Multilayer oxide coated valve metal electrode for water purification
First Claim
1. An electrode comprisinga valve metal substrate, a protective precoat layer containing at least one substance selected from the class consisting of the platinum group metals and the oxides of platinum group metals, and an outermost semiconductive metal oxide layer, wherein the improvement consists of further providing an intermediate layer with a composition selected to decrease leakage of current from an electrolyte solution in contact with said electrode directly to said protective precoat layer when said electrode is anodically polarized, whereby said electrode is able to more efficiently oxidize organic substances dissolved in said electrolyte solution;
- for example, diethyleneglycolmonobutylether.
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Abstract
An electrode with large active surface area is made by winding a Ti-fiber tow around a rectangular Ti-plate, and an electrocatalytic coating of three layers is applied. A precoat comprising a mixture of iridium dioxide and tantalum pentoxide is applied first, using a solution of the corresponding chloride salts in hydrochloric acid with some nitric acid added to inhibit corrosion of the metal. A sealing coat is then applied, comprising tin dioxide doped with antimony, in order to improve adhesion of the final oxide coat to the precoat. The third and final coat comprises particles of titanium dioxide doped with niobium in the +4 oxidation cemented with titanium dioxide that is doped with antimony. Anodes of this description are preferably assembled together with corrosion resistant cathodes in an alternating sequence, with a plastic coated fiber glass mesh placed between the anodes and cathodes to prevent short circuiting. When a sufficiently large voltage is applied across the cell, organic substances dissolved in the electrolyte will be oxidized.
42 Citations
12 Claims
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1. An electrode comprising
a valve metal substrate, a protective precoat layer containing at least one substance selected from the class consisting of the platinum group metals and the oxides of platinum group metals, and an outermost semiconductive metal oxide layer, wherein the improvement consists of further providing an intermediate layer with a composition selected to decrease leakage of current from an electrolyte solution in contact with said electrode directly to said protective precoat layer when said electrode is anodically polarized, whereby said electrode is able to more efficiently oxidize organic substances dissolved in said electrolyte solution; - for example, diethyleneglycolmonobutylether.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
Specification