Abstract
UDC 541.183.12:541.135
DOI https://doi.org/10.5281/zenodo.1464855
The experimental technique and equipment to study the kinetics of the ion exchange processes in weak electric fields on the ion-exchange resins by computer resisto-metrics method have been described. The interaction scheme of electrical and diffusion ion fields in the solid phase of the ion exchanger has been discussed. It is shown that during the superposition of a weak electric field to the ion exchanger globule, the vectors of the total speed of displacement of ions generate the ellipsoidal surface, displaced to the side of the vector of the electric field strength relative to the center of the particle. The asymmetry of the velocity field illustrates a change in the balance of ionic flows and their acceleration in the direction of the electric field vector. The test unit to study the ion exchange dynamics, which includes a convective reactor, a built-in column with the portion of the exchanger, a temperature control system, a flowing sensor of the electrical resistance of the solution, an electronic resistometer, a potentiostat – galvanostat, has been described. Three experimental methods have been described: 1 – with the circulating suspension of exchanger in the closed volume of thr convective reactor, which makes it possible to limit the influence of diffusion resistance in the solution; 2 – with the filtration of the solution through the exchanger in the built-in column in the closed volume of the convective reactor; and 3 – the open filtration of the solution through the column. In all methods the exchange process proceeds in a nonstationary mode. The methods differ by the form of the information obtained about the dynamics of the process, which is illustrated by examples. It is shown that the speed of the ion flux in the solid phase is constant and does not depend on the saturation value of the exchanger in the suspension regime of exchange in the base interval time of the process. The effect is caused by the action of the principle of electroneutrality on two ion fluxes with the charges of the same sign but with opposite concentration gradients. Computer resistometrics can be effective as a nonchemical method of an accelerated test of exchange properties of ion-exchange materials.
Keywords: exchanger, ion exchange, exchange capacity, electric field, diffusion, conductivity, sensor, resistometer.