Changes in thermodynamic functions in the two-temperature process of concentration and purification of electrolyte solutions on KB-4P2 polymethacrylic ionite

摘要

Temperature dependences of the differential Gibbs energies and sorption enthalpies of water on KB-4P2 polymethacrylic ionite in Ca ~(2+), Mg ~(2+), Ni ~(2+), and Na ~+ forms are determined. It is shown that during the two-temperature concentration and purification of electrolyte solutions, the content of the so-called "free" water in the ionite, the absorption of which by the latter is characterized by very low differential values of the Gibbs energy and enthalpy, changes with a change in the temperature of the polymethacrylic cationite suspension and electrolyte solution. It is established that the rather energy-consuming step of heating the phase of ionite and solution contributes mainly to the enthalpy of this process. Equations for the temperature dependences of the activity of water for solutions of sodium, magnesium, calcium, and nickel chlorides of various concentrations are given.