GB1075049A - Recovery of iodine - Google Patents

Abstract

Iodine is recovered from an aqueous solution of an iodide salt by alternately contacting an anion-exchange resin with chlorinated and non-chlorinated portions of the aqueous solution, whereby the resin picks up iodine, eluting iodine from the exchange resin and recovering free iodine from the eluate. The chlorinated solution preferably contains 1-5 moles of chlorine per equivalent of iodine. Sodium hydroxide or sodium chloride may be used for eluting the iodine from the resin and the free iodine may be recovered in the case of elution with NaOH by the addition of a mineral acid and sodium iodate to the eluate. Alternatively, the elution may be effected using sodium hydroxide and then sodium chloride as eluants, which process is described in Specification 1,058,429 from which the present application is divided. The ion-exchange resin may be a strongly basic quaternary ammonium resin or a weakly basic resin, e.g. of the polyamine type, both being in either the salt or hydroxide form. In a preferred method of working the chlorinated and non-chlorinated solutions are passed alternately through 2 anion-exchange resin columns in series until the first column is exhausted, then the solutions are passed through the second and a third column of freshly regenerated resin while iodine is eluted from the first column.