An ion-exchange process with thermal regeneration. V. Multistage operation

Abstract

Multistage column experiments have been performed using a mixed bed of finely divided weakly acidic and weakly basic ion-exchange resins with thermal regeneration of the resins at 80º. A product water fraction with a concentration of 200- 250 p.p.m. can be obtained using such a column from a feed water containing 1000 p.p.m. of sodium chloride. When the same feed water is used as the regenerant at 803 an effluent having a peak concentration of about 5000 p.p.m. can be obtained. A solution of 1000 p.p.m. magnesium sulphate can be similarly demineralized. The performance of the resin column is highly dependent on the pH value to which it has been buffered by prior treatment with acid or alkali. It is also shown that thermal regeneration is feasible when the resins are used in a softening cycle.