US2589982A - Electrolytic production of ammonium persulfate solutions - Google Patents

Electrolytic production of ammonium persulfate solutions Download PDF

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US2589982A
US2589982A US25984A US2598448A US2589982A US 2589982 A US2589982 A US 2589982A US 25984 A US25984 A US 25984A US 2598448 A US2598448 A US 2598448A US 2589982 A US2589982 A US 2589982A
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diaphragm
catholyte
cell
cathode
acid
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US25984A
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Wood William Stanley
Clennett George
Hulland Hubert Leslie
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LA PORTE CHEMICALS Ltd
PORTE CHEMICALS Ltd
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PORTE CHEMICALS Ltd
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    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00Electrolytic production of inorganic compounds or non-metals
    • C25B1/01Products
    • C25B1/28Per-compounds
    • C25B1/29Persulfates

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  • This invention relates to a process for the manufacture of acid solutions of ammonium persulphate by electrolysis using electrolytic cells having a-stationary catholyte. Such solutions can be hydrolysed and distilled to yield hydrogen peroxide or treated to give ammonium persulphate crystals.
  • the present invention provides a process for the manufacture of acid solutions of ammonium persulphate by the electrolysis of acid solutions of ammonium sulphate using an electrolytic cell having a stationary catholyte 'whereinthe catholyte i maintained acid in reaction throughout the electrolysis and wherein the cathode is surrounded by a closely spaced porous ceramic diaphragm.
  • Fig. 1 shows a longitudinal sectional view of the cell and Fig. 2 shows a plan view of part of the cell.
  • the cell I contains a plurality of cathodes 2 screwed into a bar 3 of the cell, each cathode being surrounded by a closely fitting porous ceramic diaphragm 4.
  • the anodes 5 are disposed in the anolyte 6 the level of which is indicated at I.
  • the anolyte solution is led into the cell I through an inlet pipe 8 and discharges through an overflow pipe 9.
  • A. preferred embodiment of this invention for the manufacture of acid solutions of ammonium persulphate comprises electrolysing and acid soof the diaphragm is between 10 and 40. mls. per
  • the acid solution of ammonium persulphate obtained may be hydrolysed and distilled to give hydrogen peroxide or it may be converted into ammonium persulphate crystals in ways well known to those skilled in the art.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)

