离子印迹水凝胶的制备及其对重金属的吸附研究

发布时间：2018-07-15 10:11

【摘要】：改革开放以来,我国经济迅猛发展,工业化和城镇化速度加快。与此同时,产生了各种各样的重金属污染,严重威胁了人们的生存和健康。在各种重金属废水治理方法中,吸附法由于其处理效率高、吸附剂来源丰富、价格低廉、无二次污染而被广泛应用于对重金属废水的处理。本课题的研究目的是制备一种对水体中重金属具有选择性吸附和深度去除能力的新型吸附材料,为重金属废水治理研发新的材料。本文利用低温辐射技术,合成了共聚物水凝胶——聚(聚乙烯亚胺/2-丙烯酸羟乙酯)[p(PEI/HEA)],对制得的水凝胶进行了铜离子印迹,得到铜离子印迹水凝胶Cu(Ⅱ)-p(PEI/HEA),通过一系列表征方法：SEM、EI、FTIR、TGA和XPS,对水凝胶微观形貌、元素组成、基团种类、热稳定性及元素形态进行了分析,研究了p(PEI/HEA)和Cu(Ⅱ)-p(PEI/HEA)对Cu(Ⅱ)、Pb(Ⅱ)、Cd(Ⅱ)、Ni(Ⅱ)四种重金属离子的吸附性能,探讨了pH值、温度、重金属初始浓度、竞争吸附等对吸附过程的影响,运用TGA和XPS分析,解析了水凝胶对重金属的吸附机理,并且探讨了水凝胶的脱附再生特性,具体结论如下：1.在-78℃条件下,用60Co-γ射线对单体(PEI和HEA)进行辐射,合成了聚合物水凝胶p(PEI/HEA)。在此基础上,采用离子印迹技术,对合成的水凝胶进行铜离子印迹,制备了印迹水凝胶Cu(Ⅱ)-p(PEI/HEA);2.p(PEI/HEA)水凝胶具有多孔网状结构,孔道不规格,孔径范围为10-20μm。铜离子印迹过程使水凝胶孔道尺寸略有增大,且表面粗糙度显著增大；组分PEI稳定存在于水凝胶网络结构中;p(PEI/HEA)和Cu(Ⅱ)-p(PEI/HEA)均是HEA和PEI的共聚产物,具有胺基和羟基；水凝胶p(PEI/HEA)和Cu(Ⅱ)-p(PEI/HEA)的热稳定性均高于纯HEA单体但低于纯PEI；水凝胶Cu(Ⅱ)-p(PEI/HEA)的各组成元素不是均匀分布在其表面及内部的,铜离子可成功地被水凝胶吸附到其表面及内部；3.不同单体配比的p(PEI/HEA)水凝胶的溶胀性能随水体积分数的增大以及PEI含量的增多而逐渐增大。溶胀率在2.7～3.4之间,当PEI摩尔含量为25%,水所占体积为8/10时,溶胀率达到最大；其对重金属离子的吸附量随着单体组分中PEI所占的摩尔分数的增大以及体系水分的减少而显著升高。PEI摩尔含量为25%,且水所占体积为6/10时,对重金属具有最优的吸附效果；4.铜离子印迹后的水凝胶Cu(Ⅱ)-p(PEI/HEA)对铜离子的吸附量显著提高,且远远高于未印迹的水凝胶p(PEI/HEA);5.水凝胶p(PEI/HEA)和Cu(Ⅱ)-p(PEI/HEA)的吸附量随着体系pH值的逐渐升高而增大,在pH为5.5时,达到最大；且均受温度的影响,提高体系温度,有利于吸附过程的进行。吸附过程是自发的熵增过程,吸附反应是吸热反应；6.水凝胶p(PEI/HEA)和Cu(Ⅱ)-p(PEI/HEA)的等温吸附过程属于Langmuir单分子层优惠吸附；且其动力学吸附过程符合准二级动力学方程,吸附限速步骤是化学吸附过程；7.Cu(Ⅱ)-p(PEI/HEA)对铜离子的吸附量受溶液中碱金属含量的影响,但M/Cu摩尔比大于5之后,吸附量趋于平衡,不再降低；水凝胶Cu(Ⅱ)-p(PEI/HEA)对重金属的竞争优先性为Cu(Ⅱ)Pb(Ⅱ)Cd(Ⅱ)Ni(Ⅱ),在Cu(Ⅱ)/Cd(Ⅱ)、Cu(Ⅱ)/Cd(Ⅱ)和Cu(Ⅱ)/Ni(Ⅱ)的混合溶液中,印迹凝胶对铜离子的选择性系数分别为55.09、107.47、63.12,远高于未印迹凝胶,印迹作用提高了水凝胶对铜离子的选择性；8.Cu(Ⅱ)-p(PEI/HEA)水凝胶通过化学吸附作用吸附水中铜离子,具体机理为含氮基团(伯胺、仲胺、叔胺)和含氧基团(羟基、羰基)与铜离子之间的络合作用；9.最高的脱附效率在EDTA溶液浓度为0.1 mol/L时达到,为93.2%。水凝胶Cu(Ⅱ)-p(PEI/HEA)对铜离子的吸附量随着吸附-脱附循环次数的增多而有所下降但经过4次吸附-脱附循环之后对铜离子的吸附量仍保持在相对较高的水平,为初始吸附量的85%。
[Abstract]:Since the reform and opening up, China's economy has developed rapidly and industrialization and urbanization speed up. At the same time, a variety of heavy metal pollution has been produced, which seriously threaten people's survival and health. In the treatment of various heavy metal wastewater, adsorption method has high efficiency, rich adsorbents, low price, and no two pollution. It is widely used in the treatment of heavy metal wastewater. The purpose of this study is to prepare a new type of adsorbents for the selective adsorption and depth removal of heavy metals in the water body, and to develop new materials for the treatment of heavy metal wastewater. In this paper, a copolymer hydrogel, poly (polyethyleneimine /2-), is synthesized by using low temperature radiation technology. Hydroxyethyl acrylate) [p (PEI/HEA)], copper ion imprinting was carried out on the prepared hydrogels, and copper ion imprinted hydrogel Cu (II) -p (PEI/HEA) was obtained. Through a series of characterization methods, SEM, EI, FTIR, TGA and XPS, the micromorphology, element composition, group type, thermal stability and elemental morphology of the hydrogel were analyzed. P (PEI/HEA) and -p were studied. II) the adsorption properties of -p (PEI/HEA) on four kinds of heavy metal ions of Cu (II), Pb (II), Cd (II), Ni (II), and the influence of pH value, temperature, initial concentration of heavy metal and competitive adsorption on the adsorption process. The adsorption mechanism of hydrogels on heavy metals was analyzed by TGA and XPS analysis, and the desorption regeneration characteristics of hydrogels were discussed, and the specific conclusions were discussed. 