Alliedsignal Inc.

Allied Corporation

Yu-Chih Chiao

Frederick P Chlanda

Krishnamurthy N Mani

Carolyn Byszewski

Krishnamurthy Nagasubramanian Mani

Frederick Paul Chlanda

The present invention is an improved process for electrodialytically generating salts of volatile acids and/or bases from a salt stream. The salt of the volatile base may either be generated from a similar salt, or may be recovered from a mixed salt solution containing the salt of a volatile base and other similar salts. The salt solution is treated in a two or three compartment electrodialytic water splitter. The acid formed in the acid compartment of the electrodialytic unit is neutralized as it is formed by adding the volatile base directly to the acid loop. Neutralization of the acid in the acid loop minimizes the acid concentration in the electrodialytic unit, thereby increasing the efficiency of the membranes, and the cell stack. The electrodialytic unit may be run in either batch or continuous mode.

Separation/recovery of ammonium salts via electrodialytic water splitting

The present invention relates to a method and an apparatus of electodialytically treating an acid such as citric acid to produce a desired salt of the anion of the acid, such as sodium citrate. A cation can be introduced into a solution via a cheap donor salt solution such as NaCl or KCl, without significantly altering or degrading the purity of the final product. The apparatus comprises a three-compartment cell, which comprises at least two adjacent anion selective membranes to accomplish a cation substitution reaction exploiting the differential selectivities of the adjacent anion membranes employed.

Method to produce sodium citrate using electrodialysis

A method of separating acid from an aqueous feed stream comprising acid and salt. The method is conducted in an apparatus comprising a bipolar membrane between at least one first anion membrane and at least one second anion membrane.

Method for purification of acids from materials comprising acid and salt

The present invention is a method of recovery of base from material comprising base or acid and salt. The method is conducted in an apparatus comprising a cation membrane between two bipolar membranes.

Method for purification of bases from materials comprising base and salt

The present invention is a method of recovery of base from material comprising base or acid and salts. The method is conducted in an apparatus comprising a cation membrane between two bipolar membranes.

We have discovered an improved, energy efficient method for recovering and regenerating acid from a solution comprising acid and salt. The process comprises of the steps of supplying a solution comprising salt and a first concentration of acid to a first compartment of an electrodialysis apparatus comprising a first compartment and a second compartment, supplying a liquid comprising water to the second compartment, applying a direct current to the electrodialysis apparatus to form, in the first compartment, a first product comprising salt and a second concentration of acid, the second concentration of acid being less than the first concentration of acid, and, in the second compartment, a second product comprising water and enriched in acid by a proportionate amount, recovering the first product, recovering the second product, recovering acid from the first product using electrodialytic water splitting to convert at least a portion of the salt to a third product comprising acid, and recovering the third product. The process has particular utility for the recovery and regneration of mixed acids from spent pickle liquors containing free nitric acid and salts of an anion other than nitrate anion.

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Bridgewater, NJ, United States of America

Yu-Chih Chiao