【作者】 鲁菲菲；

【导师】 尹业平；

【作者基本信息】 华中农业大学 ， 应用化学， 2010， 硕士

【摘要】 天然多糖大分子具有大量的活性基团(如-OH、-NH2等),并且来源丰富,安全无毒,可生物降解,自身或者通过改性可以制备具有一定吸附量的吸附剂。魔芋葡甘聚糖(KGM)是同淀粉、纤维素、壳聚糖类似的天然多糖大分子,由于其自身的特性,在食品、化工等领域已经有较广泛的应用,是一种具有环保效应的天然材料。本文对魔芋葡甘聚糖进行交联、醚化和胺化改性,制备了重金属吸附剂—ACKGM,利用红外光谱、扫描电镜、X-衍射仪表征了各个产物的结构和表面形貌等性质,探讨了ACKGM对Cu(Ⅱ)、Ni(Ⅱ)、Cr(Ⅵ)的吸附行为。(1)探讨了交联、醚化、胺化反应的条件。交联魔芋葡甘聚糖(CKGM)的制备条件：溶剂异丙醇的浓度为15%, NaOH与KGM的摩尔比为1：2,环氧氯丙烷与KGM的摩尔比为1：1,反应温度50℃,反应时间为6h,制备了沉降积为53.5的CKGM;3-氯-2-羟基丙基交联魔芋葡甘聚糖醚(CHKGM)的制备条件：CKGM的含水率为11～13%,催化剂HClO4与CKGM的摩尔比为0.03：1,80℃,反应8h,制备了Cl含量为0.0503、Cl的取代度(DSCl)为0.2642的CHKGM;当胺化剂中的(-NH2)与CHKGM的摩尔比为4：1,60℃,反应时间为4h,分别以乙二胺、二乙烯三胺、三乙烯四胺为胺化剂制备了三种交联氨基魔芋葡甘聚糖EACKGM、DACKGM和TACKGM,它们的氮取代度(DSN)分别为0.0522、0.07695、0.1228。(2)将EACKGM、DACKGM和TACKGM应用于对Cu(Ⅱ)、Ni(Ⅱ)、Cr(Ⅵ)吸附研究,其吸附能力顺序为：TACKGM> DACKGM> EACKGM。讨论了溶液的pH值、TACKGM用量、离子初始浓度、振荡时间、温度等因素对TACKGM的吸附性能的影响。30℃时TACKGM对Cu(Ⅱ)、Ni(Ⅱ)、Cr(Ⅵ)的饱和吸附量分别为18.38mg·g-1、5.173 mg·g-1、21.51mg·g-1。(3)研究了TACKGM吸附Cu(Ⅱ)、Ni(Ⅱ)、Cr(Ⅵ)的热力学和动力学行为,为其开发与应用提供理论依据。TACKGM对Cu(Ⅱ)、Ni(Ⅱ)的等温吸附过程可以用Langmuir模型描述,TACKGM对Cr(Ⅵ)的等温吸附过程既可以用Langmuir模型描述也可以用Freundlish模型描述。通过对等温吸附数据的拟合,得到相应的热力学参数,TACKGM对Cu(Ⅱ)、Ni(Ⅱ)的吸附过程是一个自发的、吸热的、熵增加的过程,而对Cr(Ⅵ)的吸附过程是一个自发的、放热的、熵减小的过程；吸附动力学研究表明,与伪一级动力学模型相比,伪二级动力学模型更适合描述TACKGM对各种离子的吸附过程。用伪二级动力学模型拟合所得到的平衡吸附量与实验所测得的吸附量相吻合。(4)对吸附了Cu(Ⅱ)、Ni(Ⅱ)的TACKGM用1%的盐酸进行解析再生,实验表明TACKGM再生利用率高,解析3次后,吸附量可以达到第1次吸附吸附量的80%；用1%的NaOH,1%盐酸,3%氨水均难以解析吸附Cr(Ⅵ)的吸附剂,解析率均小于5%,解析效果很差。(5)结合红外图谱,吸附热力学和吸附动力学,推测TACKGM吸附Cu(Ⅱ)、Ni(Ⅱ)、Cr(Ⅵ)的吸附机理为：TACKGM对Cu(Ⅱ)、Ni(Ⅱ)的吸附较符合单分子层吸附,吸附中存在化学吸附、粒间扩散；TACKGM对Cr(Ⅵ)的吸附主要是电荷间的引力作用,同时存在粒间扩散；综合起来TACKGM吸附Cu(Ⅱ)、Ni(Ⅱ)、Cr(Ⅵ)的吸附是物理、化学吸附共同作用的结果。本课题通过改性制备的ACKGM是一种较好的重金属吸附材料,在固相萃取、富集Cu(Ⅱ)、Ni(Ⅱ)、Cr(Ⅵ)中有较好的应用前景。更多还原

