Ten ®Ft®El Gustav Adolph and Albert,Pietzsch, of Munich, Germany

TEN ®FT®EL GUSTAV ADOLPH AND ALBERT,PIETZSCH, OF MUNICH, GERMANY. MANUFACTURE OF PERSULFATES. 1,059,8U9. Speci?cation of‘Letters Patent. Patented Apr. 22, 1913. No Drawing’. Application ?led October 6, 1910. Serial N 0. 585,571.

To all whom, it may concern: . Beit known that we, GUSTAV ADoLPH and may be readily and simply converted into . ALBERT, Pm'rzsorr, ‘citizens of Germany, re persulfate of potassium, a sulfate-of-am "siding at Munich, Bavaria, Germany, have monium solution being obtained as one of invented certain new’ and useful Improve the byproducts of the reaction, from which 55 ments in the Manufacture of Persulfates; an ammonium-persulfate solution may be and we do hereby declare the following to readily obtained electrolyticallydirectly or be a full, clear, and exact description of the with the addition of sulfuric-acid. From invention, such as will enable others skilled this it will be seen that the manufacturer in‘ the art to which it appertains to make has it in his power to regenerate the am 60 and use the. same. . monium-persulfate continuously during the ~ process and as‘ the same is required. p This invention relates to the manufacture of persulfates of the. alkali-metals, and the Under the present invention potassium ‘ 'same is based on the utilization of persul persulfate is directly obtained from potas 15 fate of ammonium, such'as can be readily sium sulfate with as advantageous a utiliza 65 obtained by electrolytic methods, for this tion of the electric current as in the case purpose.‘ In‘ this art, the production of Where ammonium persulfate is obtained potassium-persulfate is at present carried‘ from‘ammonium sulfate. This new process is out either by directly preparing the same based on the fact that, as applicants have 20 electrolytically, or by the. conversion of am-v found, solutions of ammonium persulfate monium-persulfate.v The latter method has which has been obtained by known electro~ the advantage that. it takes as a starting lytic methods, may be directly acted on by product ammonium-persulfate which is. sulfate of potassium in solid formiand un . readily obtainable by electrolytic methods,‘ _ dissolved, in such a way that an ammonium 25 while. the potassium-persulfate" can only be sulfate remains in the solution. 75, obtained with difficulty and-with very poor The following example is given‘ for the yields. A disadvantage of the _ said method ' purpose of fully disclosing the invention: of starting with ammonium-persulfate, how Example 1: To an ammonium-persulfate, . ever, resides in the‘ fact that the, ammonium~ solution obtained. electrolytically, there is persulfate is?reacted on ‘by potassium-car added an equivalent amount of'potassium 80 bonate, a very costly reagent, and that there sulfate or of potassium-bisulfate in a after the ammonium-sulfate mustbe regener4 powdered or solid form, the mixture being > ated from the ‘ammonium carbonate by the vigorously agitated and gently heated. The . aid of sulfuric-acid. potassium~persulfate is‘immediately sepa 35 ‘rated from the solution in theform of ?ne 85 V The object of the present invention is to’ crystalline laminae orplates, and may be sep ' overcome the difficulty above pointed out, and arated by the usual methods, such as siphon with this object in view, the applicants have .ingvo?' liquid, by decanting, devised the present invention which is based centrifugal ac-_ on the discovery made by them, that potas tion, or otherwise. The remaining solu 40 sium-persulfate may ‘be direct-1y obtained tion of ammonium-sulfate, either in‘ the 90 neutralform or as bisulfate, can then‘ be re from, the sulfates of.potassium,.under which generated to ammonium-persulfate by sub— term are to be understood not only the neu-' vjecting the same ‘to electrolysis. tral sulfatesbut other sulfates, such as bi-‘ sulfateof potassium, said reaction proceed - The applicants have further found that 45 the conversion of ammonium-persulfate to 95 ing according tothe equatlonslz ’ ' potassium-persulfate can be carried out to particular advantage. when this is done in connection With the electrolytic action in the Leda-(Nessa electrolyzer, for which purpose ,a mixture of

