静电纺丝纳米纤维材料的制备及其对水中复合污染物的吸附研究

发布时间：2018-06-23 23:34

本文选题：静电纺丝 + 吸附　；参考：《南京大学》2017年硕士论文

【摘要】：近些年,水体中复合污染物的高效去除已经成为水环境治理过程中的研究热点。吸附法作为一种简单高效的水处理技术已经在废水治理领域得到广泛应用,所用吸附材料多为活性炭基吸附剂、矿物质吸附剂、生物吸附剂和人工合成高分子聚合物。相比较传统颗粒吸附材料,人工合成纤维状吸附材料具有韧性好、吸附速率高、易分离等优势,愈来愈引起学者们的关注。虽然很多学者对此开展了大量的研究,取得了一定的进展,但依然存在以下问题需要进一步研究解决:1)现有纤维材料制备方法多为分子纤维材料基体接枝功能基团的非均相反应模式,反应过程与产率难以调控,且制备的纤维吸附材料难以同时吸附重金属离子和小分子有机污染物;2)在复合污染体系中,不同污染物组分可能因吸附机理不同,在吸附材料之间存在着竞争-协同效应,而现有研究多针对单一组分体系吸附,并未能阐明复合污染体系中存在的竞争协同-效应;3)现有纤维吸附材料吸附方式多为固定床或静态吸附模式,吸附过程中纤维存在打结、填柱不均匀的缺陷,导致吸附过程中纤维与污染物接触不充分,影响吸附效果。因此研发新型双功能纤维吸附材料去除复合污染物,阐明复合污染体系中的竞争协同作用机制具有重要的理论价值与现实意义。基于上述研究背景,论文研究制备新型巯基功能化介孔纳米纤维与胺化聚丙烯腈/壳聚糖/聚乙烯醇纤维膜材料,以重金属离子Cu~(2+)与内分泌干扰物Cd~(2+)、BPA为目标污染物,深入开展吸附行为和机理研究:(1)利用均相聚合法和静电纺丝技术制备新型含巯基的介孔纤维吸附材料(MNF-SH),研究表明新型巯基功能化纳米纤维具有介孔结构和巯基功能基团,其比表面积为564.3 m2/g,孔容为0.495 cm3/g,其对Cu~(2+)最大平衡吸附量为5,431 mmol/g,吸附机理主要为巯基螯合作用;其对BPA的平衡吸附量为2.989 mmol/g,吸附机理主要为分子间作用力与氢键作用。且共存的硝酸根离子和氯离子会提高纤维对铜离子的吸附量,而降低对BPA的吸附;(2)以胺化反应、缩聚反应和静电纺丝技术制备了新型胺化聚丙烯腈/壳聚糖/聚乙烯醇纳米纤维膜(APAN/CS/PVA-NM),扫描电子显微镜和透射电子显微镜表征表明了纤维表面的大孔和介孔结构,胺化聚丙烯腈/壳聚糖/聚乙烯醇纳米纤维膜的平均孔径为1.5 μm。研究表明APAN/CS/PVA-NM对镉离子的吸附主要是功能化基团之间的相互作用(螯合作用),而对双酚A的吸附则不仅有功能化基团的相互作用(氢键作用),还有分子间作用力。可以采用膜滤运行模式,吸附去除双酚A和镉离子,过滤条件(pH值、进水浓度和流量)会对去除效果产生明显影响;(3)在Cu-BPA复合污染体系中,氢键作用和分子间作用力都对双酚A的吸附有重要作用,而铜离子的吸附则主要依靠螯合作用。虽然在铜离子和双酚A会竞争巯基吸附位点,但是APAN/CS/PVA-NM依然可以同时有效去除双酚A和铜离子,与此同时,通过分子间作用力吸附到APAN/CS/PVA-NM上的双酚A又可以螯合铜离子促进铜离子的吸附,连续吸附实验也表明双酚A类似桥联作用螯合铜离子;(4)在Cd-BPA复合污染体系中,双酚A的吸附主要是APAN氨基的氢键作用及CS/PVA的分子间作用力,镉离子的吸附主要是螯合作用。镉离子和双酚A在同时吸附和连续吸附时会竞争APAN/CS/PVA-NM氨基的吸附位点。并且同时存在高浓度双酚A会产生桥联作用促进镉离子的吸附。APAN/CS/PVA-NM对双酚A和镉离子的最佳吸附pH值为5.0,低于5.0,氢离子会与镉离子竞争吸附位点不利于镉离子的吸附,而高于5.0,则会使得酚羟基离子化影响双酚A的吸附。
[Abstract]:In recent years, the efficient removal of compound pollutants in water has become a hot topic in the process of water environment treatment. As a simple and efficient water treatment technology, adsorption method has been widely used in the field of wastewater treatment. The adsorbents used are active carbon based adsorbents, mineral adsorbents, biosorption and synthetic high grades. Compared with traditional particle adsorption materials, artificial synthetic fibrous adsorbents have the advantages of good toughness, high adsorption rate and easy separation, which have aroused the attention of scholars. Although many scholars have carried out a lot of research and made some progress, there still exist the following problems to be further studied and solved: 1) now Most of the preparation methods of fiber materials are non homogeneous reaction modes of functional groups grafted on the matrix of molecular fiber material, and the reaction process and yield are difficult to be regulated, and the prepared fiber adsorbents are difficult to adsorb heavy metal ions and small molecular organic pollutants at the same time. 2) in the compound pollution system, the adsorption mechanism of different pollutants may not be attributed to the adsorption mechanism. In the same way, there is a competitive synergistic effect between the adsorbents, and the existing research is mostly aimed at the adsorption of single component system, and the competition synergy in the composite pollution system is not clarified. 