Carboxylic acid group cation-exchange resins with

Weakly acidic cation-exchange resins have carboxylic groups (COOH) as the exchange sites. When operated on the hydrogen cycle, the weakly acidic resins are capable of removing only those cations equivalent to the amount of alkalinity present in the water, and most efficiently the hardness (calcium and magnesium) associated with alkalinity, according to these reactions ... 

Ion exchange, in which cation and/or anion resins are used to replace undesirable anionic species in liquid solutions with nonhazardous ions. For example, cation-exchange resins may contain nonhazardous, mobile, positive ions (e g., sodium, hydrogen) which are attached to immobile acid groups (e.g., sulfonic or carboxylic). Similarly, anion-exchange resins may include nonhazardous, mobile, negative ions (e.g., hydroxyl or chloride) attached to immobile basic ions (e.g., amine). These resins can be used to eliminate various species from wastewater, such as dissolved metals, sulfides, cyanides, amines, phenols, and halides. 

In the case of amorphous intermediate 4, the weakly acidic cation exchange resin DIAION WKIOO was selected as the CEC stationary phase. The resin comprises a methacrylate resin matrix and carboxylic acid, which functions as an exchange group with a high ion exchange rate. Figure 9.4 illustrates the concept behind the CEC procedure for 4 ... 

A bifunctional cation exchange resin carrying strongly acidic (sulfonic) and weakly acidic (carboxylic) groups was introduced in the mid-1960s but was to never merit a sustained commercial viability, and has since been discontinued. Undoubtedly, the acrylic and styrene copolymers with divinylbenzene form the basis of most commercially manufactured cation exchange resins available today. 

In addition to the commonly employed sulfonic acid cation exchanger, resins based on the carboxylic acid groups are sometimes employed under special conditions. These resins are effective for exchange reactions in neutral and alkaline solution. For example, the effluent from a saltsplitting reaction. Equation 5.23, can be treated with a carboxylic exchanger according to the reaction ... 

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