US1371698A - Process of and apparatus for electrolysis - Google Patents

Description

' O. LINDER.

PROCESS OF AND APPARATUS FOR ELECTROLYSIS.

Patented Mar. 15, 1921 3 SHEETSSHEEI 1- .3235).-.----...--..-----.Exx-

APPLICATION FILED JAN. 11, I918- Ewen or Oscar Lz'nder 0. LINDER.

PROCESS OF AND APPARATUS FOR ELECTROLYSIS.

APPLICATION FILED JAN-11,1918.

1,371,698. Patented Mar. 15, 1921.

3 SHEETSSHEEI 2.

0. LINDER. PROCESS OF AND APPARATUS FOR ELECTROLYSIS.

APPLICATION FILED JAN-11,1918- 1,371,698, Patented Mar. 15, 1921.

3 SHEETS-SHEE] 3.

J7me)? or 05cm Lmder 5 UNITED" stares OSCARLINDER, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECT PATENT OFFICE; 1

mo COMPANY,

,INC-ORPORATED, on NEW YORK. N. Y., A CORPORATION or NEW YORK.

To all (lll-OIIL itmu-y conccwt.

Beit known that I, OscAR LINDER, a citi zen of the Republic of Switzerland, residing at Chicago, in the county of Cook and State of Illinois, United States of America, have invented certain new and useful Improvements in Processes of and Apparatus for Electrolysis, of which the following is a full, clear, concise, and exact description.

This invention relates to an improved process of and apparatus for electrolysis, and more particularly to an improved process of and apparatus for completely eli'mmating salts and other ionized chemicals from their aqueous solutions by means of electrolysis.

Electrolysis of aqueous solutions is commonly carried on in practice for three main purposes. Its first and principal use is for the purpose of precipitating metals on the cathode, as, for example, in electro-plating and electrolytic refining of metals. A second use is for the purpose of obtaining certain chemicals, mostly elements, from their compounds by electrolysis, as for example, in the manufacture of chlorin, hydrogen, oxygen, etc. A third application, though of less importance, is the use of electrolysis in quantitative chemi 'al analysis It is well known in the art that electrolytic deposition, while frequentlyeficient in electrolyzing solutions containing ionized chemicals at a fairly high concentration, becomes less so with decreasing concentration for two principal reasons: fiist, because the ohmic resistance increases,. and second, because secondary reactions are apt to develop which lower the efiiciency of the process; for example, a common complaint is that the electrolyte turns acid.

In all practical applications of electrolysis for the above enumerated purposes, it is comparatively simple to avoid such compli cations, since there is a possibility of keeping the electrolyte always Well saturated with salts. so that the efficiency of the process remains high and the ohmic resistance of the electrolyte low. In electro-plating and electrolytic refining of metals this is generally accomplished automatically, because an equal or nearly equal amount of metal is dissolved from the anode as is precipitated at the cathode. Any deficiency is made. up by adding to the electrolyte a sufiicient quantity contaminated with conducting salts.

these cases the difliculties above explained, 70

PROCESS OF AND APPARATUS FOR ELECTROLYSISJ Specification of Letters JPatent. Patent d M 15 1921 I I v I p I Application filed January 11, 1918. Serial No, 211,382. I

ot a salt of the same or similar composition as the one contained therein. In the quantitative a mlysls, where all of a certain metal insolutlonls to be precipitated, it is customary to add to the electrolyte salts commonlv known as conducting salts. These salts aid where the salts are to be completely eliminated from waste liquors, or from Wash waters, or from solutions which'cannot be In due to decreasing concentration of the electrolyte, cannot be readily overcome, for economic reasons, in. the manner described, and it has, therefore, been impractical in the past to employ electrolysis in many such cases. There are many instances Where electrolysis might be applied for such purposes, but it has been found that its use is impractical, mainly on account of the secondary reactions which take place prominently when certain dilutions are reached Which render complete removal of all constituents practically impossible. Thus for example, the electrolyte may turn acid and the current will then preferably liberate hydrogen and oxygen at the electrodes in place of a metal and an acid radical, the removal of which is desired.

