Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States.
Langmuir. 2013 Apr 23;29(16):5037-49. doi: 10.1021/la3050016. Epub 2013 Apr 8.
We have successfully developed a simple one-step method of preparing high-performance supramolecular polysaccharide composites from cellulose (CEL), chitosan (CS), and (2,3,6-tri-O-acetyl)-α-, β-, and γ-cyclodextrin (α-, β-, and γ-TCD). In this method, [BMIm(+)Cl(-)], an ionic liquid (IL), was used as a solvent to dissolve and prepare the composites. Because a majority (>88%) of the IL used was recovered for reuse, the method is recyclable. XRD, FT-IR, NIR, and SEM were used to monitor the dissolution process and to confirm that the polysaccharides were regenerated without any chemical modifications. It was found that unique properties of each component including superior mechanical properties (from CEL), excellent adsorption for pollutants and toxins (from CS), and size/structure selectivity through inclusion complex formation (from TCDs) remain intact in the composites. Specifically, the results from kinetics and adsorption isotherms show that whereas CS-based composites can effectively adsorb the endocrine disruptors (polychlrophenols, bisphenol A), their adsorption is independent of the size and structure of the analytes. Conversely, the adsorption by γ-TCD-based composites exhibits a strong dependence on the size and structure of the analytes. For example, whereas all three TCD-based composites (i.e., α-, β-, and γ-TCD) can effectively adsorb 2-, 3-, and 4-chlorophenol, only the γ-TCD-based composite can adsorb analytes with bulky groups including 3,4-dichloro- and 2,4,5-trichlorophenol. Furthermore, the equilibrium sorption capacities for the analytes with bulky groups by the γ-TCD-based composite are much higher than those by CS-based composites. Together, these results indicate that the γ-TCD-based composite with its relatively larger cavity size can readily form inclusion complexes with analytes with bulky groups, and through inclusion complex formation, it can strongly adsorb many more analytes and has a size/structure selectivity compared to that of CS-based composites that can adsorb the analyte only by surface adsorption.
我们成功开发了一种从纤维素（CEL）、壳聚糖（CS）和（2,3,6-三-O-乙酰基）-α-、β-和γ-环糊精（α-、β-和γ-TCD）制备高性能超分子多糖复合材料的简单一步法。在该方法中，[BMIm(+)Cl(-)]离子液体（IL）用作溶解和制备复合材料的溶剂。由于回收了大部分（>88%）用于再利用的 IL，因此该方法是可回收的。XRD、FT-IR、NIR 和 SEM 用于监测溶解过程并确认多糖在没有任何化学修饰的情况下再生。结果表明，每个组分的独特性质包括优异的机械性能（来自 CEL）、对污染物和毒素的出色吸附（来自 CS）以及通过包合形成的尺寸/结构选择性（来自 TCDs）在复合材料中得以保留。具体而言，动力学和吸附等温线的结果表明，尽管基于 CS 的复合材料可以有效吸附内分泌干扰物（多氯酚、双酚 A），但其吸附与分析物的大小和结构无关。相反，基于γ-TCD 的复合材料的吸附强烈依赖于分析物的大小和结构。例如，尽管所有三种基于 TCD 的复合材料（即α-、β-和γ-TCD）都可以有效吸附 2-、3-和 4-氯酚，但只有基于γ-TCD 的复合材料可以吸附具有大基团的分析物，包括 3,4-二氯和 2,4,5-三氯酚。此外，基于γ-TCD 的复合材料对具有大基团的分析物的平衡吸附容量远高于基于 CS 的复合材料。总之，这些结果表明，具有相对较大空腔尺寸的γ-TCD 基复合材料可以与具有大基团的分析物容易地形成包合物，并且通过包合形成，它可以强烈吸附更多的分析物，并且与仅通过表面吸附吸附分析物的 CS 基复合材料相比具有尺寸/结构选择性。
