,一方面具备“绿色化学”能耗低、能源利用率高、便于放大连续操作等独特优势；另一方面该方法针对目前商业膜材料难以实现对单个物质选择性分离的缺陷,为将特定分子从结构类似物中分离出来提供了可行有效的解决途径。本论文采用多种表面修饰印迹聚合技术,分别合成了以聚偏氟乙烯微滤膜(PVDF)、聚丙烯微滤膜(PP)和无机氧化铝陶瓷膜(A1203)为基膜的五大类复合印迹膜,并用于选择性分离富集水杨酸类化合物；采用紫外可见光谱(UV)、红外光谱(FTIR)、拉曼光谱、扫描电镜(SEM)、透射电镜(TEM)、光电子能谱(XPS)、原子力显微镜(AFM)、接触角分析等多种手段对所合成的复合印迹膜的表面形貌、结构组成、表面润湿性、膜通量等进行了深入表征。系统研究了复合印迹膜在分离富集水杨酸类化合物过程中对目标物的吸附能力、渗透性能和动态分离性能,并详细探讨了复合印迹膜的识别机制。本论文主要研究结果如下：1.基于表面光引发聚合技术复合印迹膜的制备及其选择性分离富集性能研究以PVDF膜为基膜,SA为模板分子、N,N’-亚甲基双丙烯酰胺(MBAA)为交联剂,苯甲酮(BP)为光引发剂,采用紫外光引发印迹聚合技术制备了分别以甲基丙烯酸(MAA)、丙烯酰胺(AM)和4-乙烯基毗啶(4-VP)为功能单体的3类复合印迹膜,依次为：MAA-MIM、AM-MIM和4-VP-MIM。采用UV、SEM、FTIR、拉曼光谱等技术对所合成的三类MIM的形貌和结构进行了表征。静态动力学实验表明,在10min内MAA-MIM, AM-MIM和4-VP-MIM对SA的吸附几乎均达到平衡。从等温吸附曲线可以得出,以4-VP为功能单体所合成的4-VP-MIM具有较好的吸附效果,且随着功能单体浓度的增大,4-VP-MIM对SA的吸附容量也随之增大。选择性实验结果表明,4-VP-MIM对SA的选择性优于相应MAA-MIM和AM-MIM,且发现功能单体用量的多少影响MIM的选择性。通过紫外光谱和核磁共振氢谱结合阐述了MAA-MIM, AM-MIM和4-VP-MIM性能差异的原因,认为可能的识别机理是SA和4-VP之间的离子键作用强于SA和MAA以及AM之间的氢键作用力。渗透性实验表明4-VP-MIM对SA和ASA的分离符合延迟渗透传质机理。2.基于溶胶-凝胶技术复合印迹膜的制备及其选择性分离富集性能研究(1)采用无机A1203陶瓷膜为基膜,对羟基苯甲酸(p-HB)为印迹分子,分别以异氰酸丙基三乙氧基硅烷(ICPTES)和3-氨丙基三乙氧基硅烷(APTES)为功能单体,正硅酸四乙酯(TEOS)为交联剂,盐酸(HCl)为催化剂,采用溶胶-凝胶技术制备2类对羟基苯甲酸复合印迹膜即非共价复合印迹膜(NCIM)和半共价复合印迹膜(SCIM)。采用FTIR和SEM表征手段研究了NCIM和SCIM的结构和形貌特征。通量测试表明2种复合印迹膜表面的印迹聚合物有利于增大膜通量；二元选择性实验结果表明了SCIM和NCIM对p-HB都具有特异选择性；SCIM对p-HB和SA的选择性分离系数为3.120,明显高于NCIM的相应值,证明采用半共价印迹聚合法制备的印迹膜对p-HB具有更高的选择性；渗透性实验揭示了SCIM和NCIM对SA和p-HB的渗透符合促进渗透传质机理。动态分离实验采用3因素3水平的响应曲面BBD卖验优化法对SCIM对p-HB和SA选择性分离的主要影响因素(如：混合溶液中p-HB的浓度、分离温度和溶液的流速等)进行了优化,得到的最佳动态分离条件即：p-HB的浓度为5.0mg/L,分离温度为10℃,流速为1.0mL/min。(2)龙胆酸(GA)为模板分子,γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)为交联剂,偶氮二异丁腈(AIBN)为引发剂,室温离子液体(RTIL)为孔模板,无机Al2O3陶瓷膜为基膜,选择三种羧酸：甲基丙烯酸(MAA)、丙烯酸(AA)和肉桂酸(CA)为功能单体,制备了相应3种复合印迹膜分别为：MAA-CIAM, AA-CIAM和CA-CIAM。采用UV、FTIR、SEM、 AFM等技术研究了所合成复合印迹膜的结构和形貌特征；通量测试实验表明所合成三类复合印迹膜均具有良好孔隙率,且印迹聚合物内部结构稳定；静态吸附性实验证明CA作为功能单体制备的印迹膜具有更高的吸附量,其中交联剂用量也影响膜吸附性能；渗透性实验揭示了离子液体对印迹膜的分离效果起着关键作用；CA-CIAM2具有较高的SA传质系数(5.146×103cm/s)和较低的GA传质系数(1.233×103cm/s)说明CA-CIAM2对SA和GA具有最佳分离效果。选择3因素3水平实验设计BBD法结合响应曲面模型优化了最佳动态分离条件,即为：GA的浓度为5.0mg/L,分离温度为15℃,流速为1.0mL/min。3.基于乳液聚合技术复合印迹膜的制备及其选择性分离富集性能研究(1)以SA为模板分子,4-乙烯基吡啶(4-VP)为功能单体,司班80(Span80)为表面活性剂,甲苯为油相,乙二醇二(甲基丙烯酸)酯(EGDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,聚丙烯微孔滤膜(PP)为基膜,采用油包水型(W/O)普通乳液聚合法制备了水杨酸复合印迹聚丙烯膜(SIPM)。采用拉曼光谱、SEM、AFM和接触角测试等表征手段研究了SIPM的结构组成和形貌特征以及表面湿润性；通量测试结果表明SIPM表面的亚微米印迹聚合微球有利于增大膜通量。静态吸附实验结果揭示了SIPM对SA有特异选择性,且适当增加SIPM表面印迹聚合微球的量有利于提高SIPM对SA的吸附容量。渗透性实验证明SIPM对SA和ASA的渗透遵循促进渗透传质机理。(2)以苯酚为模板分子,4-乙烯基吡啶(4-VP)为功能单体,苯乙烯(St)为聚合单体、二乙烯基苯(DVB)为交联剂,十二烷基三甲基溴化铵(DTAB)为乳化剂,去离子水为连续相,过硫酸钾(KPS)为引发剂,Al2O3陶瓷膜为基膜,采用水包油(O/W)型微乳液聚合技术制备了苯酚复合印迹膜(CIAM)。采用UV、拉曼光谱、SEM、TEM和XPS等表征手段研究了CIAM的结构组成和形貌特征；表面活性剂的用量与油水相混合方式影响CIAM上纳米印迹微球的粒径大小。研究发现CIAM上印迹纳米微球的粒径大小影响CIAM的吸附容量和选择性能。CIAM的动态分离效果优于静态分离性能。渗透性实验中,CIAM5对SA和苯酚的选择性分离系数高达18.2,表明CIAM对苯酚的选择性随着CIAM表面的印迹纳米微球粒径的降低而增加,但纳米印迹微球粒径过小容易在CIAM表面发生团聚而不利于选择性分离。考查了人工模拟动态分离水杨酸样品中苯酚的行为以及加标回收法检测了水杨酸工业产品中的苯酚。更多还原

【Abstract】 Salicylic acid series products including salicylic acid, methyl salicylate, salicylamide and acetyl salicylic acid and so on, are widely used in the field of chemical, pharmaceutical, food, cosmetic and so on. On account of the incomplete conversion of raw materials and poor technology of separation and purification during the production process of salicylic acid series products, it will inevitably create a lot of by-products in the aim products as well as large number of the liquid waste rich in salicylic acid substance. Because most of the application of salicylic acid is closely related to people, the by-products concentration exceeded standard will directly affect human life and health safety issues. Moreover, it seems impossible to effectively recycle of salicylic acid series material in the waste liquid and