An automatic titrator for measurement of exchange capacity and titration curve of ion-exchanger.

Abstract

An automatic titrator which allows the titration under the condition of a slow exchange rate was trially manufactured and tested using zirconium phoshate. This instrument consists of an ion meter, auto-piston burette, digital multimeter and a personal computer. The results of each titration volume, pH and titration curve were recorded using the automatic titrator. The measurement time, of each titration volume and end point condition were variable in order to accommodate the user's request. In this study, standard measurement times (smt) for each titration volume were 1, 2 and 4 h. When the smt did not satisfy the condition for an end point in each series of titration experiment, these smt were extended within the maximum measurement termination times (mmtt). These mmtt were set at 4 h for smt of 1, 2 and 6 h for smt of 4 h, respectively. The titration curve for zirconium phosphate using sodium hydroxyde indicates two steps. At smt of 1 h, the system did not reach equilibrium, which can be detected by two peaks appearing at the second equivalence point. It is possible to identify the second equivalence point by careful analysis of the titration record. The results are satisfactory for the smt of 1, 2 and 4 h, though the curve of smt at 1 h shows little difference from others, except for a more complicated structure at the second equivalence point. © 1991, The Japan Society for Analytical Chemistry. All rights reserved.