Exclusion chromatographic separation of ionic from nonionic solutes

In an improved process for effecting separation of components in a solution comprising an ionic component and a nonionic component, the concentration of said ionic component ranging from about 1 weight percent to about 20 weight percent, and the concentration of said nonionic component ranging from about 1 weight percent to about 25 weight percent, said improved process comprising the steps of:

• (1) maintaining three zones operatively connected to one another in hydraulic order, said hydraulic order comprising flow of later mentioned side streams from an outlet of the third zone to the inlet of the second zone, from the outlet of the second zone to the inlet of the first zone and from the outlet of the first zone to the inlet of the third zone, each of said zones containing a bed of ion exchange resin, said resin being in its hydrogen form;
• (2) introducing a stream of said solution into said inlet of said first zone;
• (3) simultaneously withdrawing from an outlet of said first zone, a stream of ionic component-enriched, nonionic component-depleted solution as product and introducing a side stream of same into an inlet of said third zone;
• (4) simultaneously introducing aqueous media, which is both substantially ionic component-free and substantially nonionic component-free, into said inlet of said third zone and withdrawing from an outlet thereof a stream of relatively nonionic component-rich, substantially ionic component-depleted solution as product and introducing a side stream of same into an inlet of said second zone and withdrawing from an outlet of said second zone an ionic component-depleted and nonionic component-depleted solution and introducing a side stream of same into the inlet of said first zone;
• (5) effecting a stepped change in the flow connections for introduction and withdrawal of solutions among said zones wherein the flow of said solutions is redirected such that:
• (a) the solutions which were introduced into and withdrawn from the column, or columns which comprised said first zone are redirected to and from the column, or columns which comprised said third zone,
• (b) the solutions which were introduced into and withdrawn from the column, or columns which comprised said third zone are redirected to and from the column, or columns which comprised said second zone, and
• (c) maintaining the flow connections of said side streams, whereby, upon effecting said stepped change, the bed of resin which comprised said first zone becomes said second zone, the bed of resin which comprised said second zone becomes said third zone, and the bed of resin which comprised said third zone becomes said first zone and further whereby said stepped change simulates movement of said resin in a direction from said first zone through said second zone and then though said third zone;
• and
• (6) thereafter intermittently effecting subsequent stepped changes in the flow connections among said zones to further simulate said movement of said zones.