INDUSTRIAL AND ENGINEERING CHEMISTRY
Literature Cited Amagat, Ann. chim. phys., 29,58 (1893). Beattie, Hadlock, and Proffenberger, J . Chem.Phys., 3,93 (1935). Beeck, Ibid., 4, 680 (1936). Brown, Lewis, and Weber, IND.ENQ.CHEM.,25,325 (1934). Brown, Souders, and Smith, Ibid., 24, 514 (1932). Bryant, Ibid., 25, 820 (1933). Cope, Lewis, and Weber, Ibid., 23, 887 (1931). Deming and Shupe, Phys. Rev., 37, 638 (1931); 38, 2245 (1931).
Deschner, doctoral dissertation, Univ. Mirh., 1934. Edmister, IND.ENQ.CHEM.,28, 1112 (1936). Eucken and Liide, 2. physik. Chem., B5, 413 (1929). Eucken and Parts, IbiU., B20, 184 (1933). Haas and Stegeman, J . Phys. Chem., 36, 2126 (1932). Kay, IND.ENG.CHEM.,28, 1014 (1936). Kay, unpublished data. Keenan, Steam Tables, New York, Am. Soc. Mech. Engrs., 1930.
Keyes and Burke, J . Am. Chem. SOC.,49, 1403 (1927). Kvalnes and Gaddy, Ibid., 53, 397 (1931).
VOL. 30. NO. 3
Lewis, IND.ENQ.CHEM.,28,257 (1936). Lewis and Luke, Ibid., 25, 725 (1933). Lewis and Luke, Trans. Am. SOC.Mech. Engrs., 54, 55 (1932). Lewis and Randall, “Thermodynamics,” New York, McGrawHill Book Co., 1923. Iindsay and Brown, IND.ENO.CHEM.,27,817 (1935). Massen and Dolley, Proc. Roy. SOC.(London), 103, 524 (1923). Newton, IND.E m . CHEM.,27,302 (1935). Newton and Dodge, Ibid., 27, 577 (1935). Perry and Herrman, J . Phvs. Chem., 39, 1189 (1935). Rotinjanz and Nagornow, 2.physik. Chem., A169, 20 (1934) Sage and Lacey, IND.EXQ.CHEM.,27, 1484 (1935). Sage, Webster, and Lacey, Ibid., 29, 658 (1937). Selheimer, Souders, Smith, and Brown, Ibid., 24,515 (1932). Thayer and Stegeman, J. Phys. Chem., 35, 1.505 (1931). Thomas and Young, Trans. Chem. SOC.,67, 1071 (1895). Watson and Nelson, IND.ENQ.CHBM.,25, 880 (1983). Watson and Smith, Natl. Petroleum News. July 1, 1936. Young, Phil. Mag., [ 5 ] 47, 353 (1899). i37j Young, 2. physik. Chem., 29,193 (1899). RBCEIVDD September 29, 1937.
ORGANOLITES Organic Base-Exchange Materials HARRY BURRELL Ellis-Foster Company, Montclair, N. J.