turn "waste" into wealth with the traditional separation/enrichment technology. These waste liquid with high recycling value are often treated as industrial wastewater, causing serious waste of resources and economic losses. Additionally, the general sewage treatment technology is difficult to dispose of the high concentration of salicylic acid series material in the waste liquid. If released into the environment of water and soil, it will cause varying degrees of damage, and affect the ecological balance and ultimately endanger human life. Therefore, the effective separation and purification of the waste liquid during the production process of salicylic acid series products will, on the one hand, can recycle high value of salicylic acid series material, then it can prevent the formation of the industrial waste water. It is of great significance For the green production of salicylic acid products and environmental protection.At present, the main methods for the separation and enrichment of salicylic acid products are recrystallization, extraction, chromatography method, molecular distillation and membrane separation, etc. These methods have their own unique advantages, but also has its limitations. The rise of membrane separation technology with its high efficiency, energy conservation, convenient operation, molecular filtration, environment friendly advantages in the production process has been widely used in enterprises. But the membrane separation technology in traditional still exist some restrict factors of its development, such as the current commercially available membrane can realize the separation of a substance but can not achieve the separation of a single material, especially for organic compounds with similar structure. The traditional film can not show a single, highly selective separation of a substance. Therefore, it is significant to research and develop a high efficiency, low energy consumption, green and convenient purification method of salicylic acid series products. Molecularly imprinted polymers (MIPs) prepared via molecular imprinting technology (MIT) is a polymer materials with molecular recognition ability, there are many imprinted cavities on its surface which have specific affinity and recognition ability to the target molecule. Molecularly imprinted composite membrane is compounded of a optimized porous support layer structure and selective layer, which unite molecular imprinting technology and membrane separation technology. This composite membrane possesses the advantages of specific recognition excellent performance of flux, it is an ideal imprinted membrane materials. On the one hand, the technique is convenient for continuous operation, easy amplification, low energy consumption, high energy utilization rate, it is the typical "green chemistry". On the other hand, it overcomes the defect that the present commercial membrane materials such as ultrafiltration, microfiltration and reverse osmosis membrane cannot realize single substance separation. It provides a feasible and effective way to separate the specific molecular from the structure similar mixture.In this paper, using a variety of surface modification technology, on the surface of different substrate membrane (polyvinylidene fluoride microfiltration membrane, polypropylene microfiltration membrane and inorganic ceramic membrane), prepared of compound molecularly imprinted membrane which is used in the study of selective purification of salicylic acid products. Through the system analytical measurements to character the surface morphology, structural composition, hydrophobic and membrane flux of the prepared composite