It is the object of this invention to overcome the above described difliculties, and

this has been accomplished by placing the anode in an electrolyte which is contained Within a porous container, and placing the porous container in the electrolyte into This conwhich the cathode is immersed. stitutes an arrangement similar to the one used in the Leclanch primary battery in which aporous cup servesthe same purpose, namely that of separating mechanically but not electrically the electrolyte surrounding and the products of the electrolytic action formed at the anode, from the electrolyte surrounding and the products of the electrolytic action formed at the cathode. In

place of a porous container any equivalent expedient, such as a porous diaphragm, may be used. I By using such an arrangement it is not cited, as for example, 65

only possible to completely separate the product separated out at the cathode from that separated out,at the anode, even if one or both products are soluble in the electrolyte, but it is also possible, by the use of two or more anodes to regulate the reactionthat is, the acidity or alkalinity, of the electrolyte surrounding the cathode. Another advantage of such an arrangement lies in the fact that the ohmic resistance of the whole cell can be kept comparatively low,

cell reasonably low. By means of this in-' vention the first condition is met by the use of a porous cup or diaphragm, which separates mechanically but not electrically the electrolyte surrounding the anode from that surrounding thecathode. The second condition is met by using two or more anodes, each one surrounded by its own electrolyte and separated from the electrolyte surrounding the others and from that surrounding the cathode by porous diaphragms, or by immersi ng all anodes in one electrolyte which is separated from the electrolyte surrounding the cathode by a porous diaphragm; also by using anodes of different materials, for example a soluble and an insoluble anod;- and by proper regulation of the current flow through each anode whereby conditions can be obtained at will which will tend to render the electrolyte surrounding the cathode neutral, acid or alkaline. The third condition can be met by surrounding the anode or anodes with an electrolyte of low ohmic resistance and by proper proportioning of the cell.

The improved process of this invention may be best explained by referring to the accompanying diagrammatic drawings. in

"which Fi ure 1 is a sectional front elevation ot.

an e ectrolytic cell in its simplest form.

equipped with a porouscup;

two porous cups;

Fig. 3 illustrates a sectional elevation ot'f an electrolytic cell equipped with a porous partition for separating the electrolytes;

Fig. 4 is a plan View thereof;

Fig, 5 illustrates a sectional elevation of;

an electrolytic cell equipped with two poarness L spectively in the desired electrolyte.

rous partitions for separating two anodes and their associated electrolytes from the cathode and its electrolyte;

Fig. 6 is a plan view thereof;

Fig. 7 is a sectional elevation in diagrammatic form rof the cell illustarted in Fig... 1 together with the required electrolyte circulating apparatus;.

Fig. 8 is a similar view oi the cell illustrated in Fig. 3, together with its electrolyte circulating apparatus;

Figs. 9, 11, 12, and 13 are sectional elevations of electrolytic cells equipped each with a porous partition for separating the anodes and their associated electrolytes from the cathodes and their electrolytes. embodying difierent constructions of the electrodes;

Fig. 10 is a plan view of the cell illustrated in Fig. 9, and

Fig. 14 is a sectional elevation of a cell equipped with a porous cup, showing the use of a metal lining of the receptacle as a cathode.

Fig. 1 of the above illustrations shows an electrolytic cell 10 in which is contained the electrolyte 11 which is to be subjected to electrolysis. Suspended in any suitable manner in this electrolyte is the cathode 19.. A porous cup 13 containing the anode 14 and its electrolyte 15 is positioned in the cell 10. The cathode 12 and anode 14 are'connected to any suitable source of electrical energy, as indicated in this figure.

Fig. 2 shows a similar electrolytic cell 16 containing an electrolyte 17 in which is suspended the cathode 18. This cell carries the two porouscups 21 and 22, in each of which is positioned anodes 23 and 241%- he anode and cathode are connected to some suitable source of electrical energy and preferably but not necessarily through a rheostat such as 25. I

The porous cups 13, 21, and 22 indicated in these two figures are preferably cylindri-' cal in form and are surrounded by the electrolyte contained in the cells 10 and 16'.

