【作者】 潘建明；

【导师】 闫永胜；

【作者基本信息】 江苏大学 ， 环境工程， 2012， 博士

【摘要】 随着酚类精细化工原料、农药、防腐剂、灭螺剂、抗氧化剂等在工农业生产中的广泛使用,我国部分地区的酚类环境内分泌干扰物(PEDs)污染严重,其环境持久性、生物累积性、高毒性和类雌激素活性也逐步引起了人们的关注。目前,吸附分离法因为操作简单、成本低廉和不易产生二次污染而被广泛应用于PEDs的常规处理。但活性碳、改性粘土矿物、活化的下水道淤泥和生物吸附剂等常见的吸附剂普遍存在着选择性差、吸附容量小和平衡时间长等缺点。分子印迹技术(MIT)制备的分子印迹聚合物(MIPs)是具有分子识别能力的高分子材料,其内部的印迹孔穴对模板分子具有特异亲和性及识别能力。传统的MIPs一般用本体聚合制备,但从高度交联的高分子网络中萃取出模板分子很困难,制备的MIPs存在模板分子不能完全脱除、吸附容量低和动力学性能差等缺点。表面分子印迹技术通过把分子识别位点建立在载体材料表面,可以进一步提高MIPs的吸附容量和识别动力学性能。由于形貌结构特殊、比表面积大、化学稳定性高、来源易得和成本低廉等优势,硅基微/纳米粒子是理想的表面印迹载体材料。本论文采用天然硅基材料(如凹凸棒土和埃洛石纳米管)和合成硅基材料(如硅胶和粉煤灰空心微珠等)为印迹载体,将表面分子印迹技术分别与接枝共聚技术、磁性载体分离技术、温敏型智能吸附/释放技术耦合制备了新型的硅基接枝共聚分子印迹吸附剂(MIPs)、磁性分子印迹吸附剂(MMIPs)和温敏型磁性分子印迹吸附剂(TMMIPs);通过系统的测试手段分析了制备的三类印迹吸附剂的晶相、形貌、磁性、结构、元素组成、热稳定性及表面特征等；结合静态吸附实验研究了三类印迹吸附剂选择性吸附分离几种典型PEDs的行为；详细探讨了识别机制,阐述了吸附分离过程的平衡和动力学等性能。本论文主要研究结果如下：1.硅基接枝共聚表面印迹吸附剂的制备及其选择性吸附分离PEDs的研究(1)利用快速原位聚合法首先制备了聚苯胺／硅胶复合材料(PAS),接着以PAS为载体材料、接枝的氨基为功能单体、2,6-二氯苯酚(2,6-DCP)为模板分子,结合接枝共聚技术和表面分子印迹技术制备了MIPs。利用多种表征手段研究了MIPs的结构和形貌特征,结果表明MIPs呈无规则、有介孔的块状,且PAS和印迹聚合层的兼容性好。静态吸附实验表明,测试溶液的甲醇含量为3.0%和pH=7.0是最佳的吸附环境。Langmuir模型较好地描述了MIPs对2,6-DCP的吸附平衡行为,298 K、308 K和318 K时MIPs的单分子层吸附容量分别为43.59 mg/g、58.99 mg/g和63.83 mg/g。准二级动力学模型对MIPs吸附2,6-DCP的动力学数据有较好地拟合效果。粒子内扩散系数(ki)和孔扩散系数(D2)随着2,6-DCP浓度和温度的升高而增大,而膜扩散系数(D1)却随着浓度增大而减小,MIPs的吸附动力学性能优于非印迹化合物(NIPs)。选择性实验表明MIPs对2,6-DCP有显著的专一识别性。(2)选用内部空腔具有疏水性而腔外羟基具有亲水性的p-环糊精(p-CD)作为接枝剂制备了β-环糊精/凹凸棒土复合材料(p-CD/ATP),以β-CD/ATP为载体材料、表面接枝的β-CD为功能单体、2,4-二氯苯酚(2,4-DCP)为模板分子,结合接枝共聚和表面分子印迹技术制备了MIPs。利用多种表征研究了MIPs的结构和形貌特征,结果表明制备的MIPs是由直径为4.0 um的均一尺寸微球组成,且(3-CD/ATP和印迹聚合层的兼容性好。静态吸附实验表明,pH=2.0为MIPs吸附2,4-DCP的最佳条件,且主要的识别机制是氢键作用。Langmuir等温模型较好地拟合了MIPs的吸附平衡数据,298 K、308 K和318 K的单分子层饱和吸附容量分别为62.14 mg/g、70.95 mg/g和77.96 mg/g。准二级动力学模型对MIPs吸附2,4-DCP的动力学数据有较好地拟合效果,且MIPs的动力学性能优于NIPs。选择性实验和再生实验表明MIPs对2,4-DCP具有显著的选择性识别和再生性能。2.硅基表面印迹磁性吸附剂的制备及其选择性吸附分离PEDs的研究(1)利用共沉淀法制备了凹凸棒土磁性复合材料(ATP/Fe3O4),结合表面分子印迹技术制备了基于ATP/Fe3O4的MMIPs,并将获得的MMIPs应用于选择性识别2,4-DCP。利用多种表征手段研究了MMIPs的结构、形貌和磁性能,结果表明棒状MMIPs表面的印迹聚合层厚度约为16 nm,且具有超顺磁性(饱和磁强度Ms=5.67emu/g)和热稳定性。采用静态吸附实验考察了MMIPs的吸附容量、结合动力学和专一性识别效果。Langmuir等温线方程较好地拟合了MMIPs的结合平衡数据,298 K时MMIPs的饱和吸附容量为145.79 mg/g。利用准二级动力学方程、初始吸附时间和半吸附时间较好地描述了MMIPs的结合动力学行为。选择性识别实验表明,在其它结构类似的酚类化合物存在下,MMIPs对2,4-DCP具有优越的亲和力和识别能力。五次再生后MMIPs对2,4-DCP的吸附容量仅减少7.53%,同时MMIPs选择性固相萃取环境水样中2,4-DCP的效果显著。(2)利用高温分解法制备了埃洛石纳米管磁性复合材料(MHNTs),结合表面分子印迹技术制备了基于MHNTs的MMIPs,并将获得的MMIPs应用于选择性识别2,4,6-三氯苯酚(6-TCP)。利用多种表征手段研究了MMIPs的结构、形貌和磁性能,结果表明MMIPs的印迹聚合层厚度为5.0-15 nm,且具有超顺磁性(Ms=2.74 emu/g)和热稳定性。采用静态吸附实验研究了MMIPs对6-TCP的吸附平衡、动力学和选择性识别性能。Langmuir等温线方程能较好地拟合MMIPs的结合平衡数据,298 K时MMIPs的单分子层吸附容量为246.73 mg/g。准二级动力学方程、初始吸附时间和半吸附时间较好地描述了MMIPs的结合动力学行为。选择性识别实验表明,在其它结构类似的酚类化合物存在下,MMIPs对6-TCP具有较高的选择性吸附能力,且氢键作用可能是6-TCP和MMIPs结合位点之间主要的识别机制。五次再生后,MMIPs在6-TCP溶液中的吸附容量损失11.0%,在共存酚类化合物溶液中的吸附容量损失16.1%。同时MMIPs选择性固相萃取环境水样中6-TCP的效果显著。(3)利用乳液聚合法制备了粉煤灰空心微珠磁性复合材料(MCs),结合表面印迹技术制备了基于MCs的MMIPs,并将获得的MMIPs应用于选择性识别双酚A(BPA)。利用多种表征手段对MMIPs的形貌、结构、磁性和热稳定性进行表征,结果表明MMIPs为球形,具有超顺磁性(Ms=2.221 emu/g)、热稳定性和磁稳定性。采用静态吸附实验研究了MMIPs对BPA的吸附平衡、动力学行为和选择性识别性能。Langmuir等温线方程能较好地拟合MMIPs的结合平衡数据,298 K时MMIPs的单分子层吸附容量为135.1 mg/g。MMIPs的动力学行为可用准二级动力学方程描述。选择性识别实验表明,MMIPs对BPA具有较好地亲和力和选择性,且氢键作用可能是BPA和MMIPs结合位点之间主要的识别机制。通过实际样品测试,表明MMIPs选择性固相萃取环境水样中BPA的效果显著。3.硅基表面印迹温敏型磁性吸附剂的制备及其选择性识别／释放PEDs的研究(1)首先利用溶剂热法制备了Fe3O4/埃洛石纳米管磁性复合材料(MHNTs),其次分别以乙烯基改性的MHNTs (MHNTs-MPS)为载体材料、2,4,5-三氯苯酚(5-TCP)为模板分子、N-异丙基丙烯酰胺(NIPAM)为温敏单体,结合表面分子印迹技术制备了TMMIPs。