T
The suggestion is made that the orAdams and Holmes (1) conHE phenomenon of base ganic counterparts of zeolites be called ceived the idea of purifying water exchange has been known since 1850 (29) when Way by synthetic resins prepared from sorganolites. types Of these polyhydric phenols and formalfirst showed that cations were have been studied- They are dehyde. This is probably the absorbed by soils. However, the discovery that bases were muresistant to attack by waters of widely first instance of a truly synthetic varying pH and are capable of hydrogenorganic base-exchange material. tually exchangeable (12, 19) is ion exchange if regenerated with acids. A similar product was reported usually credited t o Eichorn by Kirkpatrick (15A). Carleton (1858)n Although the Of A comparison with inorganic zeolites is Ellis suggested that all base-exWay applied to soils (in which both zeolites and humus a r e given. A theory of basemexchange acchange substances of organic oritivity is offered, and several applications known to base exchange, 7 , 16, gin i e called “organo~ites” to distinguish them from the in22, 28)) commercial exploitation are suggested. organic zeolites. of the reactions has been conResearches carried out in this fined almost entirely to zeolites laboratory have led to the development of synthetic organic of which the first commercial application for water softening base-exchange materials which show certain advantages over was patented by Gans (11) in 1906. Since that time the dethe phenol-aldehyde type and which possess qualities such as velopment of zeolites has progressed steadily until today their cheapness, high exchange capacities, and resistance to aggresuse is widespread. sive waters which indicate that they may be of considerable The organic or humus constituents of the soil have been value industrially. These organolites are prepared by renderinvestigated by several workers (18) from a scientific standing initially water-soluble wood extracts, especially those of point, especially as to effect of soil base exchange on plant life the tannin type, insoluble by treatment with concentrated and soil acidity (16). Recently the use of humates for water acids-for example, sulfuric acid. They will exchange either purification was suggested by Fischer and Fuchs ( I O ) , who sodium or hydrogen ions for calcium or magnesium, and exstated that water can be softened by the sodium humates hibit some increase over initial capacity with each of the first from humic acid of brown coal, and by Borrowman (6) who few regeneration cycles. percolated water through a granular bed of lignite or brown coal and regenerated the bed in the usual manner with sodium chloride brine. Modified humates, prepared by the action Theory of Organolites of strong reagents such as sulfuric acid or zinc chloride on Why such materials exhibit base exchange is not definitely peat, lignite, or wood, have also been described in several known. In the case of the polyhydric phenol-formaldehyde foreign patents (60,68). The use of humates is, however, resins, it is probable that large molecules are built up in the not very satisfactory because of the rather low base-exchange way usual for phenol-formaldehyde condensations (9) to capacity and a characteristic color throwing or imparting of a yellow to brown tint to the treated water. This latter defect produce substances which are capable of base exchanging in a manner similar to that of humus or lignin derivatives-that may be overcome, according to Borrowman (6) who treated the humic substance with sodium aluminate, and to Tiger and is, through functional phenolic groups (16, 17, 28). Goetz (67) who used chromium salts as the color stabilizers. When tannins are treated with concentrated sulfuric acid,
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INDUSTRIAL AND ENGINEERING CHEMISTRY
a number of reactions undoubtedly occur simultaneously. Dehydration, oxidation, sulfonation or sulfation, and polymerization all play a part in insolubilization. It may be noticed, incidentally, t h a t this is rather anomalous since sulfonation is a well-known method for rendering organic substances water soluble. At any rate, the end effect is evidently the formation of molecules, which are of such size as to be water insoluble and which contain groups such as hydroxyl or sulfonic which are capable of salt formation. These functional groups probably react with cations and hold them insoluble until released by the mass action of the regenerating solution (a).
Phenol-Aldehyde Resins The work of Adams and Holmes (1) of softening water with the quebracho-formaldehyde product was repeated, and the resin was found to have definite base-exchanging power. Although the resin was prepared according to the directions of the original investigators, the method of determining the capacity differed slightly. It was desirable to use a procedure which would (a) be applicable to a large number of diverse products to give comparative data, ( b ) provide laboratory data indicative of possible operating conditions with reasonable accuracy, ( e ) require a minimum of time and material per determination, and (d) require a minimum of “impure” (artificially hardened) water for testing. The method used, which is a composite of various schemes given in the literature, was as follows: The base-exchange materials were ground, usually with a mortar and pestle, and screened through 20 on 40 mesh sieves. The classified substance was given a preliminary washing by decantation with distilled water to remove colloidal and semicolloidal fines, and the wet slurry was poured with excess water into a glass tube 2.0 cm. in diameter t o form a settled and drained column 