' similar to that shown in Figs. 3 and 4. the

cell 35 in this case being fitted with two 1 partitions 36 and 37, dividing it into the Fig. 2 is an electrolytic cell provided with chambers 38, 39, and 40, two anodes 41 and 42 being positioned in the chambers 38 and 40 and a cathode 43 in the chamber 39; Ohviously a cell such. as $35 could readily be. constructed with any desired number of partitions, thereby providing chambers separated from each other by a porous diaphragm, and thereby providing a cell in rated from one another.

which any desired number of different kinds of electrolyte may be utilized and 1n which these electrolytes will be maintained sepa- The anodes and cathode of this cell are likewise connected to any suitable source of electrical energy, if desired through an electrical rheostat such as 44.

Fig. 7 indicates an electrolytic cell which is similar in construction to that illustrated in Fig. 1 connected to the desired electrolyte circulating systenr. Thus the cell there shown is fitted with a porous cup 51 tontaining the anode 52 and its associated electrolyte. The electrolyte 53 which is to be subjected to electrolysis contained in the cell 50 has suspended therein the cathode 54. The .anode 52 and cathode 54 are connected to any suitable source of electrical energy. The electrolyte 53 is fed from the cell 50' by means of any suitable liquid conveying means sncha an overflow 55 into a settling tank 56. From the settling tank the electrolyte is discharged through the liquid conveying means 57 to a storage or wash tank 58. The;fiow of the liquid 53 from the cell 50 to the settling tank 56 and from said tank to the storage tank 58 is gravitationall produced. Connected to the storage tan: 58 is the pipe 59 which is connected to any suitable pump 60 diagrammatically indicated in the figure, the other side of the pump being connected with the pipe 61 which feeds the electrolyteinto the cell 50.

It will be evident, therefore, that with an apparatus such as shown in Fig. 7 the electrolyte 53 will be continually circulated, due to gravity and the action of thepu mp 60, from the cell 50 through the settling tank 56 and the storage or wash tank 58. In this circulation the electrolyte is subjected-to the electrolytic action of electrolysis through the cell 50, from which action it is absolutely independent in the settlin tank 56 or the storage or wash tank 58. he settling tank 56 is not always necessary, but if required will act to clarify the solution from any sediment or impurities collected therein during the process of the complete operation. The tank 58 likewise is not always required and serves as a means for storing theelectrolyte, or as an actual wash tank in which the electrolyte 53 may be utilized to perform any washing or other operations desired.

Fig. 8 illustrates a cell of the typeshown in Fig. QJtogether with an electrolyte circulating system. In this figure the electrolytic cell 64 is fitted with a partition 65 which divides this cell vinto the compartments 66 and 67. The compartment 66 con tains the anode 68 and its associated electrolyte, and the compartment 67 the cathode 69 and the electrolyte 7 0 which is to be subjected to the action of electrolysis. The

electrolyte 70 .is circulated from the cell 64 by means of the pipe/Z1 to the filter press 72,

and from there by means of the pipe 7 3 to,

the stora e or-wash tank 74. Obviously any type of titer press or settling means may be utilized for the press 72 and the tank 56 illustrated in Figs. 8 and 7 respectively. The electrolyte 70 is circulated from the washtank 74 by means of the pump 75 through the pipe-connection 76 which interconnects the pump 75 with the tank 74, and the pipe connection 77 which interconnects the pump with the cell 64. In addition to circulating the electrolyte 70 it may also be found convenient and usefulto circulate the electrolyte in which theanode 68 is suspended. When this is desired a storage tank such as 80 containingthis electrolyte 81 is connected by means of the piping 82 and the interposed pump 83 with the compartment 66 of the cell 64. The compartment 66 is also directly connected by means of the pipe 84 with the storage tank 80.