3) the adsorption mode of the existing fiber adsorbents is mostly fixed bed or static adsorption mode, and the fiber exists in the process of adsorption and the filling column is inhomogeneous. Therefore, it is of great theoretical and practical significance to develop a new dual functional fiber adsorption material to remove compound pollutants and clarify the mechanism of competition synergy in the compound pollution system. Functionalized mesoporous nanofibers and amamination of Polyacrylonitrile / chitosan / polyvinyl alcohol fiber membrane materials, with heavy metal ions Cu~ (2+) and endocrine disruptors Cd~ (2+) and BPA as the target pollutants, have carried out a thorough study of adsorption behavior and mechanism. (1) a new mesoporous fiber adsorption material containing sulfhydryl group (MN) was prepared by homogeneous polymerization and electrostatic spinning technology (MN) F-SH), the study shows that the new mercapto functionalized nanofibers have mesoporous structure and sulfhydryl functional groups. The specific surface area of the nanofibers is 564.3 m2/g, Kong Rong is 0.495 cm3/g, and the maximum equilibrium adsorption capacity for Cu~ (2+) is 5431 mmol/g. The adsorption mechanism is mainly mercapto chelation, and the equilibrium adsorption capacity for BPA is 2.989 mmol/g, and the adsorption mechanism is mainly divided into two parts. The adsorption of copper ions and the adsorption of copper ions were increased by the coexisting nitrate and chlorine ions, and the adsorption of BPA was reduced. (2) a new amine polyacrylonitrile / chitosan / polyvinyl alcohol nanofiber membrane (APAN/CS/PVA-NM) was prepared by amination, polycondensation and electrospinning. Scanning electron microscopy and scanning electron microscopy were used. The transmission electron microscope (TEM) characterizing the large pore and mesoporous structure of the fiber surface, the average pore size of the amidated polyacrylonitrile / chitosan / polyvinyl alcohol nanofiber film is 1.5 m.. The study shows that the adsorption of APAN/CS/PVA-NM on the cadmium ion is mainly the interaction between the functional groups (chelating), while the adsorption of bisphenol A is not only active. The interaction of the energetic groups (hydrogen bonding) and intermolecular force. The membrane filtration operation mode can be used to remove bisphenol A and Cd ions. The filtration conditions (pH value, influent concentration and flow) will have a significant effect on the removal efficiency. (3) the adsorption of hydrogen bond and intermolecular force on the adsorption of bisphenol A in the Cu-BPA composite pollution system The adsorption of copper ions is mainly dependent on chelation. Although the copper ion and bisphenol A will compete for the sulfhydryl adsorption site, APAN/CS/PVA-NM can still effectively remove bisphenol A and copper ions simultaneously. At the same time, the bisphenol A adsorbed on APAN/CS/ PVA-NM by intermolecular force can chelate copper ions to promote copper ions. The adsorption of ions and continuous adsorption experiments also show that bisphenol A is similar to bridging chelating copper ions; (4) in the Cd-BPA composite pollution system, the adsorption of bisphenol A is mainly the hydrogen bond of APAN amino and the intermolecular force of CS/PVA, and the adsorption of cadmium ions is mainly chelation. For the adsorption site of APAN/CS/PVA-NM amino group, and the presence of high concentration of bisphenol A produces bridging action to promote the adsorption of cadmium ions, and the best adsorption pH value of.APAN/CS/PVA-NM for bisphenol A and cadmium ions is 5, which is lower than 5. Hydrogen ions will compete with cadmium ions and disadvantageous to the adsorption of cadmium ions, while higher than 5 will lead to phenol hydroxyl groups. The crystallization affects the adsorption of bisphenol A.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ342.86;X703

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