|Publication number||US2643223 A|
|Publication date||Jun 23, 1953|
|Filing date||Feb 7, 1951|
|Priority date||Feb 10, 1948|
|Publication number||US 2643223 A, US 2643223A, US-A-2643223, US2643223 A, US2643223A|
|Inventors||Notvest Robert W|
|Original Assignee||American Brake Shoe Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Non-Patent Citations (1), Referenced by (7), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
June 23, 1953 R. w. NOTVEST APPARATUS FOR ELECTROLYTIC ANALYSIS Original Filed Feb. 10, 1948 Patented June 23, 9
UNITED STATES APPARATUS FOR ELECTROLYTIC ANALYSIS Robert W. N otvest, Affton, Mo., assig-nor to Amere ican Brake Shoe Company, New York, N. Y,, a corporation of Delaware V Original application February 10, 1948, Serial No.
PATENT OFFICE 7,366. Divided and this application February 7, 1951, Serial No. 209,841
adhere firmly to the anode whereas, on the other hand, reducing gases such as H2 and NH3 tend, of course, to migrate to but do not tend to ad here firmly to the cathode. However, the adher- This invention relates to an apparatus for the 5 ence of such oxidizing gases as N02 and 02 upon electrolytic quantitative analysis or determ-inathe anode tends to build up the internal resistance tion of copper and lead in copper-bearing and of the electrolyte, thereby causing excessive overlead-bearing metals or alloys. voltage with resulting formation of spongy and In the quantitative analytical determination irregula and loosely adhering deposits of metalor analysis of copper and lead in copper-bearing he copper and F002 upon the cathode and anode, and lead-bearing metals or alloys, or other specirespectively. mens, in acid solutions, these metals are electro- The foregoing and other problems which are lytically deposited as metallic copper and as lead involved in the quantitative electrolytic determioxide (P1002) upon a platinum wire gauze cathnation of copper and lead have been recognized ode and anode, respectively, of known weight. In heretofore in the art and attempts have been the case of copper, the copper content of the made in various ways to overcome these difficulmetal or other specimen under analysis is then ties. Thus, for example, mechanical electrolyte determined by calculating the difference in the stirring devices, rotating electrodes, and other weight of the platinum cathode before and after mechanical devices have been employed and air the copper is deposited thereon. Similarly, in the stirring of the anode by the introduction of air case of lead, the lead content of a metal or other into the electrolyte have all been employed. l-Iowspecimen under analysis is calculated by deterever, none of these prior mechanical devices or mining the weight of the lead oxide deposited methods has, insofarasI-am aware, been entirely upon the platinum anode and then calculating successful, for a number of reasons. Thus one the weight of the lead in the deposited lead oxof the serious difficulties involved in the use of ide in accordance with the percentage composimechanical electrolyte stirring devices is the fact tion of the lead oxide. that such mechanical electrolyte stirring devices However, a number of problems have been ex..- tend to dislodge the deposits of pp d 0? perienced heretofore in the electroanalysis of from the cathode and anodaresp iv ly,Wh copper and lead in acid solutions and these probas agitation or scouring 0f he anode with air. lems have not heretofore, insofar .as I am aware, While tending o dislodge the firmly adh r h en successfully s l d, idizing gases such as N02 and 02 from the anode,
One of the difficulties which has been expers no chemical efiect n preserving he p o ienced in the electrolytic quantitative determinat lyte w thi d s red limits or in pr tion of copper and lead has been the fact that Venting imbalance d resulting O f q Q the oxygen which accumulates upon the anode the electrolyte wi h n equent formation of during the electrolysis tends to adhere firmly to p ngy and irregular-shaped and loosely adherthe anode and to oxidize any nitric acid present i s deposits of cop and P1 2 p he oath: in the electrolyte to ammonia and N02 and these Ode and de c i yreover. the use gases migrate to and tend to accumulate upon O rotating "5 fi i onl tends o dislodge the cathode and anode, respective1y,-where they the deposit accumulated thereon but renders it retard deposition, cause spongy deposits of copdifiicult to maintain the characteristics of the per and PbOz, and otherwise generally cause incurrent and of the electrolyte employed constant accurate quantitative results, unless eliminated. during the electrolysis.