TMMIPs具有超顺磁性(Ms=2.026 emu/g)、磁稳定性、热稳定性和较好地温敏效果。核磁共振氢谱(1H-NMR)和紫外吸收光谱研究了MAA和5-TCP之间的相互作用,验证了氢键作用是TMMIPs对模板分子主要的识别机制。静态吸附和释放实验表明,60℃时MMIPs对5-TCP的饱和吸附容量为197.8 mg/g；20℃时吸附的5-TCP中约有32.3%-42.7%被释放出来。动力学研究证实了TMMIPs比温敏型磁性非印迹聚合物(TMNIPs)具有较快的吸附和释放动力学性能。选择性实验结果表明,TMMIPs对5-TCP具有高的亲和力和选择性识别能力。(2)利用湿法浸渍技术将CoFe2O4置于HNTs的空腔内制备了埃洛石纳米管磁性复合材料(MHNTs),利用过硫酸铵链引发的热聚合反应制得了α-甲基丙烯酸(MAA)功能化的磁性埃洛石纳米管(MAA-MHNTs),通过在MAA-MHNTs表面接枝温敏单体NIPAM,获得了NIPAM功能化的磁性埃洛石纳米管(NIPAM-MHNTs)。分别以5-TCP为模板分子、NIPAM-MHNTs为载体材料制备了TMMIPs。TMMIPs具有较好地磁分离效果(Ms=1.758 emu/g)、磁稳定性、热稳定性(尤其在200℃以下)和显著的温敏行为。静态吸附和释放实验表明,通过改变测试液温度可以实现TMMIPs对5-TCP可控的吸附和释放功能。在高温条件下(如60℃),TMMIPs对5-TCP的饱和吸附容量可达197.7 mg/g；在低温下(如20℃),部分吸附的5-TCP可以从TMMIPs中释放出来。动力学研究结果证实了TMMIPs对5-TCP的吸附和释放动力学性能优于TMNIPs。选择性实验的结果表明,TMMIPs对5-TCP具有高的亲和性和选择性识别性能。更多还原

【Abstract】 With the widespread use of phenolic fine chemical industrial raw materials, pesticide, preservatives, molluscicide and antioxidants in the industrial and agricultural production, the pollutions from phenolic endocrine disruptors (PEDs) are serious in a few parts of China. Moreover, the toxicity, environmental persistence, bioaccumulation and estrogenic activity of PEDs have aroused wide public concern. In regular monitoring, adsorption that utilizes sorbents is an efficient and economically feasible method for the removal of PEDs. Currently, sorbents such as activated carbon, modified clay materials, biosorbents and sewage sludge all have the disadvantages of low selectivity, small adsorption capacity and long equilibrium time.Molecular imprinting technology (MIT) is a promising method to prepare synthetic materials with molecular recognition ability, namely molecularly imprinted polymers (MIPs). And the artificial receptor-like binding sites in MIPs having the size and shape complimentary to the template molecule. Traditionally, MIPs, obtained by bulk polymerization, exhibit highly selective recognition but with low capacity and poor site accessibility to the target molecules, as the extraction of template molecules embedded inside the thick polymer network is quite difficult due to the high cross-linking nature of MIPs. By establishing the molecular recognition system to be located at or near the surface of support materials, surface imprinting technique provides a promising solution to improve the adsorption capacity and recognition kinetics by reducing permanent entrapment of the template. Micro/nano silicon-based materials have the potential to be adopted as the imprinting support materials because of their low cost, chemical stability, large surface area together with readily obtainable property.In this study, the natural silicon-based materials (attapulgite and halloysite nanotubes) and synthetic silicon-based materials (silica gel and fly-ash-cenospheres) were adopted as the imprinting support. Then the MIPs, magnetic molecularly imprinted polymers (MMIPs), temperature responsive and magnetic molecularly imprinted polymers (TMMIPs) were prepared by surface imprinting technology incorporating with the graft copolymerization technology, magnetic material separation method and temperature responsive adsorption/release technology, respectively. By various of characterization, the crystalline phase, morphology, magnetism, structure, chemical composition and surface property of as-prepared imprinted sorbents were