CAS OpenIR
离子液体/低共熔溶剂中甲壳素制备及功能化研究
冯咪
Subtype博士
Thesis Advisor张锁江
2019-07-01
Degree Grantor中国科学院大学
Degree Discipline应用化学
Keyword从废弃虾蟹壳提取的甲壳素,可用于医药、农业及纺织等领域,实现废弃资源回收,有利于可持续发展。然而,传统甲壳素及其功能化产品的制备工艺,需要大量酸碱溶液及有机溶剂,流程长,水耗大,污染大,已逐渐被淘汰。离子液体具有极低的蒸汽压、良好的热稳定性、可设计的结构及丰富的氢键网络等特点,为甲壳素制备及功能化提供了新选择。目前离子液体中甲壳素的制备及功能化研究尚少,且存在成本高、水耗大及离子液体难循环等问题。此外,尚无有关直接从虾蟹壳制备甲壳素功能化产物的报道。基于以上研究背景,本论文以虾壳为原料,开展基于离子液体/低共熔溶剂中的甲壳素、以及甲壳素/zn复合物、o-酰化甲壳素等功能化甲壳素制备的基础研究,为废弃虾壳的直接转化提供了新思路,主要研究内容及创新性研究成果如下:(1)无机盐水溶液-咪唑离子液体体系中甲壳素的制备。在此体系中,无机盐水溶液通过离子交换去除碳酸钙,离子液体1-丁基-3-甲基咪唑氯盐([Bmim]Cl)通过氢键作用去除蛋白质及引入的杂质镍,从而制得甲壳素。考察了无机盐种类、实验温度对除钙的影响,以及实验温度、料液比对除蛋白及杂质镍的影响。结果表明,虾壳粉依次与niso4水溶液(20 Wt%)、[Bmim]Cl在130 °c反应24 H,可得到纯度为98.8 Wt%的甲壳素。由此可见,离子交换可以去除虾壳中碳酸钙,同时负载金属盐,为甲壳素/金属复合物制备提供新思路。(2)磷酸酯类离子液体-无机盐水溶液体系中甲壳素/zn复合物的制备。首先利用磷酸酯类离子液体去除虾壳中蛋白质,随后利用zn(Oac)2·2h2o水溶液去除碳酸钙同时负载锌,得到甲壳素/zn复合物。考察了磷酸酯类离子液体种类、实验温度、料液比、实验时间对除蛋白的影响,以及zn(Oac)2·2h2o水溶液浓度、实验时间、温度对除钙及负载锌的影响,初步评价了离子液体循环使用性能、甲壳素/zn复合物对pet醇解的催化性能。实验结果表明,在130 °c条件下,虾壳粉依次与1-乙基-3-甲基咪唑磷酸甲酯([Emim][Dmp])、zn(Oac)2·2h2o水溶液(20 Wt%)反应24 H,得到纯度为99.1 Wt%,锌含量为13.4 Wt%的甲壳素/zn复合物 所用[Emim][Dmp]循环使用五次时,仍保持原有除蛋白质能力 所得甲壳素/zn复合物,甲壳素构型为α,锌离子为znCo3/zn(Oh)2,其对pet醇解表现出良好的催化性能。由此可见,不同离子液对虾壳中蛋白质、甲壳素优先溶解能力不同。(3)金属低共熔溶剂水溶液中甲壳素/zn复合物的制备。基于以上研究思路,设计合成金属低共熔溶剂尿素/zn(Oac)2·2h2o(u-zn),其水溶液同时具备除钙、除蛋白及负载金属功能,实现了从虾壳一步制备甲壳素/zn复合物的目的。考察了u-zn水溶液浓度、料液比、实验时间及温度对产物纯度及锌负载量的影响,测试了甲壳素/zn复合物的抗菌效果,探究了u-zn水溶液与虾壳中各组分相互作用,揭示了碳酸钙去除、锌负载及蛋白质去除的机理。实验结果表明,虾壳粉与u-zn(30 Wt%)在130 °c反应24 H,可得纯度为97.2 Wt%、锌含量为34.7 Wt%的甲壳素/zn复合物,其对革兰氏阴性菌及阳性菌具有良好的抑制作用。甲壳素/zn复合物中甲壳素构型保持为α,其聚合度高于甲壳素标样,锌离子以碱式碳酸锌(zn5(Co3)2(Oh)6)的形式存在。机理研究证实,配位能力较高的锌离子与虾壳中钙离子交换,原位形成碳酸锌,然后水解为碱式碳酸锌,释放co2 虾壳中蛋白质分子被包裹于水溶液中的u-zn簇内,溶解于其中,从而去除。由此可见,u-zn水溶液的离子交换能力及聚集作用,是甲壳素/zn复合物形成的主要原因。(4)酸性低共熔溶剂中酰化甲壳素的制备。延续多功能低共熔溶剂设计的理念,设计合成11种氯化胆碱-有机酸低共熔溶剂,同时具备除钙、除蛋白、及酰化的能力,实现从虾壳一步制备酰化甲壳素的目的。考察了低共熔溶剂种类、实验温度、实验时间、料液比及水含量对酰化甲壳素纯度及酰化度的影响,评价了酸性低共熔溶剂的循环性能,测试了酰化甲壳素的抗菌及抗肿瘤效果,探究了低共熔溶剂与虾壳各组分的相互作用,明确了虾壳中碳酸钙去除、蛋白质去除及甲壳素酰化的机理。实验结果表明,虾壳粉与氯化胆碱/dl-苹果酸(1:2,chcl 1/dl-mal 2)在150 °c条件下反应3 H,得到了纯度为98.6 wt%,酰化度为0.46的o-苹果酸酰化甲壳素,其对革兰氏阳性菌及神经胶质瘤c6细胞系表现出一定抑制效果。结构分析确定,所得产物确实为o-酰化甲壳素,且其相对分子质量折合计算后高于甲壳素标样。机理研究证实,在此体系中,虾壳中碳酸钙与酸性低共熔溶剂游离出的h+反应,形成水溶性有机酸盐,同时释放co2,形成绵密气泡 虾壳中一部分蛋白质在酸性条件下降解为可溶于水的氨基酸,另一部分蛋白质与低共熔溶剂形成氢键作用,溶解于其中,转变为水溶性蛋白 甲壳素结构被低共熔溶剂撑开,反应活性提高,在h+催化下与低共熔溶剂反应,从而生成酰化甲壳素。由此可见,所用低共熔溶剂的酸度、氢键形成能力是o-酰化甲壳素生成的主要原因。
Abstract

The extracted chitin from waste shrimp shells can be applied in various fields including medicine, agriculture, and textile industry, which is valuable and sustainable. However, the chitin and chitin-based products are usually prepared with acid, base and special organic solvents, which no long meets the environment requirement now. Ionic liquids (ILs), a new generation green solvent, has low vapor pressure, high thermostability, designable structure, and numerous hydrogen bonding net. They provide new options for chitin extraction and utilization. Currently, the literatures