Nov. 19, 1946. 2,411,238 J. ZENDER PROCESS AND APPARATUS FOR DIALYZING SOLUTIONS Filed July 8, 1943 "'7 F2541 . \\/" \\ \\ \ \\ ZSheets-Sheet 1 Ill In INVENTOR. BY JUST! ZENDER - ‘ Patentecl- N... 1c, 1946 2,411,23 v " . STATES “PATENT time amass PROCESS AND‘APPARA'I‘US FOR DIALYIZING SOLUTIONS Justin Zender, Fredericksburg, Va.-, assignor to Sylvania Industrial Corporation, Fredericks burg, Va., a corporation of Virginia ' Application July 8, 1943, Serial No. 493,918 ' l 7 Claims. (Cl. 210-85) 2 The invention relates in general to dialysis, and, In the now preferred embodiment the apparatus in particular, to a process and apparatus for the separation of a soluble. substance from its solu comprises a. chamber having headers disposed transversely adjacent each end to divide the chamber into three separate compartments, tion by dialysis, and to correlated improvements designed to enhance the structure and function and to extend the uses of such apparatus. It has been Proposed to dialyze soluble mate _ tubular dialyzing membranes connected at each end to the headers and communicating with a common liquid compartment, and means for pass ing a ?uid around the tubes in the central com rials from their aqueous solutions through hydro philic membranes, such, for example, as sheets of regenerated cellulose, parchment paper, and the ‘ partment. ?rmly sealed to avoid loss of liquid during dialysis. -_In the following speci?cations and in the ap pended claims, the term “dialyzate” will be used to designate the solution being dialyzed in accord ance with recent usage in the art; the term “dif fusate” will designate the solution of the material which diffuses through the membrane during To clean the apparatus or to replace a broken sheet, it is generally necessary to completely dis- - dialysis, ‘and the term “dialysis” will be used to designate the diffusion of soluble substances ‘ like. However, dialyzers employing membranes in the form of ?at sheets have certain inherent disadvantages. For example, the edges of the .sheets must be maintained under pressure or mantle the dialyzer. Further, to decrease break through a semi-permeable membrane from one . age, the membranes must be supported over their liquid into another. ' ‘ surfaces. Finally, such prior apparatus did not '20 4 The invention accordingly comprises the provide any 'means for retarding the dilution of features of construction, combinations of ele the solution being dialyzed. Thus, sheet dialyzers ments, and arrangement of parts which will‘be of prior design have generally been complicated exempli?ed in the construction hereinafter set in construction, dif?cult to repair or- to clean and forth and the scope of the invention will be in capable of handling only small volumes of liquid. -25 dicated in the claims. Accordingly, it is a general object of the present For a more complete understanding of the; invention to provide a dialyzer which will be nature and objects of the invention, reference capable of handling large volumes of liquid and should be had to the accompanying drawings in which will operate rapidly. which It is a further general object to provide a 30 dialyzing apparatus which is easy to construct and to'clean and in which broken ‘membranes may be replaced without completely dismantling Fig. 1 represents a side elevation, partly in’ sec- - tion, of one embodiment of the apparatus of the invention; Fig. 2 represents a cross-sectional view of the dialysis chamber of the apparatus of Fig. 1 It is another object of the invention to provide .35 taken along the line 2-2 thereof; a process for the separation of water-soluble Fig. 3 is a side elevation, partly in section, of substances from their aqueous solutions in a rapid one of the dialyzing tubes used in a second em and ef?cient manner, and in particular for the bodiment of the apparatus; separation of products of fermentation from the Fig. 4 is a side elevation, partly. in section, of ‘ fermented liquor. _ 40 the dialyzer of the invention utilizing a, double A speci?c object is to provide an-apparatus tube; having means for retarding the dilution of the Fig. 5 is a top plan view, in section, of the-ap solution being dialyzed._ ‘ _ , paratus of Fig. 4 taken along the line 5—5 there.. Other objects of the invention will in part be of ; and _ . obvious and will in part appear hereinafter. Figure 6 is a top plan view in section of-the 45 the dialyzer. According to the present invention, there is provided an apparatus for the dialysis of solutions comprising, in combination, a chamber, a .mul tiplicity of tubular dialyzing membranes disposed apparatus .of Figure 4 taken along the