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US 6,787,021 B2Granted
Purification of onium hydroxides by electrodialysis
AssigneeSachem, Inc.
InventorsRobert J. Reiter, Kelly Hefner
Life of this patent
Estimating the term…
Abstract
This invention relates to a process for improving the purity of an aqueous onium hydroxide solution. In particular, the invention relates to a process for improving the purity of aqueous onium hydroxide solutions containing undesirable amounts of anions. The invention also relates to the improved high purity onium hydroxide solutions obtained by the above method.
Claims37
A process for improving the purity of an aqueous onium hydroxide solution which comprises:
- (A) providing an electrochemical cell comprising at least four compartments, said compartments being formed by a cathode, an anode, and in order from the anode to the cathode, a first bipolar membrane, a first cation selective membrane, and a second bipolar membrane, wherein the compartment adjacent to the cathode is formed by the second bipolar membrane and the cathode,
- (B) charging the onium hydroxide solution to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) passing a current through the cell, and
- (D) recovering a purified onium hydroxide solution from the recovery compartment formed by the first cation selective membrane and the second bipolar membrane.
1 more element
A process for improving the purity of an aqueous onium hydroxide solution which comprises:
- (A) providing an electrochemical cell comprising at least 5 compartments, said compartments being formed by an anode, a cathode, and in order from the anode to the cathode, a first bipolar membrane, a first cation selective membrane, a second cation selective membrane, and a second bipolar membrane,
- (B) charging the onium hydroxide solution to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) passing a current through the cell, and
- (D) recovering a purified onium hydroxide from the recovery compartment formed by the second cation selective membrane and the second bipolar membrane.
1 more element
A process for reducing the halide content of an aqueous quaternary ammonium hydroxide solution containing halide ions which comprises:
- (A) providing an electrochemical cell comprising at least four compartments, said compartment being formed by an anode, a cathode, and in order from the anode to the cathode a first bipolar membrane, a first cation selective membrane and a second bipolar membrane, wherein the compartment adjacent to the cathode is formed by the second bipolar membrane and the cathode,
- (B) charging the quaternary ammonium hydroxide solution containing a quantity of halide ion to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) charging an electrolyte to the other compartments,
- (D) passing a current through the cell, and
- (E) recovering an aqueous quaternary ammonium hydroxide solution from the recovery compartment formed by the first cation selective membrane and the second bipolar membrane, wherein the quaternary ammonium hydroxide recovered from the recovery compartment contains less halide ion than the amount of halide ion present in the quaternary ammonium hydroxide solution charged to the feed compartment.
2 more elements
A process for reducing the halide content of an aqueous quaternary ammonium hydroxide solution containing halide ions which comprises:
- (A) providing an electrochemical cell comprising at least 5 compartments containing water, said compartments being formed by an anode, a cathode, and in order from the node to the cathode, a first bipolar membrane, a first cation selective membrane, a second cation selective membrane, and a second bipolar membrane,
- (B) charging the quaternary ammonium hydroxide solution containing a quantity of halide ion to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) charging an electrolyte to the other compartments,
- (D) passing a current through the cell, and
- (E) recovering a quaternary ammonium hydroxide solution from the recovery compartment formed by the second cation selective membrane and the second bipolar membrane, wherein the recovered quaternary ammonium hydroxide solution contains less halide ion than the amount of halide ion present in the quaternary ammonium hydroxide solution charged to the feed compartment in step B.
2 more elements
A process for improving the purity of an aqueous onium hydroxide solution derived from the elution of onium cations absorbed on a cation exchange material with an aqueous solution of an inorganic base which comprises:
- (A) providing an electrochemical cell comprising at least four compartments, said compartments being formed by a cathode, an anode, and in order from the anode to the cathode, a first bipolar membrane, a first cation selective membrane, and a second bipolar membrane, wherein the compartment adjacent to the cathode is formed by the second bipolar membrane and the cathode,
- (B) charging the onium hydroxide solution to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) passing a current through the cell, and
- (D) recovering a purified onium hydroxide solution from the recovery compartment formed by the first cation selective membrane and the second bipolar membrane.
1 more element
A process for improving the purity of an aqueous onium hydroxide solution which comprises:
- (A) providing an electrochemical cell comprising at least 5 compartments, said compartments being formed by an anode, a cathode, and in order from the anode to the cathode, a first bipolar membrane, a first cation selective membrane, a second cation selective membrane, and a second bipolar membrane,
- (B) charging a onium hydroxide solution derived from the elution of onium salt absorbed on a cation exchange material with an aqueous solution of an inorganic base to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) passing a current through the cell, and
- (D) recovering a purified onium hydroxide from the recovery compartment formed by the second cation selective membrane and the second bipolar membrane.
1 more element
A process for reducing the halide content of an aqueous quaternary ammonium hydroxide solution containing halide ions which comprises:
- (A) providing an electrochemical cell comprising at least four compartments, said compartments being formed by an anode, a cathode, and in order from the anode to the cathode, a first bipolar membrane, a first cation selective membrane and a second bipolar membrane, wherein the compartment adjacent to the cathode is formed by the second bipolar membrane and the cathode,
- (B) charging a quaternary ammonium hydroxide solution derived from the elution of quaternary ammonium cations absorbed on a cation exchange material with an aqueous solution of an inorganic base and containing a quantity of halide ion to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) charging an electrolyte to the other compartments,
- (D) passing a current through the cell, and
- (E) recovering an aqueous quaternary ammonium hydroxide solution from the recovery compartment formed by the first cation selective membrane and the second bipolar membrane, wherein the quaternary ammonium hydroxide recovered from the recovery compartment contains less halide ion than the amount of halide ion present in the quaternary ammonium hydroxide solution charged to the feed compartment.
2 more elements
A process for reducing the halide content of an aqueous quaternary ammonium hydroxide solution containing halide ions which comprises:
- (A) providing an electrochemical cell comprising at least 5 compartments containing water, said compartments being formed by an anode, a cathode, and in order from the anode to the cathode, a first bipolar membrane, a first cation selective membrane, a second cation selective membrane, and a second bipolar membrane,
- (B) charging a quaternary ammonium hydroxide solution derived from the elution of quaternary ammonium cations absorbed on a cation exchange material with an aqueous solution of an inorganic base and containing a quantity of halide ion to a feed compartment formed by the first bipolar membrane and the first cation selective membrane, wherein the feed compartment is free of ion exchange material,
- (C) charging an electrolyte to the other compartments,
- (D) passing a current through the cell, and
- (E) recovering a quaternary ammonium hydroxide solution from the recovery compartment formed by the second cation selective membrane and the second bipolar membrane, wherein the recovered quaternary ammonium hydroxide solution contains less halide ion than the amount of halide ion present in the quaternary ammonium hydroxide solution charged to the feed compartment in step B.
2 more elements
Dependencies are inferred from the claim text.