US 4,147,623 AGranted

Hydroxylamine purification via ion exclusion

AssigneeAllied Chemical Corporation

InventorsFred W. Koff, Allen A. Tunick, Stylianos Sifniades

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Abstract

A process for separating hydroxylamine from an aqueous solution thereof also containing salts of cations whose corresponding free bases have base dissociation constants greater than 10.sup.-7. Said solution is brought to a pH of 6-11 and is passed through a bed of strongly ionic exchange resin loaded with compensating ions whereby hydroxylamine is retained in the gel volume of the resin bed and the ions in solution are substantially excluded from the resin. The ionic salts accordingly move faster through the bed and predominate in a first effluent fraction and the hydroxylamine appears predominantly in a later effluent fraction. Hydroxylammonium salts can be crystallized from the effluent hydroxylamine solution after addition of a stoichiometric amount of an appropriate acid.

Claims20

Dependent claims

A process for separating hydroxylamine from aqueous solutions containing hydroxylammonium salts in mixture with salts of cations whose corresponding bases have base dissociation constants of at least 10.sup.-7 comprising:

(a) bringing such solution to a pH of between about 6 and 11;
(b) sequentially passing the resulting solution and water through a cation exchange resin bed loaded with charge compensating cations which will compose a base having, in aqueous solution a base dissociation constant substantially greater than that for hydroxylamine (K.sub.b = 10.sup.-8) or through an anion exchange resin bed loaded with charge compensating anions, which will compose an acid having in aqueous solution an acid dissociation constant substantially greater than that for hydroxylammonium ion (K.sub.a = 10.sup.-6);
(c) removing from the bed a first effluent containing predominantly cations eluted from such cation exchange resin bed or anions eluted from such anion exchange bed and a later effluent containing predominantly hydroxylamine thereby separating the hydroxylamine from the aforesaid salts.

Dependencies are inferred from the claim text.