10.0 cm. high. The glass tubes were constricted at one end to about 1.5 cm. in diameter, and into this cone-shaped section was fitted a perforated porcelain plate 2-cm. in diameter. A very thin asbestos mat was placed on the plate in the manner ordinarily used in preparing a Gooch crucible, except that suction was not used. This supported the column of material t o be tested; on top was placed another perforated plate which served to distribute the inflowing water and thus minimize channeling. The prepared filter bed was further washed by allowing distilled water to drip through it from a separatory funnel. It was then tested by allowing a solution of known hardness (about 400 p. p. m.) t o flow through from a dropping funnel, usually at a rate of about 200 cc. per hour. The effluent was collected in 50-cc. portions and was titrated with standard soap, according to the method of Scott (21). When acid was used as the regenerant, the softened water was neutralized with 0.1 N sodium hydroxide, using bromothymol blue as indicator, before titrating with soap solution. When the effluent contained 5 or more p. p. m. hardness as calcium carbonate, the column was regenerated by allowing about 250 cc. of 10 per cent sodium chloride to flow through in a period of 1 hour and was then flushed with distilled water; the determination was repeated three times. This procedure was used in testing all the materials discussed in this pa er, unless otherwise noted. $he hard water was prepared by dissolving the appropriate amount of calcium chloride or calcium sulfate (no appreciable difference was found by varying the anion) in Montclair, N. J., tap water to reach a hardness of 400 p. p. m. From the volume of water treated per cycle and the volume of material used (31.4 cc.), the capacities can be calculated. Quebracho-formaldehyde resin was made by dissolving 100 grams of sulfited quebracho extract in 500 cc. of water, adding 500 cc. of water and 200 cc. of 40 per cent formalin, and heating t o boiling. Fifty cubic centimeters of concentrated hydrochloric acid diluted with 150 cc. of water were added with rapid stirring, and the entire solution quickly set to a soft gel. This gel was broken up and washed with water. When an attempt was made to use the undried material as a filter bed, it clogged, and the water percolated through at a negligible rate. The gel was dried at 40” C. t o form a hard, dark brown, brittle resin. A filter of the material softened an average of 700 cc. of 400 p. p. m. water. This represents substantially the same exchange capacity as was found by Adams and Holmes (1,Table 11)if corrections are made
359
for variation in mesh size (4), for hardness of test water, and for difference in volume of the test bed. If the resinification was carried out at room temperature, gelation took place with syneresisafter about 2 minutes. The product dried to a light red powder which was too finely divided to allow percolation through a filter bed. No gel was produced if the hydrochloric acid was replaced with ammonium hydroxide.
Other Phenolic Constituents Several other tanning materials were reacted with formaldehyde in the same proportions and by the same procedure as with quebracho. These data are shown in the following table, together with the amount of 400 p. p. m. hard water softened per column of resin (2 em. X 10 cm.), when 250 cc. of 10 per cent sodium chloride were used for regenerating: Tannin Logwood extract Hematin Fustic Sumac Chestnut extract Tannic apid Gallic acid
Form Solid Crystal Crystal Powder Powder Powder Powder
Cc. of Water Softened 200 None 400 None None None None
It is evident that tannin-formaldehyde resins are not universally applicable to calcium exchange. Apparently only tannins of the catechol type produce resins which w i l l soften water. This conclusion is verified by Table I1 of the Adams and Holmes paper as well as by the above table. All resins which are recorded as having absorbed calcium ions are of the catechol type, whereas chestnut extract, sumac, and tannic and gallic acids (pyrogallol type) softened no water. Some evidence in favor of the theory that the phenolic groups are functional in the absorption is presented by a comparison of the logwood-formaldehyde product with that from hematin (the oxidation product of the hematoxylin which is the coloring matter of logwood). Base exchange ceases when the phenolic groups are presumably destroyed by oxidation.
Other Resinifying Bodies Formaldehyde is not the only substance which condenses with phenols and tannins to produce insoluble resins. Phenolacetaldehyde resins do not usually “heat harden” or reach the C-stage, so that tannin-acetaldehyde resins might not be expected to become sufficiently insoluble to be useful as b a s e exchange agents. However, when acetaldehyde was substituted for the 40 per cent formalin in preparing a quebracho resin, a hard dark-brown solid separated after boiling under reflux for 30 minutes. A column of the material softened 500 cc. of 400 p. p. m. hard water. The use of n-butyrddehyde or furfural gave resins which would not absorb calcium. Furfural condensation products with resorcinol or aniline were also inactive. When quebracho extract was refluxed for 10 hours with 2 parts of acetone and 0.5 part of concentrated hydrochloric acid, and the resulting sirup was poured into 2 liters of water, a precipitate was obtained which, when dried, screened, and tested, softened 200 cc. of 400 p. p. m. hard water (200 cc. of 10 per cent sodium chloride were used for regenerating the filter bed). Alkyd, urea-formaldehyde, and rosin-maleic anhydride represented other species of resins tried, but none showed a sodium-calcium base exchange.
