Method and apparatus for producing hydrogen peroxide

Abstract

An electrolytic cell includes an electrode in a chamber including an electrolyte and an electrical power supply arranged to supply electrical energy to the electrode. A current sensor detects electrical current in the cell. A reservoir of a metal salt solution is provided. A controller is arranged to supply metal salt solution from the reservoir to the chamber of the cell in dependence on the current detected at the sensor. This permits the conductivity of the electrolyte to be brought up to required levels quickly, independently of dynamic cell conditions. Previously, metal salt was added gradually to the electrolyte. This was time-consuming and produced inconsistent results.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application is a national stage application under 35 USC 371 of International Application No. PCT / GB2007 / 001211, filed Apr. 2, 2007, which claims the priority of United Kingdom Application No. 0607272.2, filed Apr. 11, 2006, the contents of both of which prior applications are incorporated herein by reference.FIELD OF THE INVENTION[0002]This invention relates to apparatus for, and methods of, producing hydrogen peroxide by means of electrolytic cells, and especially to such apparatus arranged to produce hydrogen peroxide in, for example, an automatic dishwasher.BACKGROUND OF THE INVENTION[0003]In a conventional automatic dishwasher, detergents are employed to produce a wash liquid for use on dirty items placed in the dishwasher for washing. However, such detergents can decompose to produce pollutants when the wash liquid is released to the environment.[0004]It has been proposed to use a solution of hydrogen peroxide as a wash liquid in an ...

AI Technical Summary

Benefits of technology

[0009]The invention permits the conductivity of the electrolyte to be brought up to required levels quickly. Furthermore, the conductivity of the cell is controlled independently of conditions in the cell, such as changes in temperature and water quality.

Problems solved by technology

However, such detergents can decompose to produce pollutants when the wash liquid is released to the environment.

However, hydrogen peroxide is unstable and is not capable of being stored for long periods without decomposing.

A problem which may be encountered with the electrolysis of water is that, in order to produce good yields of hydrogen peroxide, the water must be electrically conductive.

However, ordinary tap water, which would be the most convenient source of water, is not particularly conductive.

However, gradual addition of sodium chloride to the electrolyte is time-consuming.

The addition of a predetermined amount of salt solution to the electrolyte may not produce the required conductivity, due to variations in water quality, temperature and dynamic cell conditions.

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