Weakly acidic cation exchange resins are weakly acidic IERs that have carboxylic acid groups as ion-exchangable groups, as Figs 1 and 2. DIAION™ WK10, made from methacrylic acid, and DIAION™ WK40, made from acrylic acid, are in this grouping.
<Fig.1> Chemical structure of Acrylic acid type weakly acidic cation exchange resins.
<Fig.2> Chemical structure of Methacrylic acid-type weakly acidic cation exchange resins.
WK10 grades (methacrylic-type) are weak acid cation exchange resins having carboxylic acid functionalities. They have a pK value of approximately 6. WK10 has a high reaction rate, and WK11 has a high total exchange capacity. These grades are mainly used for special applications such as purification of pharmaceuticals, foods and organic chemicals. WT01S has a high reaction rate and high adsorption capacity. It is mainly used for the purification of pharmaceuticals and foods. WT01S is offered in 100-300 μm particle distribution.
WK40L is a weak acid cation exchange resin with carboxylic acid functionality based on porous acrylic polymer matrix. It has a pK value of approximately 5.3. The acrylic type WK40L resin has a higher total capacity than methacrylic type resins. It is mainly used for water treatment applications for removal of hardness ions in the presence of bicarbonate alkalinity.