纳米金属氧化物基杂化材料的制备及其对重金属离子的去除研究

发布时间：2018-03-04 08:05

本文选题：聚乙烯醇　切入点：粉煤灰　出处：《兰州大学》2015年硕士论文　论文类型：学位论文

【摘要】：人类的生产及生活活动产生大量含有重金属的废水,但是由于某些原因这些废水未经处理或处理未达标就排向自然环境,导致水体、土壤等受到不同程度的污染。由此引发的水污染问题已严重危害到经济的可持续发展和公众身体健康,因而有效的水污染处理技术的开发和研究受到了国内外学者的广泛关注。吸附法由于吸附材料来源广泛、价格低廉、操作过程不需要复杂装置及添加额外化学物质等优点,被越来越多地应用在重金属水污染处理领域。本论文设计并合成了一系列吸附量大、吸附速率快、去除效率高、对某种金属离子具有选择识别性、重复利用率高且.价格低廉、制备简单的新型杂化吸附材料。并运用扫描电镜(SEM)、X-射线衍射(XRD)、傅立叶红外光谱(FT-IR)等技术对新型吸附剂形貌、晶形、表面功能团等进行了表征。考察了初始浓度、溶液pH值、共存离子等因素对杂化材料去除污水中重金属离子性能的影响。同时,运用各种吸附等温线模型、动力学模型对吸附平衡数据进行模拟,初步探讨了吸附过程的机理,速度控制步骤等。本学位论文的主要研究内容如下：1.聚乙烯醇(PVA)包囊Mn02纳米棒的制备及其对水中Hg(Ⅱ)的吸附研究PVA具有低价,生物相容性好,机械强度大等优点,且由于具有大量的羟基,故可用于对重金属离子的锚定和键合。本章采用水热法制备了结构较为均一的MnO2纳米棒。然后以硼酸-CaCl2为成型液制备了PVA/MnO2内米棒杂化小球,研究了影响PVA/MnO2纳米棒杂化小球吸附Hg2+的主要因素。结果表明：PVA/MnO2纳米棒杂化小球具有大孔三维网状结构,这种大孔网状结构更有利于金属离子在其内部的扩散和吸附。在吸附过程中,PVA和MnO2纳米棒呈现出种协同增强效应,吸附效率明显高于单一PVA小球。动力学试验显示,PVA/MnO2纳米棒杂化小球对溶液中的Hg2+具有较快的吸附速率。同时PVA/MnO2纳米棒杂化小球具有明显的选择性,可从含多种金属离子的溶液中选择性的去除Hg2+PVA中加入Mn02纳米棒使新型吸附剂的pH适用范围更宽广,在pH值为3-7内都具有较好的吸附性能。另外PVA/MnO2小球结构也使得分离过程变得更为简单和有效,更适用于工业生产。在此基础上,采用Langmuir 和 Freundlic h等温线；准一级反应和准二级反应方程分析了PVA/MnO2纳米棒杂化小球的吸附过程。2.纳米MnO2修饰粉煤灰的制备及其去除Pb(Ⅱ)和Hg(Ⅱ)的研究粉煤灰是煤燃烧的主要副产物,其中有大量的铝、硅等金属氧化物,可以与重金属离子产生化学键合作用。粉煤灰具有多孔结构,比表面积大,有望成为廉价高效的吸附剂材料。本文将过硫酸铵和硫酸锰溶解后加入粉煤灰,一锅法制备MnO2-粉煤灰杂化材料(FA@nM)。采用一锅法具有收率较高,操作简单等优点。详细研究了影响FA@nM杂化材料对Hg2+和Pb2+吸附的因素。通过多种表征分析了所制备FA@nM杂化材料的表观形貌、存在的官能团、形成的晶形结构、比表面积等。结果表明,MnO2在FA表面的负载较为均一,表面结构规整；FA@nM杂化材料的最大比表面积可达677 m2/g,负载后的FA极大的增加了对Hg2+和Pb2+的吸附能力,分别为41和53.2 mg/g。FA@nM杂化材料可以在较宽的pH范围内有效去除Hg2+和Pb2+离子。Langmuir等温线模型对FA@nM杂化材料吸附Hg2+和Pb2+具有较好的拟合性,表明Hg2+和Pb2+ 在FA@nM表面形成了单分子层吸附。动力学试验显示FA@nM杂化材料对Pb2+的吸附速率明显快于Hg2+,表面吸附和粒子内扩散参与到吸附过程当中。因此,FA@nM杂化材料作为一种新型复合材料有望应用于工业污水中重金属离子的去除。3.生物大分子单宁酸(TA)修饰粉煤灰的制备及其对Pb(Ⅱ)的吸附性能研究单宁酸(TA)具有大量的酚羟基,易溶于水,与重金属离子锚定和键合形成不溶性复合物。本章主要将粉煤灰、单宁酸、钡盐和磷酸盐反应制得FA/TA/BaP杂化型材料,在采用SEM对材料形貌进行表征,XRD、FT-IR的分析结果表明粉煤灰、单宁酸及钡盐和磷酸盐发生了复合交联反应,本文以Pb2+为目标吸附物。试验表明：FA/TA/BaP杂化材料对Pb2+的最大吸附容量为216.1 mg/g,远远大于单一粉煤灰及单宁酸的吸附量。pH研究显示,FA/TA/BaP杂化材料在较宽pH值范围内都具有较好的吸附行为。研究显示,FA/TA/BaP杂化材料对Pb2+的吸附符合Freundlich等温线模型和准二级动力学模型,FA/TA/BaP杂化材料对Pb2+的吸附和解吸循环试验进一步证实了材料具有优异的可重复使用性和稳定性。由此可见,A/TA/BaP杂化材料作为一种新型有效的杂化材料可望应用于废水中Pb2+离子的去除及富集。
[Abstract]:The waste water containing heavy metals production and life activities of human being, but for some reason the wastewater untreated or treated with substandard discharge to the natural environment, resulting in water, soil and other polluted. The water pollution problem caused by this has serious harm to the sustainable development of the economy and the health of the public, thus the research and development of water pollution and effective treatment technology has received extensive attention of scholars at home and abroad. Due to the adsorption of wide material source, low price of adsorption process does not require complicated device and add additional chemicals and other advantages, is increasingly used in the field of heavy metal pollution processing. This paper presents the