Adsorption Isotherms of Synthetic Resin Ion-Exchange Adsorbents ROBERT J. MYERS, JOHN W. EASTES, AND DONALD URQUHART The Resinous Products & Chemical Company, Inc., Philadelphia, Penna.
S POINTED out in a previous paper (12), the discovery of Adams and Holmes ( I ) in 1935 that synthetic resins
A
exhibited ion-exchange adsorption has refocused the attention of chemists on synthetic resins as truly synthetic organic base-exchange materials, and on resins as chemical compounds capable of specific chemical reaction, as opposed to the former emphasis on the physical properties of synthetic polymers. The patent literature and the commercial development of the resinous ion exchangers have grown rapidly (7, I d ) , while the fundamental investigations appear to be limited to those of Bhatnagar and co-workers (3, 4, Akeroyd and Broughton (2), Broughton and Lee (6), and Schwarts and co-workers (16). These investigators have examined the adsorptive character of a few simple phenolformaldehyde and amine-formaldehyde resins. Other than a brief reference by Griessbach (7) to the possible correlation of the pH-neutralization curves of substituted phenol-aldehyde resins and the practical application of such materials as hydrogen exchangers, no attempt appears to have been made to translate fundamental studies into practical application.
Ion-exchange adsorption on synthetic resins has been considered as a species of chromatographic adsorption, and brealrthrough capacities of adsorption columns have been correlated with adsorption isotherms determined under conditions which simulated those in the columns. The adsorption method developed in this work has been found useful for a rapid evaluation of new resins. Direct visual observation of chromatographic banding on synthetic resins is reported.
The evaluation of commercial exchange adsorbents in the laboratory offers an opportunity for a judicious interpretation of fundamental physicochemical characteristics of ionexchange substances in the correlation of easily determined quantities with practical exchange capacities. The present method of small-scale studies in laboratory columns under conditions simulating those found in large-scale exchanger beds becomes laborious and costly when hundreds of new products must be examined under a variety of conditions, such as concentrations and types of exchanging ions, regenerants, and regenerant ratios. While such studies in columns
must eventually be made before practical application is undertaken, the development of simple testing techniques based upon fundamental principles should not only obviate much of the labor involved in the evaluation of exchange adsorbents, but serve as well to clarify the mechanism of ion exchange. An attempt has been made to correlate adsorption isotherms with exchange capacity as determined in columns, and this paper is a preliminary report on an investigation into the character of ion exchange by synthetic resins in general.
Adsorption Isotherms and Chromatographic Banding The exchange phenomenon in a column of a synthetic resin ion exchanger was considered as a species of chromatographic adsorption (18, 19),in which a “band” of exchanged (or adsorbed) cation or anion moved progressively downward through the column. The “break-through” capacity, the point at which the exchanging ion first appeared in the column effluent, was regarded as the adsorption value for the resin in contact with a solution with an ion concentration equal to that of the original solution fed to the column. Such a picture of the adsorption is consistent with the observation that the hydrogen-exchange resin separated calcium from sodium when the two ions were present in a solution fed to the column. While the jet-black color of most hydrogen exchangers prevents the visual observation of such phenomena, certain anion-exchange resins, originally light orange in color, were noticed to form a reddish-orange band superimposed on a brown band when a mixture of hydrochloric and sulfuric acids was flowed through a column of the resin. Analysis revealed that the reddish-orange band was the pure hydrosulfate, the brown band the pure hydrochloride form of the resin. Wilson’s theory (19) of chromatography was examined and suitably extended as follows to apply to the calculation of the probable exchange capacity of a resin from a knowledge of the adsorption isotherm for the ion in question. Wilson showed that insertion of the appropriate boundary conditions into the differential equation,
leads to the discontinuous solution, for and
0 < 2 < vco/Mf(co), 2
> VC,/~f(C,),
62 = M j ( c o )
Q
=
0
(2) (3)
Equation 1 describes the adsorption changes occurring a t a point 2 cm. from the top of a column of adsorbent (containing M grams of adsorbent per centimeter length of column) 1270
INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1941
1001
1
I
I
I
I Ill1
I
I
I
I I I I I I
I
IO 100 Ce RESIDUAL CONCENTRATION, mq./100cc.