Description

March 18, 1952 w. s. WOOD ETAL 2,589,932
ELECTROLYTIC PRODUCTION OF AMMONIUM PER-SULFATE SOLUTIONS Filed May 8, 1948 M1. LIAM sr/m/z E) W000 GEORGE C1. E/V/VETT #05527 LESL/E HULL/7N0 Patented Mar. 18, 1952 ELECTROLYTIC PRODUCTION OF AMMO- NIUlW PERSULFATE SOLUTIONS William Stanley Wood, Harpenden, and George Clennett and Hubert Leslie Hulland, Luton, England, assignors to La Porte Chemicals Limited, Luton, England, a British company Application May 8, 1948, Serial No. 25,984 In Great Britain May 12, 1947 2 Claims.
This invention relates to a process for the manufacture of acid solutions of ammonium persulphate by electrolysis using electrolytic cells having a-stationary catholyte. Such solutions can be hydrolysed and distilled to yield hydrogen peroxide or treated to give ammonium persulphate crystals.
In the electrolytic conversion of acid solutions of ammonium sulphate to ammonium persulphate it is usual to surround the cathode with a diaphragm to prevent the ammonium persulphate formed being decomposed and to obtain the maximum current efiiciency. Such diaphragms are made of .porous ceramic material, of asbestos, of microporous ebonite, or other suitable material. It is possible in this electrolysis to use cells having separate chambers for anolyte and catholyte both of which flow continuously through the cell. With such an arrangement the catholyte is always acid in reaction but this involves controlling and handling two separate flows of electrolyte through the cell with consequent multiplicity of plant and controls. It is therefore advantageous to employ a single chamber cell in which the catholyte is stationary while only the anolyte is discharged continuously.
In the type of process using a stationary catholyte .a porous ceramic diaphragm is used and, as stated above, the anolyte flows continuously through the cell, eventually being discharged as an acid solution of ammonium persulphate, while the catholyte remains in the diaphragm chamber and is therefore stationary. The diaphragms heretofore used have been very loosely fitting so that there is always a considerable volume of stationary catholyte in the diaphragm. As the electrolysis progresses the concentration of ammonium ions in this stationary cat'holyte increases and this increase in ammonium ions eventually results in an alkaline condition in the catholyte. This alkaline catholyte has an increased electrical resistance thus increasing the resistance. This problem of attack cannot be solved by altering the composition of the ceramic alkaline solutions.
material as it has not yet been found possible to manufacture ceramic diaphragm material which is simultaneously resistant to both acid and This increased resistance of catholyte and diaphragm causes an increase in the potential difference across the cell leading to an increased consumption of electrical energy per potential difference across the cell. Also the alkaline condition of the catholyte results in? the precipitation of the oxides of the metallic impurities present in the solution. This precipitation occurs in the body of the diaphragm at the alkali-acid interface and "results in the blocking up of the pores of the diaphragm with a consequent increase in the resistance of the diaphragm. A further disadvantage resulting from this alkaline catholyte is that this alkaline solution attacks the ceramic diaphragm material causing it to break down so that the pores beu come blocked which again'leads toan increase in temperature.
unit of ammonium persulphate produced, as well as to an increase in the amount of cooling re quired to maintain the cell at its eificient working A further consequence is the loss of ammonia from the system owing to its evolution from the alkaline catholyte.
I It has now been found according to this invention that the above disadvantages of using ceramic diaphragms with a stationary catholyte can be obviated if the liquid within the diaphragm is always maintained acid in reaction and if a closely spaced porous ceramic diaphragm is used.
Accordingly, the present invention provides a process for the manufacture of acid solutions of ammonium persulphate by the electrolysis of acid solutions of ammonium sulphate using an electrolytic cell having a stationary catholyte 'whereinthe catholyte i maintained acid in reaction throughout the electrolysis and wherein the cathode is surrounded by a closely spaced porous ceramic diaphragm.
Preferably platinum anodes and graphite cathodes are employed. A cell suitable for carrying out the process of the present invention is shown in the accompanying drawings in which Fig. 1 shows a longitudinal sectional view of the cell and Fig. 2 shows a plan view of part of the cell.
Referring to the drawings, the cell I contains a plurality of cathodes 2 screwed into a bar 3 of the cell, each cathode being surrounded by a closely fitting porous ceramic diaphragm 4. The anodes 5 are disposed in the anolyte 6 the level of which is indicated at I. The anolyte solution is led into the cell I through an inlet pipe 8 and discharges through an overflow pipe 9.
- It has been found that the best results are obtained when the distance between the cathode and inner surface of the diaphragm does-not exceed 3 mm. at any point.