Sulfuric Acid-Insolubilized Materials The first of the vegetable extracts to be acid-treated was sulfited quebracho.
the quebracho-sulfuric acid material, but its c a p a c i t y w a s not as great; the o p t i m u m w a s 6 0 0 cc. of 400 p. p. m. hard water for
1600-
9 1400w z b-
$ 1200z
tained. The following table 3 700gives the comparative capacities of the prod5 mucts of a few extracts 5 which have been tjso0 mixed with five times t h e i r w e i g h t of a n acid sludge from B white oil reEning and heated t o 80" C. (The reaction with zoo p e t r o l e u m s l u d g e is l e 3 4 5 6 not very exothermic.) PARTS H250, PER PART CHESTNUT EXT. The are again FIGURE2. VARIATIONOF Exexpressed a s v o l u m e CHANGE CAPACITY WITH RATIO OF of 400 p. p. m. hard SULFURICACID TO CHESTNUT w a t e r softened per EXTRACT filter column of o r ganolite; 250 cc. of 10 per cent brine were used for regenerating:
E
g400
3coc/'
u
Substance Reacting with &SOP Sulfited quebracho extract Chestnut extract Cutch .Hemlock cellulose sulfite liquor Hemlock cellulose sulfite liquor (Bindexa) Poplar cellulose sulfite liquor Pine sawdust Alpha flock Cane sugar
Cc. of 400 p. p. m. Water Softened 1650 600 850 700 1300 850 400 150 150
"Bindex" is the trade name for a commercially prepared dried hemlock cellulose sulfite liquor; the other liquors used were obtained in the liquid state and dried in the laboratory.
It is evident that
Vegetable Extract
Cc. of 400 p. p. m. Water Softened
Quebracho Bindex Chestnut
1650 1500 900
B wider variety of wood extracts may be
used with acids for preparation of water-softening media than is possible by resinification with formaldehyde. Not only catechol and pyrogallol tannins but also the pseudo tannins such as sulfite liquors are applicable. The latter are rich in lignins which are known to base exchange (16). The possibility that the active principle of these products is merely carbon is improbable from evidence in the above table. It is apparent that the capacity decreases with the extractive content (e. g., pine sawdust and alpha flock); further, when these materials are charred by heat alone, the
Acid Regeneration An important advantage of organolites over zeolites is that they may be regenerated with an acid whose anion constituent forms a soluble salt with the cation exchanged for the hydrogen ion. There is some evidence that zeolites may be incapable of reversibly exchanging hydrogen ions ( 1 4 ); whether or not this is theoretically possible, it cannot be practically realized with zeolites because they are attacked by the acid, and the exchange capacity is lowered (3). The acid-
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INDUSTRIAL AND ENGINEERING,CHEMISTRY
361
and in feed-water heaters. To overcome these after effects, insolubilized organolites, as well as the Adams and Holmes “recarbonation” is resorted to; that is, carbon dioxide is quebracho-formaldehyde resin, are saturated with hydrogen dissolved in the water in sufficient amount to keep the calions as prepared and will exchange them for calcium ions cium in solution (IS). Present installations usually burn directly. They may be repeatedly regenerated by a dilute coke or other fuel for a source of carbon dioxide. If it is acid solution-for example, 5 per cent sulfuric. The effluent deemed more economical to soften a given water by the lime from such a treatment is not truly softened from the standprocess, it may be recarbonated by passing water containing point of soap consumption, since fatty acids are precipitated carbonates through an acid-regenerated organolite and comwhen soap is added; but the fact that calcium or magnesium bining the effluent with that from the lime treatment. has been removed from a hard water is easily shown by adExperiments illustrating this possibility were performed by justing the p H to 7 (e. g., by adding dilute alkali) before tiregenerating columns of organolite (10 om. long and 2 cm. in trating with soap, whereupon a zero hardness determination diameter) with 250-cc. portions of 5 per cent sulfuric acid. results. Such an acid water may presumably be used in A test solution was prepared by bubbling carbon dioxide certain instances, where metal-free water is desired, without through a suspension of calcium carbonate in tap water and neutralizing it. The substitution for distilled make-up water filtering off the excess lime. The resulting hard water was for lead storage batteries is a possibility. diluted so as to contain 400 p. p. m. hardness and 0.473 mg. An impressive application of this process is in alkalixiity bicarbonate ion per cc. (the latter was determined by titracontrol and bicarbonate removal. The contributory eletion with 0.1 N hydrochloric acid). The following table oonment of zeolite-softened waters in causing caustic embrittletains data