about chitin extraction and utilization using ionic liquid are still few. Unfortunately, the reported IL-based methods still have the problems such as high cost, high water consumption, and difficulty in recycle. Moreover, there is still no literature about direct preparation of chitin-based products from shrimp shells. Herein, this work used the shrimp shells as raw material to prepare chitin, chitin/Zn compsotie, and O-acylated chitin, providing alternation for waste shrimp shells utilization. The main innovative work and results are as follows.(1) Study on the preparation of chitin using combined inorganic salt aqueous solution-ionic liquid. In this part, NiSO4 aqueous solution (aq.) was employed to remove calcium carbonate by ion exchange, and the 1-butyl-3-methyl-imidazolium chlorine ([Bmim]Cl) was used to remove protein and the introduced nickel in the first step through hydrogen interaction. Through the two steps, the high purity chitin was prepared. The results showed that the type of the inorganic aq., and temperature, liquid/solid ratio affected the purity of the chitin. Finally, the chitin with purity 98.8 wt% was obtained by sequential treatment with NiSO4 aq. (20 wt%) and [Bmim]Cl at 130 °C for 24 h. It can be seen that ion exchange can remove calcium carbonate from shrimp shells and simultaneously load metal salts, which provides a new option for the preparation of chitin/metal composites.(2) Study on the preparation of chitin/Zn composite from shrimp shells using phosphate ionic liquid and inorganic salt aqueous solution. The employed ILs hold the ability of deproteinization, and the inorganic salt aq. has the ability of decalcification and zinc loading. Systematically, the effects of the IL type, experiment temperature, liquid/solid ratio, and time on the protein removal were explored firstly, then the concentration of Zn(OAc)2·H2O aq., experiment time and temperature were explored for decalcification and zinc-loading. Under the optimal conditions, the chitin/Zn composite with purity 99.1 wt% and 13.4 wt% zinc was obtained, displaying a good catalytic effect on the PET glycolysis. The characterization of the chitin/Zn composite showed that the chitin kept α-form, and the zinc existed as ZnCO3/Zn(OH)2 with forming interaction with chitin. It can be seen that the preferential solubility of protein and chitin in different ionic solutions is different.(3) Study on the chitin/Zn composite preparation with metal deep eutectic solvent. Based on the second part research, the multifunctional DES, namely urea/Zn(OAc)2·2H2O (1:2, U-Zn), was designed and synthesized. The U-Zn aq. can remove calcium carbonate, protein, and load zinc, simultaneously. The factors including the concentration of U-Zn aq., liquid/solid ratio, experiment time and temperature were studied to determine their effect on the