Stellenbosch, South Africa 13.1 PRINCIPLES OF ION EXCHANGE 13.1-1 Ion-Exchange Resins
Stellenbosch, South Africa 13.1 PRINCIPLES OF ION EXCHANGE 13.1-1 Ion-Exchange Resins
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南非斯泰伦博斯 13.1 离子交换原理 13.1-1 离子交换树脂
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
D. Cloete
中科院分区：
文献类型：
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作者：
M. Streat;F. Louis;D. Cloete
聚苯乙烯磺酸阳离子树脂 苯乙烯（乙烯基苯）使用有机过氧化物催化剂很容易聚合，形成线性聚苯乙烯。如果二乙烯基苯 (DVB)（通常占总量的 8% 左右）与苯乙烯混合，就会形成三维聚合物网络。 DVB 交联形成三维结构，使聚合物不溶。因此，特征性的球形离子交换珠是通过悬浮聚合制备的。将催化的单体混合物在设计为得到所需液滴尺寸的条件下搅拌到水中，加热几个小时后，将产生固体球形珠。在此阶段，珠子是疏水性的，但可以吸收一些有机液体，例如甲苯，从而导致膨胀。溶胀程度实际上用作聚合物交联的量度。首先用惰性溶剂（例如二氯乙烷）溶胀聚合物，将珠子转化为离子交换树脂。然后在约 80°C 下用浓硫酸处理它们以制备阳离子交换剂。阳离子交换剂完全不溶，但可自由渗透水，并且在表面干燥状态下含有约50重量%的H2O。最终材料是磺化交联聚苯乙烯，它是商业用途中使用最广泛的阳离子交换树脂。树脂吸附任何离子的总容量约为每克0.00525当量，通常表示为5.25meq/g，根据烘干的树脂计算。
POLYSTYRENE SULFONIC ACID CATION RESINS Styrene (vinylbenzene) is polymerized readily, using an organic peroxide catalyst, to form linear polystyrene. If divinylbenzene (DVB) (usually about 8% of the total) is mixed with the styrene, a three-dimensional polymer network is formed. The DVB cross-links give a three-dimensional structure that renders the polymer insoluble. The characteristic spherical ion-exchange beads therefore are made by suspension polymerization. The catalyzed monomer mixture is stirred into water under conditions designed to give the desired droplet size which, after several hours heating, will yield solid spherical beads. At this stage, the beads are hydrophobic but can absorb some organic liquids such as toluene, swelling as a result. The extent of swelling is used in fact as a measure of the crosslinking of the polymer. The beads are converted into an ion-exchange resin, by first swelling the polymer with an inert solvent such as ethylene dichloride. They are then treated with concentrated sulfuric acid, at about 80C, to make a cation exchanger. The cation exchanger is totally insoluble but is freely permeable by water and contains about 50% H2O by weight in an apparently dry state. The final material is sulfonated crosslinked polystyrene which is the most widely used cation-exchange resin in commercial use. The total capacity of the resin for sorbing any ion is about 0.00525 equivalent per gram, normally expressed as 5.25 meq/g, calculated on oven-dried resin.