Another difficulty which has been experienced Accordingly, an object of the present invention in the use of prior methods and apparatus for is to provide a new and improved apparatus for i the quantitative electrolytic determination of the quantitative electrolytic determination of copper and lead is the fact that oxidizing gases, copper andlead in copper-bearing andlead-bearsuch as N02 and 02, formed in the electrolyte I ing metals and ores and which, in use, overcome during the electrolysis, tend. to migrate to andto he f oi g and Other difliculties Xp amazes 3 in the use of prior methods and apparatus for the quantitative electrolytic determination of copper and lead.
An additional object of the present invention is to provide a new and improved apparatus for the quantitative electrolytic determination of copper and lead and in the use of which more exact and more rapid quantitative electrolytic determinations of these metals can be made than has been possible heretofore in the use of prior method and apparatus.
A further object of the invention is to provide a new and improved apparatus for the quantitative electrolytic determination of copper and lead and in the use of which deposition-retarding and oxidizing gases, such as N02 and 02, which tend to gather upon and to adhere to the anode, and to cause spongy and loosely held deposits thereon, are continuously and thoroughly removed from the anode during the electrolysis without dislodging therefrom the PbO2 deposited thereon.
Still another object of the invention is to provide a new and improved apparatus for the quantitative electrolytic determination of copper and in the use of which the internal resistance of the electrolyte is minimized.
Another object of the present invention is to provide a new and improved apparatus for efiecting the relatively rapid and yet highly accurate quantitative determinations.
In the drawing:
Fig. 1 is a side elevational View, partly in section. illustrating a preferred form of electrolysis apparatus embodying the present invention;
Fig. 2 is a vertical sectional view illustrating the construction of the anode and related parts of the electrolysis apparatus shown in Fig. 1;
Fig. 3 is a bottom plan view, looking in the direction of the arrows 33 in Fig. 2, illustrating the construction of the new anode apparatus shown in Fig. 2;
Fig. 4 is a top plan View, looking in the direction of the arrows l-4 in Fig. 2, of the new anode apparatus shown in Fig. 2; and
Fig. 5 is a partial sectional plan view on line 5-5 in Fig. 1.
A preferred form of the new electrolytic apparatus is illustrated in the drawing, wherein it is generally indicated at I0, and comprises an anode unit, which is generally indicated at II, and a cathode unit which is generally indicated at 2, both of which are shown as being arranged in an electrolytic beaker I3. The anode unit I I includes a tubular metal combination current-conducting and gas-conducting member I4 to which a lead-in conductor I5 may be attached for connection to a suitable current source. The anode unit I I also includes a preferably sandblasted and substantially cylindrical platinum wire gauze electrode it of suitable mesh. The combination current-conducting and gas-conducting tubular member It extends through a central opening I8 which is provided in a spider member I1 which is attached in any suitable manner, as by a friction fit, upon the open upper end portion of the platinum wire gauze anode electrode I6 (Figs. 2 and 4). The lower end portion I9 of the combination currentconducting and gas-conducting tubular member I4 extends downwardly below the open lower end of the platinum wire gauze anode electrode l6 where the said lower end portion I9 of the said tubular member I4 is secured, in any suitable manner, as by welding, in a central opening 29 which is formed in a substantially circular closure member or cap 2| having an upper flanged portion 22 which is attached in any suitable manner, as by welding, to the outer surface of the lower end portion of the substantially cylindrical platinum wire gauze anode electrode I6 (Figs. 2 and 3). As shown in Figs. 2 and 3, the lower end portion I9 of the tubular member I4 has an open lower end 24 which opens onto and below the lower surface 25 of the closure member or cap 2| and which is curved convexly downwardly, as best shown in Fig. 2.
The anode unit II is completed by a flexible rubber tubular member 28 which is attached to the open upper end portion of the combination current-conducting and gas-conducting tubular member I4 so that the said tubular member I4-28 may be connected to a suitable source of carbon dioxide under pressure of from 1 to 15 pounds per square inch.
A procedure-that'is preferably followed in connection with the practice of the present invention for dissolving the copper-containing and lead-containing metal to be analyzed is disclosed in my aforesaid patent, the disclosure of which patent is herein incorporated by reference with respect to the preferred analytical methods to be followed when using the apparatus of the present invention.