'50 ammonium - sulfate and potassium - sulfate, 100 . under which terms are to be understood _ lthisimannerlithe,.iammoniumrpersulfate either .the neutral or bisulfates, is directly 1,059,809 utilized. Under these conditions, the am be separated by a diaphragm. After they 6.5 monium-persulfate is formed at the anode electrolyte has been saturated, with sodium- - ' with the usual. good yields, amounting, to persulfate, the latter begins to be precipid. . . 80% and upward. This freshly generated tated, the sodium-salt thus precipitated be ammonium-persulfate is, however, immedi ing replaced bysodium-bisulfate. .In order ' ately and at the moment of ‘its format-ion to more fully disclose this process the fol converted into potassium-persulfate and am lowing example may .serve :- p _ monium-sulfate by the reaction, of the potas Example 3: A solution of 500grams so sium-sulfate existing in the; bath or solution. dium-bisulfate together with 500 grams am-l 10 The potassium-persulfate thus formed‘ is monium-bisulfate is subjected 'to electrolysis thrown out in solid form. and “the am in a diaphragm electrolyzer provided with 75. monium-sulfate is then. again converted into platinum electrodes, sodium-bisulfate being the persulfate, under the action of the cur-_ continually ‘supplied to the anode space as rent. Under this method, of proceeding, it the reaction proceeds, while-the gases es is, therefore, only necessary to supply the caping from the cathode space are carried potassium-salt as fast as it is consumed, by over into anode, solution for the purpose. of additions of further quantities of potassium absorbing any ammonia, which might escape sulfate (neutral or bis'ulfate) in order to ob- ' from the acid ‘anode. solution. After’ a tain a continuous uninterrupted production period of time, sodium-persulfate ‘begins to- v be precipitated-in the anode space. The‘ 20 ofvery potassium-persulfate great advantage in with this high connection yields. is, ~yield under this process attains about ‘80%. ‘that the process may be carried out without It will be noted that the term sulfates the intervention of a diaphragm, for the rea as employed in the‘ claims includes not only son that practically no persulfate remains in ‘the neutral sulfates but also the bisulfates. 25' solution. The following example will serve What we claim and desire to secure by to more fully ‘disclose this modi?cation of Letters Patent is as follows: 1. The. process of obtaining a persulfate the process. ' , ~ ' Example 2: A solution of 200 grams of of an alkali-metal, which consists in caus-_ ammonium-bisulfate together, ' with 400 ing a sulfate of said alkali-metal in an un 30 grams of potassiunrbisulfate is subjected to dissolved state to react on a bath of am- . electrolysis in the ‘usual manner 1with the monium persulfate. ’ 95 aid of platinum electrodes and without the y 2. The process of obtaining a persulfate intervention of a diaphragm, the electrolyte of an alkali-metal, which consists in mixing remaining constantly in contact with solid ammonium sulfate in abath with a sulfate 35 potassium-bi'sulfate. Under this treatment of an alkali-metal and subjectingthe bath‘ solid potassium-persulfate is’ thrown down to electrolysis. . 100 in the bath while ammonium-bisul-fate goes 3. The process of obtaining ‘a persulfate‘ . into solution. This “process may be carried of an alkali-metal, which consists in sub‘ .out with a yield of from 80% at the anode, 'jecting a bath containing ammonium sulfate 40 while the reduction does 'not- exceed more and a. sulfate of-said alkali-metal to elec than 1. to 2%. A surprising discovery madev trolysis, and adding fresh supplies of alkali 105 by these applicants in this connection is, metal sulfate as the conversion of the alkali that by the same treatment sodium-persul-_ metal sulfate into the persulfate proceeds, fate, a body which has been'very difficult to reconvert persulfate of ammonium into ..45 to obtain heretofore,‘ being very readily the sulfate. ' , > . _ -_ soluble, can be ‘obtained with ease. Hither 4. The process of obtaining a 'persulfate 110 to this'salt could notteven be obtained with of an alkali-metal, which consists in sub the aid of carbonate of sodium fro-m am‘ jecting' 'a bath containing ammonium. sul monium-persulfate; it was necessary for this fate and, undissolved. alkali-metal sulfate to' .50 purpose to employ caustic. soda- or‘ sodium- electrolysis, and adding fresh supplies of hydrate, the escaping ammonia under this solid alkali-metal sulfate as the electrolysis treatment having been, absorbed with sul proceeds,‘ to reconvert persulfate .of' am -' '. furic-acid. The applicants havefound that monium into the sulfate. Q ' i by using ‘the same ~method as above de-' 5. The process of obtaining potassium: scribed, the ammonium-persulfate may be \persulfate, which consists in‘ causing a sul readily converted _into sodium persulfate, fate of. potassium, in an undissolved state 120 leaving as‘a by-product ammonium-‘sulfate, to react_on\_a' solutlon of ammoniumrper by treating the said ammonium-,persulfate sulfate. ' . with sodium-sulfate (neutral or bisulfate). '6. The process of obtaining potassium- . Here again, the conversion may be carried persulfate. ~which consists in subjecting a out concurrently with the electrolysis with bath containing a potassium-sulfate and am 125 particular advantage. However, in this monium-sulfate to electrolytic‘ action. case, -in viewl of the ready solubility of 7. The process of obtaining ‘ otassium- ' ‘sodium-persulfate, the two‘ electrodes ‘must persulfate, which consists in su jecting a 1,059,809 1 ' I ' a %

bat-h containing potassium-sulfate and am- ‘our signature s in the presence of two wit~ monium sulfate to electrolytic action, and nesses. ' - adding fresh supplies of potassium sulfate , GUSTAV ADOLPH. to the bath as the reaction proceeds to re- ALBERT PIETZSCH. 5 convert persulfa-te of ‘ammonium to the Witnesses: ‘ , sulfate. ’ ' A. VERE W. fCo'rTER, In testimony whereof we hereunto a?ix " MATHILDE K. HELD.