In'a system such as shown in Fig. 8, therefore, the electrolyte 70 which is to be subjected to electrolysis-Will be circulated from the cell 64 through the filter press 72 and the wash or storage tank 74 by gravity and will be pumped from the wash tank by means of the pump 75 back to the cell 64. Likewise the electrolyte 81 will be gravitationally fed from the compartment .66 of the cell 64 to the storage tank 80 and from said tank will be pumpedback to said compartment by means of the pump 83. It will be evident, therefore, that in a system of the type illustrated iii Fig. 8, the electrolyte 70 associated with the cathode as well as the electrolyte 81 associated with the anode will be continuously circulated.

Figs. 9 and 10 illustrate an electrolytic cell similar to the one shown in Figs. 5 and 6, with the exception that tlie two anodes 90,and 91, made of dissimilar materials, are placed in one anode compartment 92. The cathode compartment 93 of the cell contains the cathode 94; anodes and 91 are either indirect connection with an external source of electrical energy, as indicated in Fig. 9, or, as shown in Fig. 10, they may be connected through a rheostat such as 95. In the first instance, the amount of current flowing through the anodes is preferably controlled by the shape, dimensions, and depth of immersion of both anodes. In the other case, current The two regulatidn may be controlled partly in this manner, partlyby means of the rheostat, or

entirely by the rheostat.

the anode 96 being placed on the'bottom of the anode compartment 98 and the cathode l i I on the bottom of the cathode compartment 99.

Fig. 12 shows another modification and illustrates a cell equipped with a-horizontal anode 100 which is covered with a loose metal 101 in powder, sponge, or granular form. "The cathode 102 in this instance comprises the lining of the container 103. The container is divided into the anode compartment 104-. and the cathode compartment 105 by the porous partition 106. In this construction of an electrolytic cell the loose metal placed on the anode may be the same or of a'difierent character than that from which the anode itself is made. When the anode itself and the loose metal are composed of the same material the loose metal will go into solution in the electrolyte in the anode compartment 104, and thereby reduce 2 or prevent the deterioration or dissolution of the solid anode, and will therefore serve the purpose of utilizing an anode composed of a loose material in powder, sponge, moss, or granular form instead of a. solid material. When the loose metal and anode itself are composed of diiferent materials the arrangeinent would be the equivalent of two I solid anodes of dissimilar materials.

Fig. 13 indicates a modification of the electrolytic cell shown in Fig. 12, in that a solid anode material 110 is placed on a horizontal anode 111, the two being placed at the bottom on an anode compartment 112 separated from the cathode compartment 113 by' a porous partition 1141.

Fig. 14 illustrates another modification of an electrolytic cell in which the container 115 is fitted with a metallic lining 116 which servesas the cathode of the cell. Immersed 40 .in the cathode electrolyte 117 is a porous cup 118 which carries the anode 119v and the anode electrolyte 120.

Obviously any desired combination may be made of the cells illustrated in Figs. 1 to 6 and 9 to'l l inclusive or the various elements of the circulating systems illustrated in Figs. 7 and 8jinclusive. Thus a cell having any desired number of electrolytic comartments may be used, and the-electrolyte in any one or all of said compartments may be circulated, said circulating system including any of the well known types of apfi paratuses used for the purpose of fluid filtration clarification, etc., and also containing any suitable or desired type of fluid storing means and any convenient circulating means. Also the electrodes may be of any desired construction and may be placed in any desired position in the cell.

In the preferred application of this invention the solution to be electrolyzed is generally passed through a settling tank, as illustrated in Fig. 7, in which any sediment is allowed to settle out or through a filter, diagrammatically illustrated in Fig. 8, in which such sediment is filtered out. These opera tions are desirable in cases where the metallic deposit at the cathode is in very spongy form, in which condition it does not adhere well to the cathode and consequently is partly carried along by the"circulating electrolyte, and in cases where partial precipitation of the salts in the electrolyte 1n basic form takes place.