After the solution containing the metals to be analyzed is prepared as aforesaid, the solution thus prepared is then transferred to the beaker I3 (Fig. 1) and the anode unit I I and the cathode unit I2 are immersed therein whereupon the control valve (not shown) for the CO2 supply to the combination current-conducting and gas-conducting member I428 is adjusted to produce a steady flow of CO2 at a selected pressure of from 1 to 5 pounds per square inch through the tubular member I428, whereupon the current from the lead-in conductors I5 and 2'! to the anode and cathode units II and I2, respectively, is turned on. The electrolysis thereupon proceeds in the electrolysis beaker I3, the copper content of the electrolyte being deposited as metallic copper upon the substantially cylindrical platinum gauze cathode 29 and. the lead content of the electrolyte being deposited as PbOz upon the substantially cylindrical platinum gauze anode IS.
The current to the lead-in conductors I5 and. 21 and the flow of CO2 through the tubular meinber I4.26 may then be shut off and the anode and cathode units I I and I2 respectively, removed from the beaker I3, and the weight of the metallic deposits thereon is determined and the amounts of copper and lead in the sample res-pee tively calculated.
It has been found in the practice of the present invention that as the CO2 flows downwardly through the combination tubular current-com ducting and gas-conducting anode member I it emerges in the form of a steady stream of CO2 bubbles from the open lower end 2 2 of the tubular member I 4 whence the CO2 bubbles pass upwardly over the convexly downwardly curved bottom surface 25 of the closure member or cap 2i which is attached to the lower end portion of the substantially cylindrical platinum gauze anode member I6.
Moreover, it has also been found in the practice of the present invention that as the CO2 bubbles emerge from the open lower end portion 24 of the tubular member I4 and travel upwardly in the electrolyte over the convexly downwardly curved lower surface 25 of the member 2! the said convexly downwardly curved lower surface 25 of the member 2! imparts a whirling motion to the C0 bubbles and as the stream of whirling CO2 bubbles pass upwardly in the electrolyte over the external surface of the substantially cylindrical platinum auze anode it and the said CO2 bubbles create a turbulence and exert a scouring action upon the said platinum gauze anode l6, and upon the deposit of PbOz thereon and which results are not obtained when the bottom of the closure member 211 is formed as a square or other substantially flat surface. In this manner substantially all of the deposition-retarding and oxidizing gases, including O2 and N02, which accumulate upon the platinum gauze anode l6 and upon the PbOz deposit thereon (and which deposition-retarding and oxidizing gases would otherwise cause spongy and loosely held deposits of PbO2 as well as building up the internal resistance of the electrolytic cell), are removed from the platinum gauze anode it and the PbOz deposit thereon in status nascendi. In this manner good uniform and firmly held deposits of P1002 on the anode 16 are assured, the internal resistance of the electrolytic cell is minimized and overvoltage in the electrolytic cell is eliminated, oxidation and resulting staining of the copper deposited on the cathode 29 are prevented and good firm deposits of salmon-colored copper on the cathode 29 are obtained, the tendency of the ferric nitrate content in the elecrolyte to increase with resultant corresponding increase in the solvent action of the ferric nitrate upon the copper deposited on the cathode 29 is counteracted and reduced, and more accurate quantitative electrolytic determination of both lead and copper are assured.
It has also been found in the practice of the present invention that the steadily flowing stream of CO2 bubbles thus passed into the electrolyte not only exerts a mechanical scouring or cleaning function upon the platinum anode l6 and upon the PbOz deposit thereon, so as to remove in status nasoendi the deposition-retarding and oxidizing gases, such as 02 and N02, which would otherwise adhere and cling to the cathode l6 and the PbO2 deposit thereon, but the steady flow of CO2 thus passed into the electrolyte during the electrolysis performs a second but not fully understood function which is believed to reside in the formation of carbonic acid (H2003) in the electrolyte and which tends to neutralize the NHz which is formed in the electrolyte, particularly in the latter stages of the electrolysis. Hence it is believed that the 002 thus functions to maintain a definite acidity in the electrolyte throughout the electrolysis and thus keeps the temperature of the electrolyte down, preserves a more uniform current flow through the electrolyte, and thus accelerates and promotes the deposition of the last traces of copper and lead in the clos trolytc upon the cathode and anode, respectively, with correspondingly more accurate quantitative electrolytic determinations of these metals than has been possible heretofore in the use of prior apparatus. That such a second function is performed by the CO2, in addition to its function of mechanically scouring the platinum anode l8 and the PbOz deposit thereon, is shown by the fact that if a stream of air is passed through the tubular anode member l l-28, in place of a stream of CO2, but under otherwise identical conditions, and with all other variables controlled, the resuits in terms of quantitative electrolytic determinations of copper and lead are significantly and consistently less accurate than when a stream of CO2 is directed along the sides of the anode, as in the practice of the present invention. That this is so may be seen by referenc to the comparative examples disclosed and contrasted one with the other in my aforesaid patent, which comparative examples relate to brasses described therein as being of known compositions.