investigated. And their behaviours of selective rocognition and separation of several typical PEDs were studied by the batch mode operations. Moreover, the recognition mechanism, adsorption equilibrium and kinetics were discussed in detail.The main conclusions included the following items:1. Synthesis of MIPs upon silicon-based materials by graft copolymerization and research of applications in selective adsorption and separation PEDs(1) Polyaniline/silica gel composites (PAS) were prepared by in situ fast polymerization method. Using PAS, grafted amido and 2,6-dichlorophenol (2,6-DCP) as the support, functional monomer and template, respectively, MIPs were synthesized by graft copolymerization. Then the MIPs were characterized, and the results demonstrated agglomerate shape possessed of mesopores, and the good compatibility was obtained between the PAS and imprinted layer. The results of batch adsorption experiments suggested that pH 7.0 and the 3.0% volume of methanol in testing solution were the optimal adsorption conditions. The Langmuir isotherm model was fitted to the equilibrium data better than the other models, and the monolayer adsorption capacity of MIPs were 43.59 mg/g,58.99 mg/g and 63.83 mg/g at 298 K,308 K and 318 K, respectively. The kinetic properties of MIPs were well described by the pseudo-second-order equation. Moreover, intraparticle diffusion coefficient (k\) and pore diffusion coefficient (D2) of MIPs elevated with the increased of 2,6-DCP concentration and temperature of medium, while increased the 2,6-DCP concentration was found to reduce film diffusion. Furthermore, the values of film diffusion coefficient (D1) were lower than those of D2, indicating the diffusion process was controlled by film diffusion. The selectivity of the MIPs also demonstrates high affinity for 2,6-DCP over related phenolic compounds, and the recognition activity was excellent than that of non-imprinted polymers (NIPs).(2) In order to improve the selectivity in the presence of polar solvents, especially water,β-cyclodextrin (β-CD), possessing of a hydrophilic exterior and hydrophobic internal cavity, was used to prepare the (3-cyclodextrin/attapulgite composites (β-CD/ATP). Usingβ-CD/ATP, graftedβ-CD and 2,4-dichlorophenol (2,4-DCP) as the support, functional monomer and template, respectively, MIPs were synthesized by graft copolymerization. Then the MIPs was characterized, and the results demonstrated uniformLy sized microspheres with the diameter of 4.0 um, and the good compatibility was obtained between theβ-CD/ATP and imprinted layer. The results of batch adsorption experiments suggested that pH 2.0 in testing solution was the optimal adsorption condition, and hydrogen bonding was the main recognition mechanism. The Langmuir isotherm model was fitted to the equilibrium data better than the other models, and the monolayer adsorption capacity of MIPs were 62.14 mg/g,70.95 mg/g and 77.96 mg/g at 298 K,308 K and 318 K, respectively. The kinetic properties of MMIPs were well described by the pseudo-second-order equation. Moreover, MIPs demonstrated higher affinity for target 2,4-DCP and excellent regeneration property.2. Synthesis of MMIPs upon silicon-based materials and research of applications in selective adsorption and separation PEDs(1) Via encapsulation