In most instances of the practical app'li- 75. cation of this invention there is an accumu; lation of some of the products of the electrolysis in the porous cup or compartment surrounding the anode. If this accumulation becomes excessive there is likely to be considerable diffusion of these products into the cathode compartment; and in order to avoid this, the electrolyte such as 81 surrounding the anode 68, illustrated in Fig. 8, should be circulated either intermittently or 85 continuously, depending upon the action desired, by some means, preferably by the pump 83, such as illustrated in Fig. 8. Instead of actually circulating the electrolyte 81 it is in some cases preferred to keep it at a uniform concentration by continuously or intermittently feeding in a small amount of water by any ordinary means, and allowing the electrolyte to overflow through the pipe 84 into the storage tank 80. The electrolyte 81 is generally of value since part of the original cathode electrolyte and the anode material may be recovered from it.

The invention herein described permits of so many variations and is applicable to so many conditions that it is not feasible to point out all the applications of the invention herein. The invention is obviously not limited to the examples and to the condiv tions cited, but can be employed in all cases where complete or substantially complete removal of salts or chemicals is desired from aqueous solutions, as set forth in the appended claims. These solutions may contain one or more salts and in many cases separation of these salts can be effected by the utilization ofthis invention.

As a specific example of the application of the process, reference will be made to the 0 eration of freeing the wash water used in washing vulcanized fiber from zinc chlorid. If electrolysis is attempted without the arrangement hereinbefore described, hydrogen and zinc will be deposited at the cathode and chlorin and oxygen at the anode and the electrolyte will become strongly acid, so that it works at a very low efficiency and complete removal of the zinc chlorid becomes impractical. In this case, it is preferable tobubject the wash water to electrolysis, 125.

using a zinc cathode and a. zinc anode the latter to be surrounded by a zinc chlorid solution inclosed in a orous cup or separated from the cathode e ectrolyte, by a porous diaphragm, as hereinbefore described. With this arrangement the zinc is precipitated at the cathode and the chlorm liberated at the anode in substantially equivalent propor prevented, even at the lowest conwntrations,

and the electrolyte is prevented from becoming acid and becomes. on the contrary, alkaline. If a carbon anode is used in place of the zinc anode there will be some liberation of chlorin and oxygen at the anode and some formation of hydrochloric acid in the electrolyte surrounding the cathode. By

using both a zinc and carbon anode, either in the same electrolyte or each in a separate porous cup or partition, as illustrated in Figs. 2 and 5. conditions will obtain whereby the electrolyte surrounding the cathode may be maintained acid, alkaline, or neutral. at will." This will be evident from the fact that the portion of the current which flows from the carbon anode to the zinc cathode has a tendency to form hydrochloric acid in the electrolyte surrounding the cathode, and

that portion which flows from the zinc anode to the zinc cathode has a tendency to render it somewhat alkaline, and thereforethe current flow in these circuits may be regulated by a rheostatic control or by the size of the electrodes or the depth of their immersion. so that these two actions will either neutralize one another and thus keep the solution neutral, or whereby either one action'or the other will predominate and make the solution either acid or alkaline.

In some cases partial elimination of the ingredients in the solution by precipitation is preferable and may be accomplished by so choosing conditions as to cause the electrolyte surrounding the cathode to become alkaline. For example, in the hereinbefore referred to PICT'GSS of removing zinc chlorid from the wash water in the manufacture of hard fiber this is easily accomplished by employing a zinc anode immersed ina. solution of zinc chlorid, which is separated from the solution to be electrolyzed by a porous diaphragm. In this case the reaction is so controlled that part of the zinc in the solution is precipitated out as zinc hydroxid,

which is allowed to settle out in a settling tank. such as illustrated in Fig. 7, or filtered out in a filter press such as illustrated in Fig. 8.

'For the purpose of separating the electrolytes, any kind of cup, diaphragm, or partition made of any desired material may be utilized. Thus, a mineral diaphragm such as clay or unglazed porcelain, an animal diaphragm such as skin, leather, hardened gelatin, coagulated albumin, or pigs bladder; or vegetable diaphragms such as,

fiber, parchmentized paper, viscose, etc.