membranes. Studying the adsorption capacity, permeability, and the dynamic separation performance of various molecularly imprinted composite membranes for selectively recognizing salicylic acid products, and discusses the recognition mechanism in detail. The main study results of this thesis are as follows:1. The preparation of salicylic acid composite imprinted membrane by the photo-init iation polymerization method for selective separation and enrichmentThree kinds of imprinted membranes for salicylic acid:MAA-MIM, AM-MIM and4-VP-MIM, were prepared via photopolymerization based on polyvinylidene fluoride membrane (PVDF) with methacrylic acid (MAA), acrylamide (AM) or4-vinylpyridine (4-VP) as the functional monomer, respectively, and N.N’-methylene-bis-acrylamide (MBAA) as crosslinking agent, benzophenone as photoinitiator. The structure, morphology of three imprinted membrane was characterized by UV, SEM, FT-IR and Raman spectra. The static kinetics experiment indicates that adsorption equilibrium time for three imprinted membranes were all10min. The isothermal adsorption curve indicates that the membrane prepared with4-VP as functional monomer had good adsorption effect. Moreover, the adsorption capacity of4-VP-MIM for SA increases with the increase of the concentration of functional monomer. Selectivity study shows that4-VP-MIM has better selectivity than MAA-MIM and AM-MIM on SA and high functional monomer concentration affect the selectivity of MIM. The different performance among MAA-MIM, AM-MIM and4-VP-MIM was investigated by UV spectra and1HNMR. It was drawn that the ionic bonding between SA and4-VP stronger than the hydrogen bond between SA and MAA or AM may the main recognition mechanism of imprinted membrane. Permeation experiment shows that transport mechanism for permeation of the ASA and SA towards4-VP-MIM was accordance with the facilitated mechanism.2. The preparation of composite imprinted membrane by the the sol-gel method for selective separation and enrichment(1) Two kinds of composite imprinted membranes (CIAM) for p-hydroxybenzonic acid (p-HB) was prepared via hydrolytic sol-gel method based on alumina membrane by using p-HB as the template molecule,(3-isocyanatopropyl) triethoxysilane (ICPTES) or aminopropyltriethoxysilane (APTES) as the functional monomer, the tetraethoxysilane (TEOS) as the cross-linker, and hydrochloric acid as the catalyst. The structure, morphology of CIAM was characterized by FT-IR and SEM. Flux test shows that the imprinted polymer layer on the membrane is helpful to increase the membrane flux. Binary selective experiments shows CIAM can selective rebind the p-HB, moreover, Compared with composite imprinted membrane via non-covalent imprinting approach (NCIM), the SCIM exhibited higher selective separation factor (3.120), showing excellent selectivity for p-HB. Permeation experiment show that transport mechanism for permeation of the p-HB and SA towards SCIM or NCIM was accordance with the facilitated mechanism. Response surface methodology of a three level, three variable Box-Behnken design (BBD) was applied to determine the best dynamic separation parameters for optimizing the separation process including the the concentration of p-HB (mg/L), the temperature (℃) and the flow rates (mL/min). The optimal conditions for the separation of p-HB from SA were as follows:the p-HB concentration of5.0mg/L, the temperature of10℃and the flow rate of1.0mL/min.