line 6-6 ' thereof. In that embodiment of they apparatus shown in Figs. 1 and 2, the dialyzing chamber proper therein, means to pass the solution to be dialyzed 50 comprises a vertical outer chamber 10, which is into contact with one surface of the tube, means shown as a cylindrical chamber, but which may to pass another liquid into contact with the be of any cross-sectional shape. The chamber is other surface of the tube, and preferably means to continuously concentrate the solution. being dialyzed so as to increase the rate of dialysis. closed at the top by a removable plate II, and is closed’ at the bottom by a conical base [2, which 55 is provided with a drain I3 having a valve l4. ' 2,411,288 , Situated, adjacent the. ends inside the chamber "I8. ‘there are positioned headers I8 and 16, each -.4 ‘ the invention can be arranged without transcend ing the scope of the invention so as to provide provided with a plurality of holes. Short sections thatthe dialyzate and the di?'usate both ?ow up of pipe H are threaded into theupper header I5 ward or downward in the same direction instead and similar sections of pipe 22 are threaded into 5 of ?owing countercurrent to each other as shown in Fig.1. _ the lower header I6, These pipes serve to anchor the dialysis tubes I8 to the headers. C , Further, the apparatus of the type shown in The chamber-1H] is provided with a removable 1 may be so readily modi?ed by anyone side portion 38 which makes the interior accessi ‘skilled in the art, without transcending the‘ scope ble from the outside. When it is desired to 10 of the present invention so that the chamber I8 change or replace a tube, the apparatus is ‘ and the tubes I8 are ‘disposed’ in a horizontal plane. Inasmuch as the tubes I8 during oper ation are‘ not only completely ?lled with liquid drained, the bolts 39 removed, and the side por tion 38 of the chamber and the plate I I taken out. The‘ upper end of the tube is then pulled but- also are completely surrounded by liquid, through the section of pipe l'L/and the end turned 15 the tubes willrequire little or no horizontal sup; down over the upper end of the pipe H to form port. ‘If the tubes I8 are ?lled with .dialyzate, I the cuff 23. The band 24, which may be formed which has a higher speci?c‘gravity than the dif- . ‘ of rubber, as shown, or of metal or the like, is fusate, the ‘tubes will tend to ?oat so that they - then slipped over the cut? 23, anchoring it se can be kept in position merely by suitable guide curely to the pipe IT. A band‘24' similar to the, 20 pins. i ‘ ' band 24 is then slipped over the free lower end There is also shown in Figs. '3, 4, 5v and 6 an of the tube‘ I8, and the end of the tube inserted‘ , other embodiment of the apparatus of the invenover the upper end of the lower pipe 22'. The tion in which the dialyzing tubes are double or band 24' vis'then slipped down“ over the end of multiwalled.v Referring to Fig. 3, this-embodi _ ‘the tube I8, anchoring it securely to the pipe 22. 25 ment comprises. an inner dialyzing tube I811. The coupling shown in Fig. 1 has the advantage surrounded by a dialyzing tube I8b of vlarger di- > ‘of maintaining the maximum diameter of the tube I8 at the joint, and thus does not interfere ameter, and, if necessary, supported externally. > by means of a textile ‘tube I8c made of an open mesh fabric whether of woven, knitted, or braided with the flow of the liquid through the tube I8. ’ The dialysis tubes I8 may be disposed and 'ar- 30 construction. The surrounding outer dialyzing ranged within the chamber I0 in any desired tube IN: is particularly advantageous when-it is manner, in rows, for example, or in concentric desired to concentrate the dialyzate while it is circles as shown in Fig. 2. ' being subjected simultaneously to dialysis. Thus The space between > the tubes can be varied as desired, ‘but in general a distance of the order of 1/2 to 1 inch is sum- 35 cient. It is to be understood‘ that a space exists around all of the vtubes illustrated in Fig. 2, and that none of these tubes are in direct‘contact with each other along their longitudinal surfaces. It is to be understood that the apparatus shown 40 in Fig.