design and synthesis of a series of the adsorption capacity, adsorption speed, high removal efficiency, with selective recognition of certain metal ions, high recycling rate and low price, simple preparation A new hybrid adsorbent. By using scanning electron microscopy (SEM), X- ray diffraction (XRD), infrared spectroscopy (FT-IR) crystal Fu Liye technology of the new adsorbent, morphology, surface functional groups were investigated. The effects of initial concentration, pH value of solution, influence of coexisting ions on the heavy metal removal performance of sewage in the hybrid materials. At the same time, the use of various adsorption isotherm model, dynamic model simulation of adsorption equilibrium data, discussed the mechanism of the process, the rate controlling step. The main research contents of this thesis are as follows: 1. polyvinyl alcohol (PVA) preparation of encapsulated Mn02 nanorods and Hg on the adsorption of water (II) study on PVA with low price, good biocompatibility, mechanical strength and other advantages, and has a large number of hydroxyl groups, so that it can be used for heavy metal ions on anchoring and bonding. This chapter was prepared by hydrothermal method with structure For the uniform MnO2 nanorods. Then there is PVA/MnO2 -CaCl2 with boric acid to prepare hybrid rod ball forming fluid system, studied the main factors affecting the adsorption of Hg2+ PVA/MnO2 nanorods hybrid ball. The results show that the PVA/MnO2 nanorods hybrid beads with large pore 3D mesh structure, more conducive to the macroreticular structure diffusion and adsorption of metal ions in the interior. In the process of adsorption, PVA and MnO2 nanorods showing a synergistic effect, the adsorption efficiency was significantly higher than that of single PVA ball. The dynamic test showed that, PVA/MnO2 nanorods hybrid beads with higher adsorption rate of Hg2+ in the solution. At the same time PVA/MnO2 nanorods hybrid ball has obvious selectivity, adding Mn02 nanorods Hg2+PVA selectively removal from solution containing a variety of metal ions in the new adsorbent pH scope is wider, the pH value is 3-7 in is Good adsorption properties. In addition PVA/MnO2 ball structure also makes the separation process simpler and more effective, more suitable for industrial production. On this basis, using Langmuir and Freundlic h isotherm; first-order reaction and quasi two order reaction equation analysis of the preparation of PVA/MnO2 nanorods hybrid small ball adsorption process of.2. modified nano MnO2 powder ash and the removal of Pb (II) and Hg (II) of fly ash is the main by-product of coal combustion, which has a large number of aluminum, silicon and other metal oxides, can produce chemical bonds with metal ions. Effect of fly ash has porous structure, large surface area, is expected to become a cheap and efficient adsorbent material. This paper