Sorption of Organic Compounds Onto Carboxylic Cation-Exchangers

Sorption onto carboxylic cation exchangers is an effective and widely used method for purification, isolation and concentration of biologically active compounds. The process and efficiency of sorption depends on structure and physicochemical properties of sorbent and bio-compound, as well as pH, composition and temperature of sorption solution.The most important characteristic of the ion-exchanger is the ionization of its functional groups. The ionization process depends on pH, neutral salt concentration and temperature. Binding of organic compounds occurs mostly via electrostatic interactions. Therefore the condition of functional groups has a significant influence on sorption ability. Three weak acidic cation exchangers with different structures were investigated - two of them (K-120, K-10) were synthesized by water-dispersion polymerization, but the third is a commercially available sorbent Amberlite IRC-50. The method of potentiometric titration was used to describe the ionization of functional groups. Ionization parameters were found from titration results using the Henderson-Hasselbach equation. Sorption properties and kinetics were studied in batch experiments with different organic compounds. To choose the optimal conditions for the sorption process, correlation between sorption efficiency, pH value and neutral salt concentration has been studied for each compound