‘ 1 may be constructed and arranged so that the dialyzate may be caused to pass inside ’ the tubes. or outside the tubes, but for the pur pose of illustration only, the apparatus of Fig, 1 is constructed and arranged so that the 'dialyzate 45 a plurality of the tubes‘ illustrated in Fig, 3 may be supported between the headers as shown' in the apparatus of Fig. 4,‘ leaving an air space'35 can be introduced into the lower section 25 of a ‘Illa requires the‘ use of double headers at'the. ‘top andbottom of the chamber. Accordingly. the between the tubes. The side walls of the cham ber 35.are solid as shown in the ?gure. However,. there are no front and back walls to the cham ber 35, as‘ is fully brought out in Figure 5. Thus ‘ it is possible to blow air through the chamber 35 across the outer surface of the tube I8c, thus causing an evaporation of liquid through the wall of the tube I8b, as shown in Figure 5. Positioning ‘the double tubes in the chamber the chamber I8 by means of the pipe 28, the di alyzate ?lling the lower section of the pipe up outer tubes I 8b and I80 are a?lxed to the inner ward through the interior of the tubes I8-and headers I5a and Ilia, while the inner tube I8a 7' ?lling the upper section 21 until ‘it over?ows‘ 50' is a?ixed to the lowermost header I5 and the ‘through the outlet 28. The di?usate will be 111-. troducedinto the intermediate chamber 29 at a the top through the pipe 38 and will be removed ' ‘ uppermost header It. In this embodiment, it'is preferable to have the dialyzate occupy the space , between the tubes 18a and I'8b, and to have the at the bottom through the pipe 3|. It is to be \ diifusate occupy the space in the interior of the understood that the circulation of the dialyzate 55 tube I8a. Accordingly. referring to Fig. '4, the and/or of the diffusate may be continuous or dialyzate is introduced into the lower section 25a intermittent. ‘When it is desired to clean the through the inlet ‘tube 26a so that it ?lls the‘ ' apparatus, the dialyzate may be drained off lower section and rises through the space be through the exhaust ‘pipe I3 which is positioned tween the tubes I So and I8!) and ?lls the upper at the lowermost point of the bottom section 25. 60 section 21a and ?ows out through the exit tube It should be noted that the present apparatus 28a. The diifusate can be introduced at the top is so constructed that the dialylzing tubes I8 are of the chamber into the section 86 through the completely submerged in liquid so that no por~ pipe 30a, whereupon it ?lls this section and ?ows - ' tion isin contact withthe air. This is a desir down through the interior of the tube I 8a and able feature since it has been found that cer- 85' ?lls the lower section 81 from which it passes tain- membranes, particularly those formed of throughythe exit tube 3| a. non-?brous cellulosic materials, are attacked by i ' Since the front and back walls of the chamber certain bacteria or organisms found in fermented , v35 are open, ltlis a simple matter to a?ix the“ sugar solutions and molasses ‘resulting in the tubes I81) and rI8c to'the header IIa. In order/ rapid deterioration -,of .the‘membrane.» This ac- 70 to provide access to the inner ‘tubes I841 in the tion is avoided or substantially retarded when chamber 25a-and to the upper parts of the outer the'm'embranes are completely submerged in the tubes I8b_ and I8c in the chamber 2'Ia'and the liquid, and precautions are taken to avoid in upper part of the innertubes I8a, and. the chem; ' troducing bubbles of air in either of ,the liquids. ber 36, removable front portions are provided in ' It'is also to be understood that the apparatus of 75, the walls of the chambers.‘ A typical construc 5 2,411,238 ' tion oi’vthe walls of each of these chambers is the wet gel state, i, e., while they are swollen shown in Figure 6 which represents ‘a cross—sec with water. tional view of the chamber 25a taken along the line 6-6 of Figure 4. The removable front wall portion 45 is ailixed to the apparatus wall‘ Illa by means of the bolts 41. Similar removable wall portions are provided in chambe'rs'Z‘la and 36. ,_ . On the other hand, when it is desired to sepa- , rate a hydrophilic organic liquid from water or organic compounds of a di?erent type there may _ be employed tubes formed of hydrophobic col loidal materials as a class of which there may During the operation 'of’the apparatus shown be given by way of example, tubes formed of synthetic resins such as polyvinyl resins, methyl in Figs. 4 and 5, the soluble substances are caused to di?use from the layer of dialyzate which passes in the space between the tubes l_8a and “lb into the diifusate which is ?owing through the in- '1 terior of the tube ma. Simultaneously, water or methacrylate resins, chloroprene, nylon, chlorin ated rubber and the like, or from an organic sol solvent from the diffusate will be ?owing through the tube l8a into the dialyzate thus diluting the 15 dialyzate. If the procedure of dilution is not re- ' tarded, it will result in the slowing down of the process of dialysis,vthe rate of which depends ent-soluble cellulose derivative