In order to achieve the desired conditions of continuous acidity in the diaphragm coupled with a low potential difference across the cell togcther with maximum energy efficiency it was found. that the leakage of electrolyte through the porous diaphragm-material had tobe within certain limits in order that there was sufficient flow of acid electrolyte into the diaphragm to maintain the catholyte acid in reaction. The factors which affect this leakage are the permeability of the ceramic diaphragm material and the depth of electrolyte outside the diaphragm. The depth of liquid outside the dia-- phragm when it is placed in the cell is referred to herein as the working level of the diaphragm. An increase in the permeability of the ceramic material or an increase in the working level of the diaphragm with fixed permeability both lead to an increasedleaka'geofelectrolyte through the diaphragm, and these two factors must be varied to obtainthe desired leakage. We measure the permeability of 4 the diaphragm as follows: The leakage is expressed as the amount of water which can flow to air through unit area of the diaphragm per minute.
It was found that the limits of leakage for a suitable porous ceramic diaphragm lay between I and mls. of water per sq. dm. per minute when it is filled to its working level with water.
In order to achieve the desired electrolysis conditions it was also found preferable to limit the current density to a figure between 3 and 12 amps per sq. dm. at the cathode.
A. preferred embodiment of this invention for the manufacture of acid solutions of ammonium persulphate comprises electrolysing and acid soof the diaphragm is between 10 and 40. mls. per
minute when filled to the working level (measured as hereinbefore defined).
Under these conditions the stationary catholyte remains continuously acid and ammonium persulphate solutions are produced with an improved energy efiiciency, no ammonia is lost from the system and the condition and life of the diaphragm are greatly improved. Also such an arrangement of closely spaced ceramic diaphragms is very economical in space for the general electrode assembly which is capable of easy multiplication for the construction of large units.
As indicated above the acid solution of ammonium persulphate obtained may be hydrolysed and distilled to give hydrogen peroxide or it may be converted into ammonium persulphate crystals in ways well known to those skilled in the art.
As mentioned above, a number of advantages result from the employment of a catholyte which is continuously acid in reaction. Thus, the ohmic resistance of catholyte and diaphragm, and hence the potential difference across the cell, is reduced. A high current efficiency is obtained together with a high yield per unit of electrical energy. There is no alkali build up in the catholyte and hence no blocking up of the pores of the diaphragm with consequent disinteg'ration- The following example illustrates how the process of the invention may be carried into effect:
An acid solution of ammonium sulphate having the following composition: 200 gms./litre (NH4)2SO4- and 300 gms./litre H2SO4, was electrolysedi'n a cell having platinum anodes and a.
carbon cathode surrounded by a porous ceramic diaphragm, 36 mm. outer diameter, 1.5 mm. wall thickness, having a leakage to air of 80 cc./min. of water when filled with water to its working level of 50 cms. and the distance between the ceramic diaphragm and the carbon cathode was 2 mm. The current was 30 amps on the cathode, i. e., about 6 amps per sq. dm. Throughout the electrolysis it was found that the catholyte continuously showed an acid reaction. The potential difference across the cell was 4.9 volts. The energy efiiciency was 0.85 kWh/lb. of ammonium persulphate when the concentration of the ammonium persulphate solution produced was 260 gms./litre. After the cell had been running continuously for 12 months the diaphragm was strong and in good condition and the original leakage was unimpaired showing that there had been no blockage of the pores.
. -We claim:
1. In the manufacture of solutions of. ammonium persulphate by electrolysis carried on in a diaphragm cell wherein a substantially stationary body of catholyte is maintained on the cathode side of said diaphragm with the diaphragm spaced from said cathode a substantial distance butnot exceeding 3 mm., the improvement which comprises subjecting an acid solution of ammonium sulphate as anolyte to electrolysis in said cell while causing a leakage of said anolyte through said diaphragm to the catholyte side thereof sufficient to maintain the oatholyte acid in reaction during the course of the electrolysis, and maintaining a current density of between 3 and 12 amps. per sq. dm. of the immersed surface of said cathode.
2. In the manufacture of solutions of ammonium persulphate by electrolysis carried on in a porous ceramic diaphram cell wherein a substantially stationary body of catholyte is maintained on the cathode side of said diaphragm and the cathode is spaced from the diaphragm a substantial distance but not exceeding 3 mm., the improvement which comprises subjecting an acid solution of ammonium sulphate as anolyte to electrolysis in said cell at a current density on the cathode of between 3 and 12 amps. per sq. dm. while causing a leakage of said anolyte through said diaphragm to the catholyte side thereof during the course of the electrolysis equivalent to a leakage of water to air of from 10 to 40 mls. per sq. dm. per minute when a diaphragm of like porosity is filled to the working level with water.
WILLIAM STANLEY l/VOOD. GEORGE CLENNETT. HUBERT LESLIE HULLAND.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,059,809 Adolph et al Apr. 22, 1913 1,907,812 Honsberg May 9, 1933 2,094,384 Tucker et a1 Sept. 28,1937- 2,281,090 Salleras Apr. 28, 1942 2,349,998 Trinius May 30, 1944 2,392,868 Stuart Jan. 15,v 1946 FOREIGN PATENTS Number Country Date 508,524 Great Britain July 3, 1939 510,429. 1 Great Britain Aug. 1, 1939