1. under the condition of -78 C, the monomer (PEI and HEA) was irradiated with 60Co- gamma ray, and polymer hydrogel P (PEI/HEA) was synthesized. On this basis, the synthetic hydrogels were imprinted with copper ion imprinting by ion imprinting technology, and the imprinted hydrogel Cu (II) -p (PEI/HEA) was prepared. The 2.p (PEI/HEA) hydrogel had porous network structure and irregular channel. Lattice, the pore size of 10-20 M. copper ion imprinting process makes the pore size of the hydrogel slightly increased and the surface roughness increases significantly; the component PEI is stable in the hydrogel network structure; P (PEI/HEA) and Cu (II) -p (PEI/HEA) are all the copolymers of HEA and PEI, with the amino groups and hydroxyl groups; hydrogel P (PEI/HEA) and Cu (II) The thermal stability is higher than pure HEA monomer but lower than pure PEI; the composition elements of Cu (II) -p (PEI/HEA) of hydrogel are not evenly distributed on its surface and inside. Copper ions can be adsorbed on the surface and inside of the hydrogel successfully. 3. the swelling properties of P (PEI/HEA) water gel with different monomer ratio increase with the increase of water volume fraction and PEI content The swelling rate is between 2.7 and 3.4. When the PEI molar content is 25% and the volume of the water is 8/10, the swelling rate reaches the maximum. The adsorption capacity of the heavy metal ions increases with the increase of the molar fraction of PEI in the monomer component and the decrease of the system water, and the content of.PEI mole is 25%, and the water occupying body. When the product is 6/10, it has the best adsorption effect on heavy metals, and the adsorption capacity of Cu (II) -p (PEI/HEA) on copper ion after 4. copper ion imprinting is significantly higher than that of P (PEI/HEA), which is far higher than that of the non imprinted hydrogel. The adsorption capacity of the 5. hydrogel P (PEI/HEA) and Cu (II) -p (PEI /HEA) increases with the gradual increase of the system values, which is 5.5. The adsorption process is the spontaneous entropy increase process and the adsorption reaction is endothermic reaction; the isothermal adsorption process of 6. hydrogel P (PEI/HEA) and Cu (II) -p (PEI/HEA) belongs to the Langmuir single molecular layer preferential adsorption, and the kinetic adsorption process conforms to the adsorption process. The adsorption rate of 7.Cu (II) -p (PEI/HEA) is influenced by the content of alkali metals in the solution, but the adsorption amount of M/Cu (II) -p (II) -p (PEI/HEA) is Cu (II) Pb (II) Cd (II) Ni (II) Cd (II) Ni, but the adsorption amount of 7.Cu (II) -p (II) is affected by the alkali metal content in the solution, but after the molar ratio is greater than that of the -p (PEI/HEA). Second, in the mixed solution of Cu (II) /Cd (II), Cu (II) /Cd (II) and Cu (II) /Ni (II), the selectivity coefficient of the imprinted gel to copper ions is 55.09107.47,63.12, respectively, which is much higher than that of the non imprinted gel. The selectivity of the hydrogel improves the selectivity of the copper ion, and 8.Cu (II) -p (PEI/HEA) hydrogel adsorbs copper in water by chemical adsorption. The specific mechanism is the complexation of nitrogen groups (primary amines, secondary amines, tertiary amines) and oxygen containing groups (hydroxyl, carbonyl) and copper ions; 9. the highest desorption efficiency is reached when the concentration of EDTA solution is 0.1 mol/L, and the adsorption amount of Cu (II) -p (PEI/HEA) on the copper separation of 93.2%. hydrogel decreases with the increase of the number of adsorption desorption cycles. However, after 4 cycles of adsorption desorption, the adsorption capacity of copper ions is still relatively high, which is 85%. of initial adsorption capacity.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

【共引文献】