purity and Zn-loading of chitin. Under the optimal conditions, the chitin/Zn composite with purity 97.2 wt% and 34.7 wt% zinc was obtained, exhibiting high anti-bacterial effect on the Gram negative and positive bacterium. Moreover, the chitin/Zn composite was characterized, suggesting that the chitin kept α-form, and zinc was the Zn5(OH)2(CO3)6 with forming interaction with chitin. Importantly, experiments and spectroscopy results revealed the mechanism of chitin/Zn composite formation. The zinc ion with higher coordination ability can exchange with calcium ion in-suit forming zinc carbonate, which hydrolyzed to Zn5(OH)2(CO3)6 and CO2. Additionally, the protein was surrounded with U-Zn clusters resulting in dissolution and removal. It can be seen that the ion exchange capacity and aggregation of the U-Zn aqueous solution are the main reasons for the formation of the chitin/Zn composite.(4) Study on the O-acylated chitin with acid deep eutectic solvents. 11 multifunctional DES composed of choline chloride and organic salt were designed and synthesized. These DESs have the ability of decalcification, deproteinization, and acylation. The influences of the chitin purity and degree of substitution (DS) were explored, which included DES type, experiment temperature, time, liquid/solid ratio, and water contents of DES. With the optimal NADES (choline chloride/DL-malic acid 1:2, ChCl 1–DL Mal 2) treatment under the optimal conditions, the highest purity O-malate chitin was obtained with purity 98.6 wt% and DS 0.46. The O-malate chitin showed an inhibitory on the Gram-positive bacterium and C6 glioma cells. Characterizations further proved that product was the O-malate chitin. Furthermore, process of O-acylated chitin was discussed. During the process, the H+ released from DES was reacted with the calcium carbonate, producing CO2 and soluble organic calcium salts. Meanwhile, the H+ was reacted with part of protein forming the amino acid. The rest part of protein was dissolving in the DES by hydrogen interaction. Additionally, the DES activated the chitin by swelling its stable structure firstly, then reacted with chitin under the acid conditions to produce the O-acylated chitin. Thus, the acidity and hydrogen bond forming ability of the used deep eutectic solvent are the main reasons for the formation of O-acylated chitin.

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/40653
Collection中国科学院过程工程研究所
Recommended Citation
GB/T 7714
冯咪. 离子液体/低共熔溶剂中甲壳素制备及功能化研究[D]. 中国科学院大学,2019.
Files in This Item:
File Name/Size DocType Version Access License
离子液体-低共熔溶剂中甲壳素制备及功能化(15594KB)学位论文 限制开放CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[冯咪]'s Articles
Baidu academic
Similar articles in Baidu academic
[冯咪]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[冯咪]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.