of attapulgite/Fe3O4 magnetic particles (ATP/Fe3O4), the MMIPs were synthesized for the selective recognition of 2,4-DCP. MMIPs were characterized, and the results demonstrated claviform shape with an imprinted polymer film (thickness of about 16 nm), and exhibited magnetic property (Ms=5.67 emu/g) and thermal stability. Batch mode adsorption studies were carried out to investigate the specific binding capacity, binding kinetics and recognition specificity. The Langmuir isotherm model was fitted to the equilibrium data better than the other models, and the monolayer adsorption capacity of MMIPs were 145.79 mg/g at 298 K. The kinetic properties of MMIPs were well described by the pseudo-second-order equation, initial adsorption rate and half-adsorption time. The selective recognition experiments demonstrated high affinity and selectivity towards 2,4-DCP over structurally related phenolic compounds. In addition, MMIPs could be regenerated, and their adsorption capacity in the fifth use was about 7.53%loss in 2,4-DCP solution. Moreover, MMIPs were successfully applied to the selective solid phase extraction of 2,4-DCP from environmental water samples.(2) Magnetic nanoparticles were attached to carboxylic acid functionalized halloysite nanotubes (COOH-HNTs) by high-temperature reaction of ferric triacetylacetonate in 1-methyl-2-pyrrolidone. Based on magnetic halloysite nanotubes particles (MHNTs), MMIPs were synthesized for the selective recognition of 2,4,6-trichlorophenol (6-TCP). MMIPs were characterized, and the results demonstrated with an imprinted polymer film (5.0-15 nm) and exhibited magnetic property (Ms=2.74 emu/g) and thermal stability. Batch mode adsorption studies were carried out to investigate the specific adsorption equilibrium, kinetics, and selective recognition. The Langmuir isotherm model was fitted to the equilibrium data better than the other model, and the monolayer adsorption capacity of MMIPs was 246.73 mg/g at 298 K. The kinetic properties of MMIPs were well-described by the pseudo-second-order equation, initial adsorption rate, and half-adsorption time. The selective recognition experiments demonstrated high affinity and selectivity toward 6-TCP over structurally related phenolic compounds, and hydrogen bonds between 6-TCP and methacrylic acid (MAA) were mainly responsible for the recognition mechanism. In addition, MMIPs could be regenerated, and their adsorption capacity in the fifth use was about 11.0% loss in pure 6-TCP solution, about 16.1% loss in coexisting phenolic compound solution. The MMIPs prepared were successfully applied to the selective solid phase extraction of 6-TCP from environmental samples.(3) Magnetic composites (MCs) were achieved via coating a chitosan layer containing y-Fe2O3 nanoparticles onto the surface of aldehyde-functionalized fly-ash-cenospheres. Based on these MCs, MMIPs were further synthesized and characterized, and used to selectively recognise bisphenol A (BPA) molecules. MMIPs were characterized, and the results demonstrated that these spherical shaped MMIPs particles had magnetic sensitivity (Ms=2.221 emu/g) and magnetic stability. Batch mode adsorption studies were carried out to investigate the specific adsorption equilibrium, kinetics and selective recognition. The Langmuir isotherm model