Sorption of carboxylic acid from carboxylic salt solutions at PHS close to or above the pK.sub.a of the acid, with regeneration with an aqueous solution of ammonia or low-molecular-weight alkylamine
AssigneeThe Regents of the University of California
InventorsC. Judson King, Lisa A. Tung
Life of this patent
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Abstract
Carboxylic acids are sorbed from aqueous feedstocks at pHs close to or above the acids' pH.sub.a into a strongly basic organic liquid phase or onto a basic solid adsorbent or moderately basic ion exchange resin. the acids are freed from the sorbent phase by treating it with aqueous alkylamine or ammonia thus forming an alkylammonium or ammonium carobxylate which dewatered and decomposed to the desired carboxylic acid and the alkylamine or ammonia.
Claims25
A process for recovering carboxylic acid from a carboxylic acid-containing aqueous feedstream having a pH close to or above the pK.sub.a of the acid comprising:
- (a) contacting the carboxylic acid-containing feedstream at a pH close to or above the pK.sub.a of the acid with an acid-sorbing phase selected from a strongly basic sorbent, a strongly basic extractant and a weak to moderate-basicity anion exchanger under conditions whereby carboxylic acid is sorbed from the feedstream to the acid-sorbing phase, thereby forming an acid-depleted aqueous feedstream and an acid-enriched acid-sorbing phase;
- (b) separating the acid-depleted aqueous feedstream from the acid-enriched acid sorbing phase;
- (c) contacting the separated acid-sorbing phase with an aqueous solution of low molecular weight alkylamine or ammonia, thereby solubilizing said carboxylic acid from the sorbing phase into said aqueous solution as alkylammonium or ammonium carboxylate, and forming a carboxylic-acid lean acid-sorbing phase;
- (d) separating the aqueous solution of alkylammonium or ammonium carboxylate from the acid-lean acid-sorbing phase;
- (e) treating the aqueous solution of alkylammonium or ammonium carboxylate to decompose the alkylammonium or ammonium carboxylate to yield the carboxylic acid and the alkylamine or ammonia;
- and
- (f) recovering the carboxylic acid yielded in step (e).
A process for recovering carboxylic acid from a carboxylic acid-containing aqueous feedstream having a pH close to or above the pK.sub.a of the acid comprising:
- (a) contacting the carboxylic acid-containing feedstream at a pH close to or above the pK.sub.a of the acid with an acid-sorbing phase selected from a strongly basic sorbent, a strongly basic extractant and a weak to moderate-basicity anion exchanger under conditions whereby carboxylic acid is sorbed from the feedstream to the acid-sorbing phase, thereby forming an acid-depleted aqueous feedstream and an acid-enriched acid-sorbing phase;
- (b) separating the acid-depleted aqueous feedstream from the acid-enriched acid sorbing phase;
- (c) contacting the separated acid-sorbing phase with an aqueous solution of trimethylamine, thereby solubilizing said carboxylic acid from the sorbing phase into said aqueous solution as trimethylammonium carboxylate, and forming a carboxylic-acid lean acid-sorbing phase;
- (d) separating the aqueous solution of trimethylammonium carboxylate from the acid-lean acid-sorbing phase;
- (e) treating the aqueous solution of trimethylammonium carboxylate to decompose the trimethylammonium carboxylate to yield the carboxylic acid and the trimethylamine;
- and
- (f) recovering the carboxylic acid yielded in step (e).
Dependencies are inferred from the claim text.