The cathode may be of any desired metal,

or of carbon or shape.

Instead of using two anodes immersed in the same compartment, it is possible to use a single anode, allow it to become partly or wholly coated or covered with another metal or surround it with another metal in graphite and in any'desired loose form, and thus have the same effect as having two separate anodes in the same electrolyte. Obviously, in this manner the flow of electric current 'may be regulated to a certain degree by covering the one anode material more or less with the other anode material. In this manner a certain amount of regulation of the flow of current through each part of the anode is also possible.

Where two or more anodes are employed and each one is immersed in a separate electrolyte, separated from the others by a porous diaphragm, these anodes may be. either of the same or of difierent materials. The use of two or more anodes of the same material is sometimes preferred, and variations are'introduced into the electrolysis by choosing the proper electrolyte, current and current density for each anode.

The choice of the electrolyte in which the anode orcanodes are immersed must be determined for each separate case. As a general. rule, a salt will bechosen which is identical to that which is to be removed from the solution into which the cathode is immersed. This is not, however, necessary and a great many variations may be introduced by choosing electrolytes of different compositions and concentrations.

Obviously the invention is not limited to the preferred embodiment thereof herein shown. other forms and applications thereof being contemplated, as set forth in the following claims.

What is claimed is: 1. The method of eliminating a salt or lution, which consists in electrolyzing the solution between a cathode and a plurality of anodes of dissimilar materials, each anode being immersed in its own electrolyte each of said electrolytes being separated from each other and from said solution by a porous diaphragm.

2. The method of eliminating a salt or other ionized chemical from its aqueous solution, which consists in electrolyzing the solution between a cathode and a plurality of anodes of dissimilar materials, all anodes being immersed in an electrolyte which is separated from said solution by a porous diaphragm. 5

3. The method of regulating and controlling the reaction of a solution containing ionized chemicals, which consists in subjecting the solution to electrolysis between a cathode and a plurality of anodes of dissimilar materials, each one of-said anodes being immersed in an electrolyte which differs from said solution in composition or concentration, and in separating sald electrolytes from each other and from said so.- lution 13y porous diap-hragms.

4:. The method of regulating and control ling the reaction of asolutlon containing ionized chemicals, which consists in subjecting the solution to electrolysis betweena cathode and a plurality of anodes, said anodes of dissimilar materials being immersed in an electrolyte which is separated from said solution by a porous diaphragm.

5. The method of separating a water soluble salt or other ionize chemical from other salts or chemicals by subjecting an aqueous solution of the mixtureof these chemicals to theaction of electrolysis betweenacath-Y ode and a luralit of anodes of dissimilar materials, t e a-no es being immersed in an electrolyte which is separated from said solution by a porous diaphragm.

6. An electrolytic apparatus for the removal or deposition of salts or their equivalents from their aqueous solutions, comprising in combination, a cathode, a solution from which the salts are to be removed in which said-cathode is immersed, a plurality of anodes of dissimilar materials, an elec-. trolyte for each of said anodes, and porous diaphragms separating said electrolytes from each other and from said-solution.

7. An electrolytic apparatus for the removal or deposition of salts or their equivalents from their aqueoussolutions, comprismemes ing in combination, a cathode, a solution from which the salts are to be removed m whiclrsaid cathode is immersed, a plurality of anodes of dissimilar materials, a common electrolyte for said anodes, and a porous diaphragm separating said electrolyte from said solution.

8. An electrolytic apparatus for the removal or depositlon of salts or their equivalents from their aqueous solutions, com rismg in combinatlonyan electrolytic ce 1, a plurality of anodes of dissimilar materials,

a cathode, a solution from which the salts are to be removed in which said cathode is.

immersed, an electrolyte for each of said anodes, and means for separating saidelectrolytes from each other and from said solution whereby diffusion between said electrolytes and said solution is prevented.

9. An electrolyticwapparatus for the removal or deposition of salts or their eqirivalents from their aqueous solutions, comprising in combination, an electrolytic cell, a

cathodefa solution from which the salts are

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