was fitted well to the equilibrium data of the MMIPs, and the monolayer adsorption capacity of the MMIPs was 135.1 mg/g at 298 K. The kinetic properties of the MMIPs were well described by the pseudo-second-order equation. Selective recognition experiments demonstrated the high affinity and selectivity of MMIPs towards BPA over competitive phenolic compounds, and hydrogen bonding was proved to be mainly responsible for the recognition mechanism.3. Synthesis of TMMIPs upon silicon-based materials and research of applications in selective recognition and release PEDs(1) FesCVHalloysite nanotube magnetic composites (MHNTs) were firstly prepared via an effective polyol-medium solvothermal method, and then the surface of the MHNTs was endowed with reactive vinyl groups through modification with 3-(methacryloyloxy)propyl trimethoxysilane (MPS). Based on the MHNTs-MPS, TMMIPs were further synthesized by adopting 2,4,5-trichlorophenol (5-TCP) and N-isopropylacrylamide (NIPAM) as the template molecules and temperature responsive monomer, respectively. TMMIPs were characterized and the results indicated that the TMMIPs exhibit magnetic sensitivity (Ms=2.026 emu/g), magnetic stability and thermal stability and excellent temperature responsive behavior. The molecular interaction between 5-TCP and MAA was investigated by 1H-NMR spectroscopy and ultraviolet absorption spectroscopy, which suggested that hydrogen bonding may be largely responsible for the recognition mechanism. The TMMIPs were then applied to selectively recognise and release 5-TCP molecules at 60℃and 20℃, respectively. The maximum amount of binding at 60℃was 197.8 mg/g for TMMIPs. At 20℃, about 32.3%-42.7% of 5-TCP adsorbed by TMMIPs was released. The kinetic results suggested that the TMMIPs possessed of a faster adsorption and recognition of 5-TCP than that of temperature responsive and magnetic non-imprinted polymers (TMNIPs). The selective recognition experiments demonstrated the high affinity and selectivity of TMMIPs towards 5-TCP over competitive phenolic compounds.(2) CoFe2O4/halloysite nanotube magnetic composites (MHNTs) were firstly achieved via a wet impregnation technique, and then a thermal polymerization under (NH4)2S2O8 chain initiation in water was employed to obtain the methacrylic acid-functionalized MHNTs (MAA-MHNTs). By decorating the MAA-MHNTs with temperature responsive monomer N-isopropylacrylamide (NIPAM), TMMIPs based on the obtained NIPAM-MHNTs were synthesized by a surface imprinting technique. The results of characterization indicated that TMMIPs exhibited magnetic sensitivity (Ms= 1.758 emu/g), magnetic stability, thermal stability and obvious temperature responsive behavior. Then the TMMIPs were applied to switched recognition and release 5-TCP by changing the medium temperature. TMMIPs showed outstanding recognition ability towards the imprint species under high temperature conditions, the maximum amount of binding at 60℃was 197.7 mg/g for TMMIPs. At 20℃, a portion of captured 5-TCP was released from the swelled TMMIPs. The kinetic results suggested that the TMMIPs possessed of a faster adsorption and recognition of 5-TCP than that of TMNIPs. The selective analysis demonstrated high affinity and selectivity of TMMIIPs towards 5-TCP over competitive phenolic compounds.更多还原