METHOD OF EVALUATION OF TRANSFER NUMBERS IN ION-EXCHANGE MATERIALS

Abstract

A new method of differential itn-metry has been developed for accurate determination of ion transfer numbers in materials with ion-exchange properties. Such materials include ion exchange membranes, liquid phase ion exchangers and ionic liquids, industrial ion exchange resins. The method is intended as an alternative simplified assessment of the functional properties of ion-exchange resins used in industrial technologies of water purification, water treatment, and extraction at enterprises of various industries. Such accurate information is obtained in special laboratories at enterprises by long-term and expensive physical and chemical methods. Transfer numbers give an indirect assessment of the quality of ion exchangers, but the method of differential itn-metry gives a result in a short 30-minute experiment on the electrolysis of a NaOH or NaCl solution in a three-chamber electrolyzer reactor. The electrolyzer-reactor contains an electrolyte volume of up to 40 cm3. The middle chamber of the electrolyzer-reactor has a variable width from 0.05 to 0.2 cm and an area of 10 cm2 perpendicular to the direction of the electric current. The primary result of each experiment was the functions of the electrolyte concentration dynamics C(τ) in the extreme cathode and anode chambers of the electrolyzer- reactor, where the dynamics of the readings of the flow resistometric sensor developed by us were recorded during the electrolysis process. The effective transfer number itn* was determined by mathematical data processing using a system of approximation functions. The method of differential itn-metry will be effective for other resins with amphoteric properties. The use of such a method could be used in works for the study of a wide range of problems in environmental monitoring and management of environmental projects.