【Abstract】 Natural polysaccharides are with a large number of active groups such as-OH and-NH2, rich in raw materials and easy to get. Its own or that can be prepared by modification are of certain adsorption capacity. KGM is one of natural polysaccharides similar with starch, cellulose, chitosan. Acording to its own characteristics, it has been widely used in food and chemical industry. It is a natural material with environmental effects.In this paper, ACKGM were prepared to be used in adsorption Cu(Ⅱ), Ni(Ⅱ), Cr(Ⅵ). The structure and surface morphology of each product were characterized using Infrared Spectrum, Scanning Electron Microscopy and X-diffraction.(1) The optimum conditions of the crosslinking, etherification, amination reaction were discussed. The settlement plot of CKGM was 53.5, that was prepared while the solvent concentration of isopropyl alcohol was 15%, the molar ratio of NaOH and konjac glucomannan was 1:2, the molar ratio of epichlorohydrin and konjac glucomannan was 1:1, the reaction temperature was 50℃, the reaction time was 6h; The CHKGM was prepared by CKGM and epichlorohydrin while the water rate of CKGM was 11～13%, the mol catalyst ratio of HClO4 and CKGM was 0.03:1, the reaction temperature was 80℃, the reaction time was 8h. The highest content of Cl and DSCl of CHKGM was 0.0503,0.2642 respectively. Cross-linked amino konjac glucomannan were prepared with Konjac glucomannan and amine agent which was ethylenediamine, diethylenetriamine, triethylenetetramine when the molar ratio dose of-NH2 of amine agent and CHKGM was 4:1, the reaction temperature was 60℃, the reaction time was 4h, the DSN of EACKGM、DACKGM、TACKGM was 0.0522,0.07695,0.1228 respectively.(2) EACKGM, DACKGM and TACKGM were applied to adsorption of Cu(Ⅱ), Ni (Ⅱ), Cr (Ⅵ), the order of the adsorption capacity was TACKGM> DACKGM> EACKGM. The affects on adsorption properties of TACKGM of the pH value of solution, dosage of TACKGM, the initial concentration of solution, adsorption time and adsorption temperature were discussed. The adsorption properties of Cu(Ⅱ), Ni(Ⅱ), Cr(Ⅵ) on TACKGM were 18.38mg·g-1、5.173 mg·g-1、21.51mg·g-1 respectively at 30℃.(3) The thermodynamics and dynamics of adsorption Cu(Ⅱ), Ni (Ⅱ), Cr (Ⅵ) on TACKGM were discussed, which provided their theoretical basis for the development and applications of TACKGM. The isothermal adsorption process of adsorption Cu(Ⅱ) and Ni(Ⅱ) could be described with the Langmuir model and the isothermal adsorption process of adsorption Cr (VI) could be described with Langmuir model or Freundlish model. By fitting the thermodynamic parameters of isotherm data, the adsorption process of adsorption Cu(Ⅱ), Ni(Ⅱ) was spontaneous, endothermic, entropy increasing while he adsorption process of adsorption Cr(Ⅵ) was spontaneous, exothermic and entropy decreasing; Compared with the pseudo-first order kinetic model, the pseudo second order kinetics model was more suitable for describing the process of adsorption Cu(Ⅱ), Ni(Ⅱ) Cr (Ⅵ) on TACKGM. The adsorption capacities obtained by fitting pseudo second order kinetics model were similar with the adsorption capacities obtained by experiments.(4) Desorption Cu(Ⅱ), Ni(Ⅱ)of TACKGM by 1% hydrochloric acid, adsorbent recycling rate was high, the adsorption capacities of regenerated TACKGM could reach the 80% of the original absorption capacities through desorpting for three times; Desorption Cr(VI) of TACKGM by 1% NaOH,1% hydrochloric acid and 3% ammonia solution respectively, it was difficult to resolve Cr (VI) from the adsorbent, desoption capacity was less than 5%.(5) Combination of the IR spectrum, the adsorption thermodynamics and kinetics, it suggested that the adsorption mechanismof Cu(Ⅱ), Ni(Ⅱ), Cr(Ⅵ) adsorption on TACKGM. The adsorption mechanisms of Cu(Ⅱ), Ni(Ⅱ) on TACKGMwere shown as: the adsorption was better in line with single-molecule layer adsorption, that concluded chemical adsorption and intergranular diffusion; The force between Cr(Ⅵ) and TACKGM were minly the electrostatic attraction, while there was intergranular diffusion; The adsorption mechanisms of Cu(Ⅱ), Ni(Ⅱ), Cr(Ⅵ) on TACKGM were the interaction results of physical adsorption and chemical adsorption.The adsorbent named ACKGM will be an friendly and environmentally material, which will be used in solid phase extraction and enrichment of Cu (Ⅱ), Ni (Ⅱ), Cr (Ⅵ).更多还原