Preparation of a weakly basic ion exchanger by crosslinking starch with epichlorohydrin in the presence of NH4OH
Preparation of a weakly basic ion exchanger by crosslinking starch with epichlorohydrin in the presence of NH4OH
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DOI：
10.1016/s0144-8617(96)00060-4
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发表时间：
1996-05-01
影响因子：
11.2
通讯作者：
Thompson, AR
中科院分区：
文献类型：
--
作者：
Simkovic, I;Laszlo, JA;Thompson, AR
研究了在 NH4OH、NaOH 和水存在下淀粉与环氧氯丙烷的交联。优化反应并在水存在下通过固态 C-13-NMR、酸碱滴定和染料结合测量对产物进行分析。 NMR 证实了不同类型羟丙基的存在，但无法证实它们与多糖的连接，因为它们相对于所有其他 CH2 基团的丰度较小，而且侧链的运动远大于淀粉组分，尽管存在水，淀粉组分仍保持相当恒定。当反应中使用较多的 NH4OH 和较少量的水时，交联的、水不溶性产物的产率会增加。使用水不溶性淀粉的产品产率高于使用水溶性淀粉的产品产率。密闭容器（加压）反应条件提高了产物交换能力。对Cl-形式或非离子形式的产物进行电位滴定表明交换容量值比产物氮含量预期的要小，反映出产物完全质子化的困难。交联淀粉交换剂的染料结合是 pH 值依赖性的，在较低 pH 值下结合的染料数量增加，这与产品的弱胺性质一致。水解雷马素亮红 F3B（一种三价活性染料）在酸性条件下与淀粉基交换剂的结合效果（以摩尔计）比茜素红 S（一种单价媒染剂染料）低。染料结合能力略低于通过电位滴定测定的总离子交换能力，这表明部分交换位点对于染料是不可用的。
Crosslinking of starch with epichlorohydrin in the presence of NH4OH, NaOH and water was studied. The reaction was optimized and the products analysed by solid-state C-13-NMR in the presence of water, acid-base titration and dye-binding measurements. The presence of different types of hydroxypropyl groups was confirmed by NMR, but their linkage to polysaccharide could not be confirmed because of their minor abundance relative to all other CH2 groups, and because the motion of the sidechains is much greater than the starch component, which remains fairly constant despite the presence of water. Yield of crosslinked, water-insoluble product is increased as a greater amount of NH4OH and a lower amount of water is used in the reaction. Product yield using water-insoluble starch is higher than with a water-soluble starch. Closed-vessel (pressurized) reaction conditions increases product exchange capacity. Potentiometric titration of products in Cl--form or in non-ionized form indicated smaller exchange capacity values than expected from product nitrogen contents, reflecting the difficulty in fully protonating the products. Dye binding by the crosslinked-starch exchangers is pH-dependent, with an increased quantity of dye bound at lower pH, which is consistent with the weak-amine nature of the products. Hydrolyzed Remazol Brilliant Red F3B, a trivalent reactive dye, binds less effectively under acidic conditions, on a molar basis, to the starch-based exchangers than does Alizarin Red S, a monovalent mordant dye. Dye-binding capacities are somewhat lower than the total ion-exchange capacities determined by potentiometric titration, suggesting that a portion of the exchange sites are unavailable to the dyes.