US867320A - Electrolytic process and product. - Google Patents

Description

UNITED STATES PATENT OFFICE.

CLINTON PAUL TOWNSEND, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR T0 ELMER A. SPERRY, OF BROOKLYN, NEW YORK.

ELECTROLYTIC PROCESS AND PRODUCT.

Specification of Letters Patent.

Patented Oct. 1, 1907.

Application filed April 24,1905. Serial No. 257,273. 7

from the commercial monoxid of lead as heretofore known.

If a solution of sodium acetate or other alkali metal salt which is capable of yielding a solvent for lead' at the anode by electrolytic decomposition be electrolyzed between electrodes of lead, a solution of acetate or other salt of lead is formed at the anode, while at the cathode the hydroxid of the alkali metal is produced in equivalent quantity. This alkali metal hydroxid reacts with the lead salt to form a white amorphous precipitate of lead hydroxid, the sodiiim acetate or equivalent salt employed as an electrolyte being simultaneously regenerated.-

I have discovered that by suitably modifying the above conditions a characteristic crystalline product may be obtained, said product consisting substantially of lead oxid, PbO, instead of the hydrate obtained as above described. A preferred mode of carrying out the process is as follows: An electrolytic cell having an anode of lead and any suitable cathode is subdivided by a diaphragm which is substantially impermeable as a filter. The diaphragm may conveniently consist of parchment paper, and the cathode compartment may advantageously be of relatively small capacity.- The anolyte-consists initially of a solution of sodium acetate of convenient concentration: the initial catholyte may be sodium acetate, water, or preferably a solution of sodium hydroxid.. In any case sodium hydroxid accumulates in the cathode compartment until a defi- 1 appear in the anolyte, these crystals or crystalline aggregates having usually the form of thin plates having opposite reentrant angles.

The lead anode dissolves substantially in accordance with the current and its surface remains free from an adherent deposit. sired, whereby the potential difference for a given our- The solution may be heated if de- Portions of the electrolyte carrying the yellow crys- I talline product in suspension may be withdrawn continuously from the 'cell, the crystals separated by a filter press or by suitable settling and separating devices, and the clear solution returned to the cell. The product may then bewashed with water and dried at about 100 C. The dry product so obtained is found to consist substantially of lead and oxygen and tocorrespond substantially to the formula PbO. It is to a slight extent acted upon by water with the formation of lead hydroxid, and the product, after washing with Water and drying at 100 C. as above described, usually yields small proportions of moisture upon ignition. Small quantities of carbon dioxid are also usually evolved.

The product of the electrolysis consists initially of thin plates as above described, and although crystalline isvery smooth to the touch. The product dried at coniparatively low temperature, as 100 0., possesses peculiar physical properties, especially inthat it darkens rapidly under the influence of light and that the crystalline plates initially formed are subject to rapid disintegration. The product is further characterized by its tendency to hydrate in presence of water, acids or salts, a property which is highly advantageous as rendering it very quickly soluble even in dilute acids: in this respect it is sharply distinguished from ordinary litharge.

If the crystalline product be heated to a temperature considerably above 100 0., and preferably to low redness, it is found to differ in several important respects from the product dried at 100 C. and to approach more nearly in properties the monoxid of lead as heretofore known; thus it is no longer darkened by exposure to light, and it exhibits little or no tendency to become hydrated in presence of water or aqueous solutions. It

dissolves readily, however, in the usual solvents for and to simultaneously regenerate the electrolyte in ac-' I do not limit myself to the use of a diaphragm as above described nor to the particular solutions or conditions above mentioned as suitable.

The essential feature of the process consists in effecting a reaction between two compounds of lead, the lead constituting the base of one compound and constituting a part oi the acid radical of the other compound.

By suitably modifying the concentration oi the solutions and other conditions the oxid of lead may be obtained informs other than the yellow crystalline plates above described; for instance, I have thus been able to obtain a red precipitate consisting of minute aggregates of nearly spherical form, I do not, therefore, limit the process to conditions under which the lead oxid is produced-in any particular physical form.

I claim:

1. The method of producing lead oxid which consists in decomposing a suitable electrolyte with an anode of lead and producing compounds in which lead occurs in the basic and acid radicals respectively, and effecting a reaction be tween said compounds, substantially as described.

2. The method of producing lead oxid which consists in decomposing an alkali-metal acetate solution with an anode of lead and producing compounds in which lead occurs in the basic and acid radicals respectively, and effecting a reaction between said compounds, substantially as described.

3. The method of producing lead oxid which consists in passing an electric current from an anode of lead through a suitable electrolyte and diaphragm and producing compounds in which lead occurs in the basic and acid radicals respectively, and efiecting a reaction between said compounds, substantially as described.

4. The method of producing lead oxid which consists in passing an electric current from an anode of lead through an alkali-metal acetate solution and producing compounds in which lead occurs in the basic and acid radicals respectively, and elfecting a reaction between said compounds, substantially as described.

5. The method of producing lead oxid which consists in passing an electric current from an anode of lead through an alkaltmetal acetate solution and diaphragm and producing compounds in which lead occurs in the basic and acid radicals respectively, and effecting a reaction between said compounds, substantially as described 6. The method of producing lend oxid, which consists in efiecting a reaction between compounds in which lead oc curs in the basic and acid radicals respectively, substantially as described.

7. The method of producing lead oxid, which consists in eifecting a reaction between a plumbiie and a soluble salt of lead, substantially as described.

8. The method of producing lead oxid, which consists in efiecting a reaction between a pluinbite and lead acetate, substantially as described.

9. The method of producing lead oxid which consists in passing an electric current from an anode of lead through a suitable electrolyte, and causing the anode and cathode products to react under such conditions as to produce lead oxid, substantially as described.

10. The method of producing lead oxid which consists in passing an electric current from an anode of lead through a suitable electrolyte and diaphragm, and permitting the cathode product to return to the region of the anode at such rate as to produce lead oxid, substantially as described.

11. The method ofprodueing lead oxid, which consists in electrolytically dissolving lead and precipitating lead monoxid, substantially as described.

12. The method of producing lead oxid, which consists in electrolytically dissolving lead, precipitating lead monoxid, and heating the precipitate, substantially as described.

13. The herein described electrolytic product consisting substantially of lead and oxygen in atomic proportions, ex isting initially as yellow crystals, darkening by exposure to light, and readily hydrated.

14. The herein described electrolytic product consisting substantially of lead and oxygen in atomic proportions, existing initially as yellow crystalline plates haw ing opposite reentrant angles, darkening by exposure to light, and readily hydrated.

Witnesses:

EUGENE A. Brnwns, JULIA B. HILL.