Apparatus and method for urea electrolysis with controlled alkalinity
AssigneeThe United States of America as represented by the Secretary of the Army
InventorDavid R. Baker
Life of this patent
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Abstract
Apparatus and method for electrolysis of urea is capable of removing urea from waste-water generated by human urine or agricultural run-off while simultaneously producing cleaner water and hydrogen gas. The apparatus and method employ at least one water reduction electrode located close to at least one urea oxidation electrode. The water reduction electrode operates to generate a locally high pH such that the urea oxidation electrode operates in a locally high pH envelope where it can perform its reaction efficiently to break down the urea with little or no impact on the pH of the bulk solution.
Claims18
An apparatus for removing or eliminating urea from an aqueous solution, the apparatus comprising:
- at least one reactor cell having an interior capable of containing a quantity of the aqueous solution;
- at least one urea oxidation electrode disposed in the interior of the reactor cell;
- at least one water reduction electrode disposed in the interior of the reactor cell, the water reduction electrode being configured to produce hydroxide anions at least in the aqueous solution in a first volume in the reactor cell at least when the reactor cell contains the aqueous solution and is in operation;
- at least one counter electrode positioned so as to be in contact with a second volume configured to contain at least a portion of the aqueous solution, the aqueous solution in the second volume being in fluid communication with the aqueous solution in the first volume in the reactor cell when the apparatus is supplied with the aqueous solution;
- and
- at least one power supply configured to apply one or more voltages between the counter electrode and the water reduction electrode, and between the urea oxidation electrode and the counter electrode,
- wherein the first volume is in contact with at least a portion of the urea oxidation electrode such that the aqueous solution in the first volume is in contact with at least the portion of the urea oxidation electrode, wherein the urea oxidation electrode and the water reduction electrode are arranged in sufficiently close proximity such that the action of the water reduction electrode produces a hydroxide anion concentration in the aqueous solution in the first volume, and the hydroxide anion concentration is sufficiently high, in the aqueous solution in the first volume, in order for a process for urea removal from the aqueous solution to proceed when the apparatus is in operation.
An apparatus for removing urea from an aqueous solution, the apparatus comprising:
- a container having an interior and being configured to maintain a reaction environment comprising a quantity of the aqueous solution;
- at least one urea oxidation electrode disposed in the interior of the container;
- at least one water reduction electrode disposed in the interior of the container, the water reduction electrode being configured to produce a hydroxide anion concentration in a volume containing a portion of the aqueous solution, wherein the apparatus is configured to provide for the aqueous solution in the volume to be in contact with at least a portion of the urea oxidation electrode;
- at least one counter electrode disposed in the interior of the container for maintaining a charge balance with currents passing at the water reduction electrode and the urea oxidation electrode;
- and
- at least one power supply configured to apply one or more voltages between the counter electrode and the water reduction electrode and between the urea oxidation electrode and the counter electrode,
- wherein the concentration of hydroxide anions is sufficiently high in the aqueous solution in the volume contacting at least the portion of the urea oxidation electrode such that urea removal from the aqueous solution, by electrolytic breakdown of urea, proceeds at a sufficiently high rate as to be practically useful when the apparatus is in operation.
Dependencies are inferred from the claim text.