expressing the capacities as volumes of the water ment in boilers is well known (24). When water with carbonwhich were softened and decarbonated by 31.4-cc. filter beds ate or temporary (bicarbonate) hardness is softened with of the materials. zeolite, the effluent contains sodium carbonate or bicarbonate which hydrolyzes to sodium hydroxide Organolite Cc. of Water Purified ) u n d e r the temperatures and pressures Acid sludge-Bindex 1900 Quebracho extract-sulfuric acid 1800 axisting in steam boilers. There are Quebracho-formaldehyde 500 cases where sulfuric acid has been added to such waters to destroy the carbonates Another field for acid regeneration is before adding them to the boiler; this suggested by the recent papers of Cereis accomplished a t the c o s t of e x t r a cedo and his co-workers (8), who used chemical and apparatus for correct dosage zeolites in extracting vitamin B1 from and with the danger of a ruinous excess natural sources. Since they gave the being applied. It is an easy matter to (gel) zeolite an acid wash and carried out soften a water containing, say, calcium the procedure a t about p H 4.0, organobicarbonate, and a t the same time to lites should be more amenable to the eliminate the bicarbonate ions by using process. an acid-regenerated material. T h i s i s brought about by virtue of hydrogen exProperties Other than changing for calcium, with the resultExchange Capacity a n t f o r m a t i o n in the treated water Many characteristics determine the .of carbonic acid which spontaneously value of a base-exchange medium bed e c o m p o s e s into water and carbon sides the amount of calcium absorbed dioxide. The latter is easily removed b y t h e t h o r o u g h l y sodium-saturated by aeration, and c o n s e q u e n t l y t h e material. Although this “ultimate exoriginal hardness is removed and a rechange value” is invaluable in comparing duction of total solids is actually accoma series of widely varied products, many of plished. which may have zero capacity, Tiger (26) If the raw water contains a mixed discusses nearly a score of other qualitype of hardness-e. g. sulfate as well as ties which interdependently determine bicarbonate-the effluent will contain an fitness for use. It was beyond the scope acid which must be neutralized by some of this work to consider all of them; hence, convenient method since aeration will many routine determinations remain for not effect its removal. The possibility t h e f u t u r e . Interesting comparisons of using the anion-exchanging resins dewere obtained in a few cases, however. scribed by Adams and Holmes ( I ) is inThe salt consumption, or amount of dicated here. hardness removed per pound of salt used I n certain cases it would be advantafor regenerating, is an important factor. geous to use the carbon dioxide-containing The stoichiometric amount is never obwater as such, rather than to aerate it. tained in actual operation; therefore, the I n softening water by the lime-soda procamount of excess salt required affects the ess, especially in the cold, the reactions o p t i m u m economic working conditions are sluggish and i t is difficult to obtain profoundly. an effluent of low noncarbonate hardness The experimental method used in deby using the theoretical amount of lime. termining this characteristic was modified Hence, “overtreatment” is resorted to; s l i g h t l y f r o m the foregoing general that is, an excess of lime is added which m e t h o d . The apparatus is shown in usually results in the presence of calcium Figure 3: hydroxide in the effluent. This is objectionable because of after-precipitation Tubes I and I1 contain 10-cm. diameter and formation of scale deposits in pipe filter beds of organolite, 2 cm. in diameter. FIGURE 3. S O D ~ CHLORIDE M ;lines, principally in hot water systems The material, screened through 20 on 40 mesh CONSUMPTION APPARATUS
INDUSTRIAL AND ENGINEERING CHEMISTRY
362
sieves, is supported on a 2-cm. perforated porcelain plate which is separated from the lower one-hole stop er by glass beads, E . Into this stopper is inserted a T-tube whic! may be used for drainage into cylinders D and D' or (with proper setting of stopcock C) for directing a stream of wash water upward through the bed. On top of the column lies another perforated late for distributing the water flowing downward through the tuie inserted in the uper stopper. Stopcock C is used with the various clam s so that %ardwater (from bottle A ) or brine (from bottle B)m a y t e passed either upward or downward through the columns. At the start of the cycle the upper stopper and perforatedplate were removed, and an identical glass tube, F , was connected with the one containing the organolite by a short length of rubber tubing, as shown on tube 11. Hard water was introduced at the bottom,
'