such, for exam ple, as a cellulose ester, cellulose ether, mixed cellulose ester, mixed cellulose ether, a mixed ether ester of cellulose, as well as tubes formed of two or more resinsor two or more cellulose derivatives, also tubes formed from a mixture of a hydrophobic‘resin with a hydrophobic cellu- upon the difference in concentration of the sol lose derivative. When hydrophobic tubes are em uble' material between the dialyzate and the dif 20 ployed they are preferably used in the swollen fusate. Thus, according to one embodiment of gel state, i. e., while they are saturated with the the present invention, air is blown over the out organic liquid which it is desired toevaporate side of the multiwalled tube so that water is through the tube. continuously evaporated from the diffusate . , _ The present apparatus is adapted forv dialyz through the wall lab and through the open mesh fabric iBc. It has been found, for example, that 25 ing both organic and inorganic substances from organic or aqueous solutions. On the one hand, when the tube Iilb is formed of regenerated cel organic substances may be separated from aque lulose and the diffusate is an aqueous solvent, ous or non-aqueous. organic; solutions by use of a the rate of evaporation of water through the re semi-permeable hydrophobic tubing, while on the generated cellulose tube I812 is the same as the rate of evaporation from the same solution con 30 other hand water-soluble substances maybe sep arated from aqueous solutions by use of a hydro tained in a bath. In other words, the rate of philic tubing. Accordingly, the present appara evaporation appears to be independent of the tus may be used for separating inorganic or or membranes. ‘This appears to be due to the fact that the water diffuses in the wall of the tube 35 ganic crystalloids from their solutions, or for separating crystalloids from colloids, or for sepa I81; and evaporates from its external surface. rating inorganic substances from organic sub Thus, the present invention provides a process stances, or for separating organic ‘liquids from and apparatus by which the dialysis can be car aqueous or non-aqueous solutions. In particu ried' out simultaneously with the concentration of the dialyzate so that the decrease in the rate 40 lar, the apparatus is applicable for the separa tion of glycerine, butylene glycol, citric acid, su of dialysis resulting from dilution of the diilusate gar and inorganic salts and the like, from their can be substantially retarded or prevented. aqueous solutions. ' _ ‘ ' ' Preferably, the air which is caused to flow over the tube |8c is'air heated to an elevated tem perature of the boiling point of Water, but pref erably between 50 and 60° F. The heat trans ferred to the dialyzate is thus advantageous in .The heating of the dialyzate from 70 to 100° C. serves a four-fold purpose: (a) to continuously concentrate the dialyzate since water is evapo rated in the evaporator; (b) to increase the rate of dialysis; (c) to eliminate dissolved air and air bubbles; (d) to sterilize the dialyzate and pre preventing further fermentation and increasing ‘the rate of dialysis. Any conventional air blower vent further fermentation. . and air heater may be employed. 50 The apparatus has many advantages, namely, For treating aqueous liquid compositions, the the dialyzing membranes being in the form of a tubes I8, I81: and l_8b' may be formed of any hy drophilic ?lm-forming material, such, forexam ple, as parchment paper, tubes made from leather waste as sold under the trade names “Brech tee ” and “Naturin” and tubes made from any ?lm-forming non-?brous oellulosic materials as a class. ,For the treatment of aqueous ?uid com positions where it is desired to cause the diffusion and separation of water or water-miscible or ganic compounds from inorganic or organic sub, stances whether liquid or solids, there is prefer ' ably employed a hydrophilic cellulosic tube such, tube are more self-supporting than ?