will have. Ammonium sulfate and manganese sulfate solution after adding fly ash, fly ash and preparation of MnO2- hybrid materials (FA@nM). One pot method has higher yield by one pot method, simple operation and so on. A detailed study of the influence of F A@nM hybrid materials of Hg2+ and Pb2+ adsorption. Through a variety of characterization of the synthesized FA@nM hybrid material surface morphology, the presence of functional groups, crystal structure formation, the specific surface area. The results show that MnO2 is in the load on the surface of FA uniform and orderly surface structure; FA @nM hybrid material maximum ratio the surface area of up to 677 m2/g, load FA greatly increased the adsorption capacity of Hg2+ and Pb2+, respectively, 41 and 53.2 mg/g.FA@nM hybrid materials can be in a wide range of pH can effectively remove Hg2+ and Pb2+ ion.Langmuir isotherm model has better fitting of FA@nM hybrid materials for adsorption of Hg2+ and Pb2+, and that Hg2+ Pb2+ formed a single molecular layer adsorption on the surface of FA@nM. The dynamic test showed that the adsorption rate of FA@nM hybrid material of Pb2+ was faster than that of Hg2+. The adsorption and diffusion in the particle surface involved in the adsorption process. Therefore, FA@n M hybrid materials as a kind of new composite material is expected to be applied to the heavy metal ions in industrial wastewater.3. removal of biological macromolecules of tannic acid (TA) modified fly ash and preparation of Pb (II) study on the adsorption of tannic acid (TA) has a large number of phenolic hydroxyl groups, soluble in water and heavy metal ions and anchor the bond formation of insoluble complexes. This chapter will fly ash, tannic acid, barium salt and phosphate was prepared by the reaction of FA/TA/BaP hybrid materials, the materials were characterized by SEM, the morphology of XRD, the results of FT-IR analysis showed that fly ash, the composite crosslinking reaction of tannic acid and barium salt and phosphate, based on Pb2+ as the goal of adsorption. The results showed that the maximum adsorption capacity of FA/TA/BaP hybrid material of Pb2+ is 216.1 mg/g, study on the adsorption capacity of.PH is much larger than a single fly ash and tannic acid showed that FA/TA/BaP hybrid materials in a wide range of pH value Have a good adsorption behavior. The study showed that the adsorption of Pb2+ FA/TA/BaP hybrid material with the Freundlich isotherm model and pseudo two order kinetics model, adsorption and desorption cycle test of FA/TA/BaP hybrid material of Pb2+ further confirmed that the material has excellent reuse and stability. Thus, A/TA/BaP hybrid materials as a kind of new and efficient the hybrid materials could be applied to Pb2+ ion removal and enrichment.

【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;TB383.1

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