-
a
In
QUEBRACHO-ACIDSLUDGE
4
i
/
-GREENSAND
ZEOLITE
1
C. QUEBRACHO-FORMALDEHYDE
ot
0
I
I
I
1
5 IO 15 20 POUNDS NaCl PER CU.FT.
I
25
I
FIGURE 4. VARIATION OF BASEExCHANGE CAPACITY WITH SALTCONSUMPTION
washing the organolite granules upward until the suspended volume was about 45 cc. When the granules were thoroughly stirred, the flow was stopped and they were allowed t o settle; the column was then drained. (It was this settled and drained bed that'was adjusted to the 10-cm. height.) Tube F was removed, and the perforated plate and stopper were replaced (as in tube I). The desired amount of sodium chloride solution (of 10 per cent concentration for more than the equivalent of 15 pounds of salt per cubic foot, and 5 per cent for less) was run downward through the bed. The stopcock was then set so that the 400 p. p. m. hard water would percolate downward at the rate of 300 cc. per hour (controlledby Hoffman clam s G and G'), and the first 50 cc. were discarded as wash water. Each succeeding 100cc. portion was titrated for hardness with soap, and, when an effluent containing 5 p. p. m. hardness was obtained, the cycle was repeated. From the average of the volumes of water softened on three determinations, the kilograins of calcium carbonate removed for each amount of salt used were determined by the following formula:
E
=
H 28320 15.43 VH V .= 0.000436 7 106 B 1000
where E
= exchange capacity, kilograins CaC03 per cu. f t . V = volume water softened, cc. H = hardness of water, p. p. m. (400) B = 'volume of test bed, cc. (31.4)
VOL. 30, NO. 3
200 cc. of 10 per cent sodium chloride brine which was adjusted to various p H values (determined colorimetrically with La Motte indicators and standards) with dilute hydrochloric acid or sodium hydroxide; the amount of calcium chloride solution of 400 p. p. m. hardness (adjusted to the same p H as the regenerant) which was softened to less than 5 p. p. m. hardness by the column was then determined. The data are plotted in Figure 5. I n the p H range of 7 to 4 there is no appreciable variation in exchange capacity. On either side of this range, for the values investigated, the capacity appears to increase directly with the p H value. The change of capacity with p H is similar to that of zeolites but not so pronounced. Behrman and Gustafson (3) determined the decrease in capacity with a pH drop from 7.8 to 6.0 of greensand, high-capacity greensand, and gel zeolites (under different conditions from those used here), and found percentage decreases of approximately 25, 43, and 38 per cent, respectively. The same p H change produced only a 7 per cent decrease in capacity of the organolite investigated. Beyond rather narrow limits the capacity of zeolites falls off markedly with either an increase or decrease in p H ($6); over the rather wide range of p H 11 to 2 the capacity drops 33 per cent for the organolite. No tendency to disintegrate, dissolve, or throw color was noticed in either the acid or alkaline condittons. A simple qualitative test for color throwing was made by immersing a small quantity of organolite (previously subjected to several exhaustion and regeneration cycles) in ten times its volume of distilled water for 6 days, and noting whether any ye!low or brown coloration was imparted to the water. No color was thrown by quebracho-sulfuric acid, quebracho-acid sludge, or hemlock sulfite liquor-acid sludge materials, but chestnut-sulfuric acid and quebracho-formaldehyde materials colored the supernatant water noticeably. Quebracho-formaldehyde also showed a growth of greenish gray mold, a phenomenon which was likewise observed whenever a wet sample of this material was stored in a closed container. The other substances were inoculated with this mold but would not support the growth.
