【作者】 陈浩；

【导师】 崔立莉； 叶正芳；

【作者基本信息】 河北建筑工程学院 ， 工程硕士（专业学位）， 2020， 硕士

【摘要】 随着工业化水平的提高和经济飞速增长,环境污染问题也日益严重。TCE作为典型的土壤中挥发性有机污染物和TNT作为炸药废水的主要污染成分,对土壤和地下水污染都成为环境领域关注的焦点。由于两种物质的溶解度均较低,且难生物降解,故在自然环境中可以长期存在。目前对两种污染物质的处理方式较为简单,主要集中在物理吸附和高级氧化方面,存在成本较高,易于形成二次污染等缺点,而吸附法则经济高效,在国内外得以广泛应用。本研究在TNT分子印迹聚合物合成和TCE土壤修复两个方面展开了研究工作。在TNT分子印迹聚合物合成方面,通过水相沉淀聚合法合成了具有较高选择性、较好分散性、且可快速吸附的TNT分子印迹聚合物和TNT磁性纳米分子印迹聚合物。以UV-vis、FTIR、ESEM、BET、TGA对其进行表征。此外,对聚合物对TNT的吸附动力学、吸附热力学和选择性吸附进行了研究。首先通过水相沉淀聚合法,以TNT为模板分子,AM为功能单体,EGDMA为交联剂,合成了新型水相印迹聚合物和水相非印迹聚合物。研究结果表明,该法可成功合成具有稳定结构的选择特异性分子印迹聚合物。该聚合物可在200min内达到吸附平衡。在5 mmol/L的TNT乙腈溶液中,聚合物的平衡吸附量为263 mmol/kg。Scatchard拟合分析表明,富电子的功能单体丙烯酰胺和缺电子的TNT的苯环具有较强的电荷转移作用,从而可以形成比较稳定的复合物。此外,交联剂EGDMA有一很明显的特点可以延缓聚合物反应的相分离时间,从而可以合成高质量的印迹材料。与水相非印迹聚合物相比,水相印迹聚合物对TNT展现了更高的吸附速率、更大的吸附容量以及更高的选择性。与结构类似物DNT相比,对TNT的选择特异性主要是由于CMIP表面的印迹孔穴导致。Fe₃O₄材料具有刚性强、不膨胀、容易在表面进行修饰和在外加磁场条件下可以快速进行固液分离等特点,因此Fe₃O₄颗粒特别适合用于制备分子印迹材料的核芯。本文在对纳米Fe₃O₄颗粒表面进行修饰后,利用两步水相沉淀聚合法,在其表面合成了具有选择性吸附位点的纳米磁性分子印迹聚合物,以实现快速吸附分离的目的。研究结果表明,加入适量的十二烷基苯磺酸钠,可以制备出粒径小、且分散均匀的磁性分子印迹聚合物。加入带正电的功能单体,可以改善聚合物对TNT的吸附量。与非磁性分子印迹聚合物相比,磁性分子印迹聚合物的吸附量提高了38 mmol/kg,表明Fe₃O₄颗粒合成聚合物能够进一步有效提高分子印迹聚合物的特异吸附容量。这主要是因为上述材料内部的识别位点不能被有效利用所致。该磁性纳米TNT分子印迹聚合物具有粒径分布均匀、较大比表面积、较高选择性、较好分散性,且可快速吸附、分离的特点。在TCE污染土壤研究中,本文采用高温氧化法（375℃、600℃）和较低氧化性的次氯酸钠氧化法来处理土壤,研究了不同的土壤组分（软碳、硬碳、矿物质）对TCE吸附过程和机理。基于静态吸附实验对土壤吸附TCE的影响因素进行研究。通过高温氧化法和次氯酸钠氧化法来处理土壤,以有机质含量为0.96%的土样及经375℃、600℃、次氯酸钠以及联合氧化法（600℃+次氯酸钠）处理的土样作为吸附剂,考察了各种土样吸附TCE的吸附动力学和吸附热力学,研究了土壤中软碳、硬碳、矿物质含量,TCE初始浓度和钙离子强度对吸附作用的影响。研究结果表明,土壤对TCE的吸附分为快速吸附、慢速吸附和平衡3个阶段,并在30 h左右达到吸附平衡,TCE在快速吸附阶段的吸附量就达到了总吸附量的70%左右。通过吸附动力学和热力学研究发现,该吸附过程符合准二级动力学方程（R2>98%）。Freundlich模型能较好拟合TCE在土壤中的吸附过程（R2>93%）,且土壤对TCE的吸附以物理吸附为主。对土壤中的软碳、硬碳和矿物质三种组分研究发现,土样对TCE吸附是有机质和矿物质共同作用的结果。其中,有机质中的硬碳对吸附TCE起主要作用,其吸附贡献率>60%,而矿物质对TCE的吸附也起到了一定的作用。TCE浓度的升高可以提高矿物质的吸附贡献率。离子强度(Ca²⁺)的增加显著降低了土壤各组分对TCE的吸附效果。更多还原