(2) Three kinds of composite imprinted membranes (CIAM) for gentisic acid (GA) was prepared via room temperature ionic liquid (RTIL)-mediated nonhydrolytic sol-gel (NHSG) methodology based on alumina membrane by using GA as the template molecule, acrylic acid (AA), cinnamic acid (CA), and methacrylic acid (MAA) as three functional monomers, RTIL as pore template, methacryloxypropyltrimethoxysilane (MPS) as the crosslinker,2,2’-azobis(2-isobutyronitrile)(AIBN) as an initiator. The structure, morphology of CIAM was studied by UV、FTIR、SEMA、AFM. Flux test shows that the CIAM have good porosity and the structure of the imprinted polymer on the membrane was stable. Static adsorption study show that the CIAM prepared with CA as functional monomer has higher adsorbing capacity. Additional, it is obvious that the crosslinker amount can affect the performance of the membrane. Permeation experiment show that the ionic liquid play an important role in the separation effect of CIAM. The higher SA permeability coefficients (5.146×10-3cm/s) and lower GA permeability coefficients (1.233x10-3cm/s) for CIAM2show the optimal separation effect. Additionally, a three-level Box-Behnken experimental design with three factors combining the response surface modeling was used to optimize dynamic separation process and the optimal conditions were as follows:the GA concentration of5.0mg/L, the temperature of15℃and the flow rate of1.0mL/min.3. The preparation of composite imprinted membrane by the emulsion polymerization method for selective separation and enrichment(1) The submicrosized imprinted polypropylene microfiltration membrane (SIPM) for salicylic acid (SA) was prepared via common water-in-oil emulsion polymerization method based on polypropylene microfiltration membrane by using salicylic acid as template molecule,4-vinyl pyridine as functional monomer, Span80as emulsifier, toluene as the oil phase, ethyleneglycol dimethacrylate as cross-linking agent,2,2’-azobis (2-methylpropionitrile) as initiator. The structure, morphology and surface wettability of SIPM was characterized by Raman spectra, SEM, AFM and contact angle test. Flux test shows that the submicrosized Imprinted Spheres on the membrane is helpful to increase the membrane flux. Static adsorption experiment indicates that SIPM had a selective rebinding for SA. Moreover, it will increase the adsorption amount of SA with properly increasing the amount of imprinted spheres. Permeation experiment show that transport mechanism for permeation of the SA and ASA towards SIPM was accordance with the facilitated mechanism.(2) The molecularly imprinted composite membrane (CIAM) for phenol was prepared via oil-in-water microemulsion polymerization method based on alumina membrane by using phenol as template molecule,4-vinyl pyridine as functional monomer, styrene as the monomer, N,N,N-trimethyl-l-dodecanaminium bromide as the emulsifier, deionized water as the continuous phase, divinylbenzene as cross-linking agent and potassium persulfate as initiator. The structure, morphology of CIAM was characterized by UV, Raman spectra, SEM, TEM and XPS. The amount of surfactant and the mixed mode of oil and water phase can affect the particle size of imprinted nano-spheres in the membrane. Flux test shows that CIAM possessed good porosity. The nano-spheres with different size affect the adsorption capacity and selective performance of the CIAM. In the permeation experiment, the selective separation factor of CIAM5for SA and phenol was18.2, indicating that smaller nano-spheres benefited selective separation to some extent. However, it will be bad for selective separation if the nano-spheres is too small because of their reunion. Last, simulating dynamic separation of salicylic acid and phenol as well as the detection of phenol in salicylic acid industrial products through standard addition recovery method were investigated.更多还原