-at sheets and they can-be readily anchored atv each end without danger of leaks. When a tube breaks, 55 the liquid may be quickly drained from the ap paratus and a tube replaced without dismantling ' the ‘ entire apparatus. Since the tubes are not constricted at the entrance or exit ‘(where they are joined to the headers, the ?ow of liquid there 60 through is not retarded and there is no. tendency for sediment to collect inside the tube; further, a rapid ?ow can be maintained through the tubes. -Thus, there is provided a means for continuously concentrating the dialyzate while preventing the for example, as one formed of regenerated cellu lose ‘or cellulose hydrate which has been pro 65 rate of dialysis from dropping too rapidly, there by resulting in an increase in the yield. duced by regeneration from viscose or' from solu Since certain changes in carrying out the above tions of cellulose in inorganic or organic solvents process and in the constructions set forth, which or from cuprammonium cellulose or by the de esteri?cation of cellulose'esters such as, by the denitrationof cellulose nitrate, also membranes formed of alkali-soluble, water-insoluble cellu embody the invention, may be made without de parting from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be. lose ethers, gelatine (insolubilized), casein, al interpreted as illustrative and not in a limiting ginates, and the like ?lm-forming hydrophilic' sense. plastic materials. Such tubes are employed'in 75 Having described my invention, what I claim 2,411,285 ' . ' as new and desire to secure by Letters Patentis: 1. An apparatus for the dialysis of solutions comprising, in combination, a chamber, a multi plicity of tubular dialyzing membranes compris ing outer tubes of relatively large diameter and _ tubes of relatively small diameter, disposed in said tubes of large diameter, means spaced within said chamber supporting said tubular dialyzing membranes, means to pass the solution to be dialyzed through the outer tube into contact with onesurface of the inner tube, means to pass an otherliquid through the inner tube into contact with the ‘other surface of the inner tube, and‘ means to continuously concentrate the solution. being dialyzed so as to increase the rate of di alysis. ‘ 2. An apparatus for the dialysis of solutions comprising, in combination, a chambena multi 8, , i . being connected to the inner headers, means to pass a solution through the- inner tube, means to pass a diiferent solution through the .space between the inner and the outer tube, and insJanS to pass a. ?uid on the outside of the outer u e. - 4. An apparatus according to claim 3 in which ' . there is provided means for passing air over the surface of, the outer dialyzer tube so as to eva porate liquid from the surface of said tube. 5. A process‘ for the dialysis of solutions com prising passing the solution to be dialyzed into contact ‘with one surface of a dialyzing mem brane in the form of a tube, passing another liq? " uid into contact with the other surface of said tube, and continuously concentrating the solu-‘ tion being dialyzed at a point spaced from the dilalyzing membrane, and continuously recircu lating the concentrated solution, whereby the plicity of tubular dialyzing membranes, compris concentration gradient between the dialyzate and 20 ing outer tubes ofsrelativeiy large ‘diameter and the di?usate is maintained at its-highest level tubes of relatively small diameter disposed in said throughout the dialysis process. tubes of large diameter having tubular support 6. A process for dialyzing solutions comprising for the outer tube comprising an, open mesh fab- ‘ passing the solution to be dialyzed through an ric, disposed therein, means spaced'within said outer tubular dialyzer, in contact with an inner chamber supporting said tubular dialyzing mem 25. tubular dialyzer which is concentric with the ?rst branes, means to pass the solution toqbe dialyzed tubular dialyzer, passing another liquid through through the outer tube into contact with one sur and in contact with the inner tubular dialyzer, face of the-inner tube, means to pass another and passing air over the‘external surface of the liquid into contact with the other surface of the outer tubular dialyzer whereby a liquid is caused 30 inner tube, and means to continuously concen to be evaporated from said dialyzer. trate the solution being dialyzed so as to increase 7. A process for dialyzing solutions comprising the rate of dialysis. passing the solution to be dialyzed through a tu 3. An apparatus for thedialysis of solutions comprising, in combination, a chamber having inner and outer headers disposed transversely adjacent each end and de?ning a space between bular dialyzer of relatively large diameter in‘ with tubular dialyzer of smaller diam 3.5 contact eter which is disposed inside said larger tubular dialyzer, passing another liquid through and in them, dialyzing membranes in the form of inner contact with the tubular dialyzer of smaller di and outer concentric tubes of different diameters ameter, and passing a third ?uid over the exter disposed in said space and connected at each 40 nal surface ofithe. larger tubular dialyzer. end to said headers, the inner tube being con JUSTIN ZENDER. nected to the outer headers and the outer tube ' '