【Abstract】 With the improvement of industrialization and rapid economic growth,the problem of environmental pollution has also become increasingly serious.TCE as a typical soil volatile organic pollutant and TNT as the main pollution component of explosive wastewater,soil and groundwater pollution has become the focus of environmental field.Due to the low solubility of the two substances and the difficulty of biodegradation,they can exist in the natural environment for a long time.At present,the treatment methods for the two pollutants are relatively simple,mainly focused on physical adsorption and advanced oxidation,with high cost,easy to form secondary pollution and other shortcomings.However,the adsorption method is economical and efficient,and has been widely used at home and abroad.In this study,TNT molecularly imprinted polymer synthesis and TCE soil remediation were studied.In the synthesis aspect of TNT molecularly imprinted polymers,TNT molecularly imprinted polymer and TNT magnetic nano-molecularly imprinted polymer with high selectivity,good dispersibility and rapid adsorption were synthesized by water phase precipitation polymerization method.It was characterized by UV-vis,FTIR,ESEM,BET,and TGA.In addition,the adsorption kinetics,thermodynamics and selective adsorption of TNT on polymers were studied.Firstly,a novel water-phase imprinted polymer and water-phase non-imprinted polymer were synthesized by water phase precipitation polymerization method,with TNT as template molecule,am as functional monomer and EGDMA as crosslinking agent.The results show that selective imprinted polymers with stable structure can be synthesized by this method.The polymer can reach adsorption equilibrium within 200min.In 5 mmol/L TNT acetonitrile solution,the equilibrium adsorption capacity of the polymer is 263 mmol/kg.Scatchard fitting analysis shows that the electron-rich functional monomer acrylamide and the electron-deficient TNT benzene ring have a strong charge transfer effect,which can form a relatively stable complex.In addition,the cross-linking agent EGDMA has the obvious feature of delaying the phase separation time of the polymer reaction,so that high-quality imprinted materials can be synthesized.Compared with water-phase non-imprinted polymers,water-phase imprinted polymers exhibit higher adsorption rate,larger adsorption capacity and higher selectivity for TNT.Compared with the structural analog DNT,the specificity of selection for TNT is mainly due to the imprinted holes on the surface of CMIP.Fe₃O₄material has the characteristics of strong rigidity,non-expansion,easy surface modification and rapid solid-liquid separation under the condition of external magnetic field.Therefore,Fe₃O₄particles are particularly suitable for preparing the core of molecularly imprinted materials.In this paper,after modifying the surface of nano-Fe₃O₄particles,a two-step aqueous precipitation polymerization method was used to synthesize nano-magnetic molecularly imprinted polymers with selective adsorption sites on the surface,so as to achieve rapid adsorption and separation.The results show that magnetic molecularly imprinted polymers with small particle size and uniform dispersion can be prepared by adding appropriate amount of sodium dodecylbenzene sulfonate.The amount of TNT adsorbed by the polymer can be improved by adding the functional monomer with positive charge.Compared with the non-magnetic molecularly imprinted polymer,the adsorption capacity of the magnetic molecularly imprinted polymers is increased by 38 mmol/kg,indicating that Fe₃O₄particle synthetic polymers can further effectively improve the specific adsorption capacity of molecularly imprinted polymers.This is mainly because the recognition sites in the above materials can not be used effectively.The magnetic nano-TNT molecularly imprinted polymer has the characteristics of uniform particle size distribution,larger specific surface area,higher selectivity,better dispersion,and can be quickly adsorbed and separated.In the study of TCE contaminated soil,high temperature oxidation（375℃,600℃）and low oxidation sodium hypochlorite oxidation were used to treat the soil,and the adsorption process and mechanism of TCE by different soil components（soft carbon,hard carbon,and minerals）were studied.Based on the static adsorption experiment,the influencing factors of TCE adsorption on soil were studied.Through high temperature oxidation and sodium hypochlorite oxidation method to deal with the soil,with organic matter content is0.96%of the soil samples and 375℃,600℃,sodium hypochlorite and combined oxidation（600℃+sodium hypochlorite）of soil samples as adsorbents,the various soil adsorption of TCE adsorption kinetics and adsorption thermodynamics,the content of soft soil carbon,hard carbon,and minerals in the soil,the initial concentration of TCE and the strength of calcium ion on the adsorption were studied.The results show that the soil adsorption of TCE on soil can be divided into three stages:fast adsorption,slow adsorption and equilibrium.The adsorption equilibrium of TCE can be achieved in about 30 hours,and the adsorption capacity of TCE in the fast adsorption stage can reach about 70%of the total adsorption capacity.According to the adsorption kinetics and thermodynamics,it is found that the adsorption process conforms to the quasi-second-order kinetic equation（R²>98%）.And the soil adsorption of TCE is mainly physical adsorption.According to the study of soft carbon,hard carbon and minerals in soil,it is found that the adsorption of TCE by soil samples is the result of of the combined action of organic matter and minerals.Among them,the hard carbon in organic matter plays a major role in the adsorption of TCE,and the contribution rate of adsorption is more than 60%,while the minerals also play a certain role in the adsorption of TCE.The increase of TCE concentration can increase the contribution rate of mineral adsorption.The increase of ionic strength(Ca²⁺)significantly reduced the adsorption effect of TCE by various soil components.更多还原