Claims (1)

1. IN THE MANUFACTURE OF SOLUTIONS OF AMMONIUM PERSULPHATE BY ELECTROLYSIS CARRIED ON IN A DIAPHRAGM CELL WHEREIN A SUBSTANTIALLY STATIONARY BODY OF CATHOLYTE IS MAINTAINED ON THE CATHODE SIDE OF SAID DIAPHRAGM WITH THE DIAPHRAGM SPACED FROM SAID CATHODE A SUBSTANTIAL DISTANCE BUT NOT EXCEEDING 3 MM., THE IMPROVEMENT WHICH COMPRISES SUBJECTING AN ACID SOLUTION OF AMMONIUM SULPHATE AS ANOLYTE TO ELECTROLYSIS IN SAID CELL WHILE CAUSING A LEAKAGE OF SAID ANOLYTE THROUGH SAID DIAPHRAGM TO THE CATHOLYTE SIDE THEREOF SUFFICIENT TO MAINTAIN THE CATHOLYTE ACID IN REACTION DURING THE COURSE OF THE ELECTROLYTSIS, AND MAINTAINING A CURRENT DENSITY OF BETWEEN 3 AND 12 AMPS. PER SQ. DM. OF THE IMMERSED SURFACE OF SAID CATHODE.
US25984A 1947-05-12 1948-05-08 Electrolytic production of ammonium persulfate solutions Expired - Lifetime US2589982A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3406108A (en) * 1965-04-28 1968-10-15 Fmc Corp Regeneration of spent ammonium persulfate etching solutions
US4127456A (en) * 1976-12-23 1978-11-28 Fmc Corporation Polarizer for the electrolytic production of peroxydisulfates
US4626327A (en) * 1985-06-06 1986-12-02 Fmc Corporation Electrolytic process for manufacturing potassium peroxydiphosphate
CN102828197A (en) * 2012-08-31 2012-12-19 云浮市银利化工有限公司 Full-sealed type ammonium persulfate electrolysis system and method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3051611A (en) * 1959-11-16 1962-08-28 Cubano Inst Invest Hydrolysis of bagasse

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1059809A (en) * 1910-10-06 1913-04-22 Gustav Adolph Manufacture of persulfates.
US1907812A (en) * 1929-02-05 1933-05-09 Ig Farbenindustrie Ag Electrolytic cell
US2094384A (en) * 1934-11-12 1937-09-28 Du Pont Electrolysis apparatus and process
GB508524A (en) * 1938-01-03 1939-07-03 Robert Christian Cooper Electrolytic manufacture of persulphuric acid and its salts
GB510429A (en) * 1938-02-01 1939-08-01 Carl Trinius An improved process for obtaining persalts, e.g. persulphates by electrolysis
US2281090A (en) * 1937-03-31 1942-04-28 Buffalo Electro Chem Co Electrolytic manufacture of potassium persulphate
US2349998A (en) * 1938-02-01 1944-05-30 Trinius Werner Apparatus for obtaining persalts by electrolysis
US2392868A (en) * 1942-05-04 1946-01-15 Hooker Electrochemical Co Electrolytic alkali halogen cells

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1059809A (en) * 1910-10-06 1913-04-22 Gustav Adolph Manufacture of persulfates.
US1907812A (en) * 1929-02-05 1933-05-09 Ig Farbenindustrie Ag Electrolytic cell
US2094384A (en) * 1934-11-12 1937-09-28 Du Pont Electrolysis apparatus and process
US2281090A (en) * 1937-03-31 1942-04-28 Buffalo Electro Chem Co Electrolytic manufacture of potassium persulphate
GB508524A (en) * 1938-01-03 1939-07-03 Robert Christian Cooper Electrolytic manufacture of persulphuric acid and its salts
GB510429A (en) * 1938-02-01 1939-08-01 Carl Trinius An improved process for obtaining persalts, e.g. persulphates by electrolysis
US2349998A (en) * 1938-02-01 1944-05-30 Trinius Werner Apparatus for obtaining persalts by electrolysis
US2392868A (en) * 1942-05-04 1946-01-15 Hooker Electrochemical Co Electrolytic alkali halogen cells

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3406108A (en) * 1965-04-28 1968-10-15 Fmc Corp Regeneration of spent ammonium persulfate etching solutions
US4127456A (en) * 1976-12-23 1978-11-28 Fmc Corporation Polarizer for the electrolytic production of peroxydisulfates
US4626327A (en) * 1985-06-06 1986-12-02 Fmc Corporation Electrolytic process for manufacturing potassium peroxydiphosphate
CN102828197A (en) * 2012-08-31 2012-12-19 云浮市银利化工有限公司 Full-sealed type ammonium persulfate electrolysis system and method
CN102828197B (en) * 2012-08-31 2014-12-10 云浮市银利化工有限公司 Full-sealed type ammonium persulfate electrolysis system and method

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GB627648A (en) 1949-08-12
FR966125A (en) 1950-10-02
NL69507B (en)
DE834093C (en) 1952-03-17
BE482416A (en)

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