4L 2
700
800
9
600
CC. 400 PPM. WATER SOFTENED
With the test bed used, each 10.0 cc. of 5 per cent sodium chloride solution was equivalent to 1 pound of salt per cubic foot. Determinations were made on quebracho-acid sludge, Bindex-acid sludge, quebracho-formaldehyde resin, and greensand (Zeodur) materials. The results are plotted in Figure 4. Since it is not customary to regenerate with more than 10 pounds of salt per cubic foot, the left-hand portion of the graph gives an indication of capacities under operating conditions. At 3 and 8 pounds of salt per cubic foot the acid sludge materials possess a higher capacity than greensand; that of the quebracho-formaldehyde resin is less than the greensand. The effect of pH was studied by repeatedly regenerating a 2 X 5 em. filter bed of Bindex-acid sludge product with
FIGVRE 5. VARIATION OF CAPACITY OB SULFITE LIQUOR-ACID SLUDGE ORGANOLITE WITH PH
I n the field of water softening where organolites might compete with zeolites, two other factors are worthy of note. The density of the organolites (measured dry, tamped down in a graduate) is 40-45 pounds per cubic foot, a value which compares with 45-50 pounds for gel zeolite and 80-90 pounds for greensand. The actual density when wet would be somewhat greater for the first two because of absorbed water. Since softening apparatus is designed with volume in mind and since capacities are regularly stated in terms of volume, a low density would be an economic advantage to a purchaser who buys on a weight basis; on the other hand, a
MARCH, 1938
INDUSTRIAL AND ENGINEERING CHEMISTRY
more dense material is less liable to be carried away by suspension in the backwash. A possible defect of organolites is the low physical strength, since the granules are somewhat soft when wet. A quantitative estimate of resistance to abrasion has not yet been made.
Conclusion Experiments on preparing the acid-insolubilized material on a semiplant scale substantiate the smaller scale work as does actual softening of water in a portable size unit. Although the work cannot be said to have progressed from the experimental stage, the evidence ostensibly indicates that the organolites may be of some utility in the fields of water softening and acid regeneration and also, if selectively absorptive materials are developed, for special cation absorption.
Acknowledgment The author wishes to thank the Ellis-Foster Company and the Newark College of Engineering for permission to publish the data. The Permutit Company kindly furnished zeolite samples, and the Champion Fibre Company the Bindex and chestnut extract.
Literature Cited (1) Adams, B.
A.,and Holmes, E. L., J . SOC.Chem. Znd.. 54, 1-6T
(1935): British Patents 450,308 and 450,309 (July 13, 1936); U. S.Patent 2,104,501(Jan. 4, 1938).
(2) Austerweil, G.,J . Soc. Chem. Znd., 53, 185-9T (1934). 28, 1279(3) Behrman, A. S., and Gustafson, H., IND. ENQ.CHEM., 82 (1936). (4) Bird, P., Colburn, F., and Smith, F., Ibid., 25, 564 (1933). (5) Borrowman. G., U.8. Patent 1,793,670(Feb. 24, 1931). (6) ZEid., 1,994,682(March 19, 1935).
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(7) Burgess, P. S.,and McGeorge, W. T., Science, 64,652-3 (1926). (8) Cerecedo, L.R., Hennessy, D. J., Kaszuba, F. J., and Thornton, J. J., S. Am. Chem. Soc., 59, 1617-22 (1937). (9) Ellis, Carleton, IND.ENQ.CHEM.,28,1141-2 (1936);“Chemistry of Synthetic Resins,” Chap. 14, New York, Reinhold Publishing Corp., 1935. (10) Fischer, F., and Fuchs, W , Brennstof-Chem., 8, 291-3 (1927). (11) Gans, R., German Patent 197,111 (1906);U. S.Patents 914,405 and 943,535 (March 9 and Dee. 14,1909). (12) Hoover, C. P., Ohio Conf. Water Purification, 13th Ann. Rept., p. 40 (1933). (13) Hopkins, E.S., “Water Purification Control,” 2nd ed., p. 162, Baltimore, Williams and Wilkins Co., 1936. (14) Kappen, H., and Rung, F., 2. Pflanzenernithr.DCngung Bodenk,, SA, 345-73 (1927). (15) Kelley, W. P., and Brown, 5. M., Soil Sci., 21, 289-302 (1926). (l5A) Kirkpatrick, W.H., U. 5.Patent 2,094,359(Sept. 28, 19371. (16) McGeorge, W. T.,Ariz. Agr. Expt. Sta., Tech. Bull. 30,181-213 (1930): 31,215-51 (1931). (17) Mitchell, J., J . Am. SOC.Agron., 24, 256-75 (1932). (18) Muller, J. F.,Sod Sci., 35,229-37 (1933). (19) Nordell, E , Mich. State Coll. Agr., Eng. Espt. Stu. BUZZ.61,1525 (1935): reminted bv Permutit C o . (20) N. V. Oc’trooien MaaGchappij “AEiivit,” French Patents 778,922(1935),784,348 (1935),and 805,092 (1936). (21) Scott, W. W., “Standard Methods of Chemical Analysis,” 2nd ed., revised, p. 559,New York, D. Van Nostrand Co., 1917. (22) Sigmond, E., Mutematik. TermBszett. &tesit8, 43,51-78 (Hung.). 