The Characteristic Calculation of a Phosphoric Acid Ion Exchanger using the Potentiometric Titration

전위차 적정법을 이용한 인산형 양이온교환수지의 특성 계산

  • Kim, T.I. (Department of Chemical Engineering, Chungnam National University) ;
  • Son, W.K. (Department of Polymer Science & Engineering, Chungnam National University)
  • 김태일 (충남대학교 화학공학공학과) ;
  • 손원근 (충남대학교 고분자공학과)
  • Received : 1999.05.19
  • Accepted : 1999.08.25
  • Published : 1999.10.10

Abstract

We calculated the characteristics of a phosphoric cation exchanger and studied on an accurately computable method to determine the ion exchange capacity for type of potentiometric titration curve. The ion exchanger was prepared by phosphorylation of a styrene-divinylbenzene copolymer with 4% crosslinking. The ion exchange capacity is 5.7 meq/g. The experimental pK values versus ${\mathit{x}}$ in phosphoric cation exchanger can be expressed as a linear equation. The ${\Delta}pK$ values were obtained from the slope of linear equation. The ${\Delta}pK$ values are the differences of antilogarithms(pK) values of the apparent equilibrium constant at complete and zeroth neutralization of the ion exchanger. Also the experimental pK values at ${\mathit{x}}=0.5$ were accorded well with theoretical data. And when it is titrated with NaOH and $Ba(OH)_2$ solutions, a good agreement between experimental and theoretical pK values for various ${\mathit{x}}$ was seen in all the potentiometric titration curves. We knew that the inflection point of potentiometric titration curve in the case of divalent ions are changed much large than that for monovalent ions. If the relation between g values and ${\partial}pH/{\partial}g$ was plotted to the Lorentz distribution curve, ion exchange capacity can be accurately evaluated.

Keywords

ion exchanger;phosphoric ion exchanger;potentiometric titration;equilibrium constant

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