US1408364A

US1408364A - Manufacture of perborates

Info

Publication number: US1408364A
Application number: US356650A
Authority: US
Inventors: Langhard Johann Konrad
Original assignee: FREDRIKSSTAD ELEKTROKEMISKE FA
Current assignee: FREDRIKSSTAD ELEKTROKEMISKE FA; FREDRIKSSTAD ELEKTROKEMISKE FABRIKER AS
Priority date: 1919-03-04
Filing date: 1920-02-06
Publication date: 1922-02-28
Anticipated expiration: 1939-02-28
Also published as: FR508276A; GB139753A

Description

' No Drawing.

UNITED STATES PATENT OFFICE.

JOHA NN KONRAD LANGHARD, OF FREDRIKSSTAD; NORWAY, ASSIGN'ORTO FRED- I RIKSSTAD ELEKTROKEMISKE FABRIKER A/S, OF FREDRIKSSTAD, NORWAY.

MANUFACTURE OF PERBQRA'IES.

To all w from it may 0072 06m Be it known that I, JOHANN KoNRAD LANGHARD, a citizen of Switzerland, residing at Fredriksstad, Norway, have invented certain new and useful Improvements in the Manufacture of Perborates; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the manufacture of perborates by the electrolysis of aqueous borate solutions and has for its object an improved method of treating the electrolyzed solution.

A known method of producing sodium,

perborate electrolytically.consists in electrolyzing a solution containing borax and soda (sodium carbonate).

In this process the sodium carbonate is gradually neutralized to bicarbonate in proportion to the formation of perborate.

The reactions taking place may be illustrated by the equation:

It has been ascertained that it is of importance to reconvert the resulting bicarbonate into carbonate in order to attain an advantageous current output. This may be effected by means of caustic alkali (NaOH) or lime.

It is an important condition of a satis factory output, however, that the substances referred to are introduced in a state in which they are practically free from catalyzers. To use chemically pure hydroxide of sodium is of course not practicable, while on the other hand the commercial product usually contains small quantities of iron or even manganese compounds. The same applies also to lime. Under these conditions the industrial value of the process is rather questionable. The present invention has for its object a process whereby the difiiculties re ferred to are eliminated by simple and suitable means.

According to the invention the electrolyzed solution is treated with a peroxide instead of the hitherto employed substances, caustic soda or lime. Sodium peroxide is manufactured in a very pure condition practically free from injurious constituents and Specification of Letters Patent. Patented Feb. 28, 1922. Application filed Febrnary G, 1920. Serial No. 356,650.

when added to the electrolyzed solution it will have no disadvantageous influence upon the result. l

The action of the sodium peroxide may be illustrated by the following equation:

The addition of the peroxide also results in the formation of additional quantities of perborate as shown by the equation.

Experiments have proved that the precipitation of perborate by the addition of the peroxide is much more abundant than that obtained by cooling the electrolyte. The advantages of the described process and its practical value are obvious.

Example: A hundred liters of an aqueous solution containing 40 g. boraX, 100 g. soda, 7 g. perborate of sodium in the litre, and which may consist of the mother liquor from a previous operation is subjected to electrolysis in a suitable apparatus with a current strength of for instance 120 amp. during for instance 4 hours. During the electrolysis the content of perborate will increase for instance to 12 g. of perborate in the litre. without crystallization taking place. At the same time an equivalent quantity of sodium bicarbonate has been formed. To the liquid is now added sodium peroxide in a quantity of for instance g. This addition of sodium peroxide on the one hand effects regeneration of carbonate and on the other hand results in such an increase in the percentage of perborate, that percipitation of sodium perborate will begin. After some hours the crystallization of sodium perborate will be finished, without any considepable cooling of the liquid having taken ace.

p The solution can now be subjected to electrolysis for the production of further quantities of perborate, it may be after having been supplied with an additional quantity of borax.

The described treatment of the solution is suitably carried into effect in a separate ves sel into which the solution is conveyed from the electrolytic cells. When the precipitated perborate has been separated from the solution, this latter can be introduced into an electrolytic cell for further treatment.-

Claims 1. Process for the manufacture of sodium perborate, comprising in combination the steps of electrolyzing a solution containing hora-xand soda and adding sodium peroxide to the electrolyzed solution.

2. Process for the manufacture of sodium perborate comprising the steps of subjecting a solution containing borax and soda toel'ec trolysis, adding sodium peroxideto the elec trolyzed solution, separating the precipitated presence of two subscrlbmg witnesses.

sodium perborate from the solution and subjecting thesolution to electrolysis.

3. In a process of manufacturing sodium perborate, which consists in electrolyzing a solution containing borax and sodium car,-

solution, thereby increasing the yield in sodium perborate and regenerating the solution in sodium carbonate. g V

In testimony that I claim the foregoing as my invention, I have signed my name in JOHANN KONRAD LANGHARD. l Vitnesses:

NATE. A. HEDENsoi-IoN, R BERT H. FRAZTER;