79-80 (Ger.) (1926). (23) Sokolov, N., Mitt. staatl. Znst. esptl. Agron., Abt. Ackerbau (Leningrad), No. 20 (1929). (24) Straub, F. G., Univ. Ill., Eng. E s p t . Sta. Bull. 216 (1930). (25) Sweeney, 0.R.,and Riley, R., IND.ENQ.CHEM.,18, 1214-16 (1926). (26) Tiger, H.L.,J . Am. Water Works Assoc., 26, 357-70 (1934). (27) Tiger, H. L.,and Goetz, P. C., U. S. Patent 2,069,564(Feb. 2, 1937). (28) United’ Water Softeners, Ltd., British Patents 450,574 and 450,575 (1936). (29) Way, J. T., J . Roy. Agr. SOC.,11, 313 (1850); 13, 123 (1852). RECEIVED October 22, 1937.
Liquid-Level Control Apparatus I
R. E. HERSH, E. M. FRY,‘ AND M. R. FENSKE The Pennsylvania State College, State College, Pa.
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LTHOUGH a number of methods have been devised for automatically controlling liquid levels or liquid-liquid I interface levels, nearly all of them depend on floats a t the surface or a t the interface, or on a differential manometer mechanism to operate a switch or relay. The mechanism is sometimes rather bulky and requires a considerable amount of holdup of the liquids to ensure reliable control. I n this article simple and compact mechanisms are described for controlling interface levels or liquid levels which operate on the differences in electrical conductivity of the two liquids at the interface or of the liquid and air a t the surface. Such a device for controlling the interface level in a lubricating oil extraction tower using a number of different solvents has been in satisfactory operation in this laboratory for more than a year. The apparatus consists essentially of electrodes a t the interface and a means for utilizing the small current flowing through the solvent to operate a relay which, in turn, regulates the flow mechanism. One method of accomplishing this ,is illustrated in Figure 1. The electrodes are inserted from opposite ends of a specially constructed liquid-level gage on the extraction tower a t a point where the interface between the solvent and oil occurs, the electrode points being any-
‘ Present address, Standard Oil Development Company, Elizabeth, N . J.
where from 0.25 to 0.75 inch apart. To insulate the leads from the tower, 0.5-inch spark plugs with the grounded points removed are used, extensions being soldered or welded to the points protruding through the porcelain. These electrodes are part of a single-stage resistance-coupled amplifier circuit operating on 110 volts a. c. This circuit utilizes a type 37 or 37A three-electrode vacuum tube as an amplifier for operating a relay in the plate circuit. The external circuit then energizes a solenoid valve in the drawoff line from the tower. When the solvent layer is between the electrodes, its conductance is sufficient to produce a large grid-bias, and the plate current, therefore, is too low to operate the relay. However, as the oil builds up and insulates the electrodes from each other, a very weak current flows in the grid circuit through the 5-megohm resistor, and the plate current increases sufficiently to close the relay; whereupon, the solenoid valve is opened and the oil permitted to drain from the tower. The grid leak is indicated in Figure 1 as a variable resistance since, with different liquid-liquid systems, it may be desirable to employ a different size in order to vary the range through which the plate current fluctuates as an aid for positive relay action. However, the flexibility obtainable amounts to only a few milliamperes when the resistance is changed from 5 t o 1