It will thus be seen from the foregoing descrip tion, considered in conjunction with the accompanying drawing, that the present invention provides a new and improved apparatus for the rapid and accurate quantitative electrolytic determination of lead and copper in lead-bearing and copper-bearing metals, ores, and the like, and that the invention thus has the desirable advantages and characteristics, and accomplishes its intended objects, including those hereinbefore pointed out and others which are inherent in the invention. While the apparatus has been described hereinabove from the standpoint of an analysis of a copper-lead sample along the lines disclosed in my aforesaid Patent No. 2,544,802, it will be appreciated that the present apparatus may also be utilized in other types of electrolytic analyses wherein it may be determined that a scavenging action may be had at the anode by means of the apparatus of the present invention.
1. In an electrolytic apparatus for quantitative determination of solutions, an electrode unit comprising, a substantially cylindrical platinum gauze electrode adapted to be immersed in the solution, the bottom of the said gauze electrode being closed by a convexly rounded and imperforate closure member provided at its bottom center with a passage extending therethrough to open into the interior of said cylindrical electrode, and a hollow tubular current-conducting element extending longitudinally of and substantially centrally in the said gauze electrode, one end portion of the tubular element being adapted to be connected to a source of CO2 gas, the other end portion of the tubular element being sealably positioned in the said passage whereby C02 gas conducted through said tubular element will bubble upwardly along the outer sides of the closure member to clean adherent oxidizing gases from the outer sides of the gauze electrode during electrolysis.
2. An electrode unit adapted to be immersed in a solution of an electrolyte and adapted to cooperate electrically with another electrode for quantitatively determining the cation content of said electrolyte and comprising, a substantially cylindrical platinum gauze electrode, an imperforate closure member sealed to the bottom of said gauze electrode and being provided with a passage centrally located in the bottom thereof, the side walls of said closure member being convexly tapered upwardly from said passage toward the bottom edge of said gauze electrode, and a hollow tubular gas-conducting element extending longitudinally of and axially through the gauze electrode, the upper open end portion of the said tubular element being adapted to be connected to a source of CO2 gas, the lower end portion of the said tubular element being sealably positioned in the said passage in the said closure member whereby CO2 gas conducted downwardly through said tubular element will bubble upwardly along the outer sides of the closure member to scavenge the outer sides of the gauze electrode during electrolysis.
3. An electrode unit adapted to be used in conjunction with an electrolytic apparatus for the quantitative determination of solutions comprising, a substantially cylindrical and hollow electrode having at the lower end thereof a generally rounded and upwardly curved cup-shaped bottom portion which is imperforate except at the central point whereat a passage is formed therethrough to open into the interior of said electrode, the rim of said bottom portion coinciding substantially with the bottom edge of said cylindrical electrode, and an elongated gas-conducting tube connected to said passage at the inside of said cylindrical electrode, said tube being extended axially of and through said cylindrical electrode to be connected with a source of gas under pressure whereby said gas may be conducted to said passage in said bottom portion to exit therefrom and bubble upwardly along the sides of said bottom portion and said substantially coinciding rim and bottom edge to purge adherent gases and other foreign matter tending to accumulate on the outer sides of said cylindrical electrode during us thereof.
ROBERT W. NOTVEST.
References Cited in the file of this patent Transactions of The Electrochemical Society, V0176 (1939), pages 63-68,
Zeitschrift fur Elektrochemie, vol. 17 (1911), pages 905, 906.
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|U.S. Classification||204/402, 204/260, 204/400, 204/277, 204/284|