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Интеллектуальная Система Тематического Исследования НАукометрических данных |
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Influence of temperature on enthalpy of ion exchange of differently charged ions on carboxylic cation exchangersтезисы доклада
- Авторы: Ilyukhina E.A., Ivanov V.A., Gavlina O.T., Gorshkov V.I.
- Сборник: Abstract book of the XVI International Conference on "Chemical Thermodynamics in Russian", 1-6 July 2007, Suzdal, v. II, p. 408
- Том: 2
- Тезисы
- Год издания: 2007
- Первая страница: 408
- Последняя страница: 408
- Аннотация: Ion exchange processes are used in various fields. Wide application of ion exchange is restricted by the need of ion exchangers regeneration with the use of a big quantity of chemical reagents. That’s why the decrease of consumption of auxiliary reagents and creation of reagentless methods for ion-exchange separation and purification of substances is one of most important direction in ion exchange development. The use of dependence of selectivity on temperature is one of the possible ways for solving this problem. Earlier the authors have found the significant influence of temperature on ion exchange of differently charged ions on carboxyl cation exchangers. This effect was used in new processes of separation and purification of substances. In this work the differential enthalpy for exchange of calcium or nickel to sodium ions from solutions with concentrations within the range of 2.5 to 2.8 equiv/l on the polyacrylic (KB-2e4) and polymethacrylic (KB-4P2 and KB-4) cation exchangers of gel type, macroporous polyacrylic cation exchangers (Purolite C104-Fl and Levatite CNP-80) has been studied in temperature interval of 273K to 400K. The differential enthalpy refers to ion exchanger of fixed composition (the fixed quantities of exchangeable ions, water and co-ions) and characterizes the change of one equivalent of one of ions from solution to one equivalent of other ion from the infinitely large quantity of ion exchanger of fixed composition, while the exchange ions in solution are in the standard states. The new method for determination of differential enthalpy of ion exchange on the selective ion exchangers based on analysis of solution composition only in the equilibrium system for two different temperatures has been suggested. In this case the error of determination of differential enthalpy is less as one in usual methods. The studying of influence of temperature on ion exchange equilibrium on carboxylic resins with different fractions of divalent ions showed that the rise of the temperature increases significantly the selectivity with respect to divalent ions. It has been determined, that the rise of selectivity of carboxylic type cation exchangers with temperature is accompanied also by significant growth of differential enthalpy of ion exchange of differently charged ions according to linear dependence. For example, in the process of Ca – Na exchange on KB-4P2 and KB-4 resins in temperature interval of 273K to 400K the differential enthalpy grows from 7-8 kJ/equiv to 22-26 kJ/equiv. The influence of ionic composition of resin on differential enthalpy is less essential. Thus, the rise of enthalpy with temperature leads to the significant growth of selectivity of carboxylic type resins to divalent ions. The use of carboxylic cation exchangers for purification of concentrated solutions of alkali-metal salts from divalent ions at high temperatures seems to be very promising, because under these conditions their selectivity is much higher while the regeneration of ion exchanger goes easier at low temperatures. This work was supported by the Russian Foundation for Basic Research (№ 04-03-33020).
- Добавил в систему: Иванов Владимир Александрович