FIQURE 1. ADSORPTION OF ACIDS BY METAPHENYLENE DIAMINE RESIN (above) AND BY AMBERLITE IR-4 (below) EBB, data of Edwards, Schwattz, and Boudreaux
when a volume v of a solution of solute a t an initial concentration co is fed to the column; the adsorption isotherm for the given solute on the adsorbent is q / m = f(c), or Q = M f ( c ) , where Q is the number of millimoles adsorbed per centimeter length of column in equilibrium with a solution whose concentration is c. Equations 2 and 3 account in a satisfactory manner for the sharpness of the occurrence of bands. When a sufficient volume of solution, v, has been fed to the column to extend the length of the band, vc,/Mf(co), to I , the length of the column, break-through occurs. Since break-through is customarily expressed in terms of grams of adsorbate per gram of adsorbent, and since grams adsorbate vco Z M )'(I = grams adsorbent = capacity
a knowledge of adsorption isotherms should permit a calculation of break-through capacity of columns of adsorbents when break-through occurs. I n order to determine whether adsorption isotherms could be applied in this fashion to ion-exchange phenomena, the isotherms were determined in several anion- and cationexchange resins, and the calculated values derived therefrom were compared with the values obtained by direct measurement in exchange columns.
Determination of Adsorption Values Schwartz, Edwards, and Boudreaux (16) studied the variables involved in the adsorption of acids by a metaphenylene diamine-formaldehyde resin. The adsorption of hydrochloric acid and sulfuric acid was found to be influenced by the extent of developed surface, time of contact, initial concentration, and the nature of the drying of the resin. While Schwartz and eo-workers did not record the fact, their adsorption data give isotherms of the Freundlich type. Bhatnagar and associates (3, 4) investigated both phenolformaldehyde and amine-formaldehyde resins. Typical isotherms were obtained for the adsorption of inorganic and
1271
organic bases and acids from aqueous solution. The metaphenylene diamine resins are, in general, very low in exchange capacity (@, and the adsorption is influenced by the extent of developed surface. Cation-exchange resins were not studied by Schwartz and co-workers. T o compare exchange-capacity values calculated from adsorption isotherms with those obtained in columns, particularly when highcapacity cation- and anion-exchange resins were under study, i t was necessary t o re-evaluate some of the findings of Schwartz, Edwards, and Boudreaux with respect to the new resins. MATERIALS.For the study of the variables involved in the determination of adsorption isotherms, three typical resins were selected. One was a low-capacity metaphenylene diamine resin prepared as disclosed in U. S. Patent 2,151,883 (1). The high-capacity anion-exchange resin was Amberlite IR-4. The cation-exchange resin was a modified phenolformaldehyde resin, Amberlite IR-1. The general technique consisted in placing a weighed quantity of the dried resin in contact with a definite volume of a solution of electrolyte in a 250-cc. Erlenmeyer flask and mixing a t room temperature with stirrers activated by a line shaft. The solution was stirred for a definite time and quickly filtered, and the filtrate analyzed for the characteristic ion. Acids were determined by titration with 0.1 N sodium hydroxide (bromothymol blue indicator), chlorides by the conventional Mohr method, sulfates by titration with barium chloride and THQ indicator (17),and calcium by titration with potassium oleate (10). A few preliminary studies confirmed the findings of Schwartz and co-workers (16) that in a solution of acid the adsorbate was removed as whole molecules. The analytical work was then shortened in those cases to simple backtitration with alkali.
RESIDUAL
CONC€NTRATION,
my, /
1OOc.c.
FIGURE 2. EFFECT OF PARTICLE SIZE ON ADSORPTION OF HYDROCHLORIC ACIDBY METAPHENYLENE DIAMINE RESIN FREUNDLXCH ISOTHIIRM CONST~NTS Grading
k n
20/30 10.1 0.334
30/40 11.3 0.323
40/50 12.5 0.365
50/60
22 0.325
PREPARATION OF SAMPLE. The anion exchangers were studied in detail since preliminary investigations had shown that the manner in which the adsorption isotherms were determined was of much greater importance in this case than with the cation exchangers. The resins were dry-screened to a -20 40 grading, activated by treatment overnight with a 5 per cent sodium carbonate solution (20 cc. per gram), washed free of alkali, and air-dried. This product was used in both the adsorption isotherm determinations and in the column studies. EFFECTOF CONTACTTIME. Table I indicates that a practical equilibrium adsorption value is attained with both anion exchangers after 6-hour contact with either hydrochloric or sulfuric acid. I n view of these results the adsorp-
+
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
1272
Vol. 33, No. 10
tion isotherms were determined on 5-6 hour samples throughout the remainder of this work. -4few experiments on longtime contact revealed that a slow but measurable adsorption continued beyond %hour contact. Since this had also been noticed in the column experiments when operations were conducted a t an abnormally slov rate of flow, the additional adsorption was believed to be due to a slow diffusion into the interior of the resin, whereby active groups inside the resin particle came into play. The 6-hour contact time was therefore adopted as the value most consistent with normal column conditions. CONTACT T I M E ON ACID ADSORPTION^ Metaphenylene Diamine-HCHO Amberlite IR-4 Acid, p, ,p, ~ 1 . b : HC1, 608 HzSOI, 817 , HC1, 608 H?SOa, 817 Mg. Resin: 200 750 200 750 100 200 100 200 -Adsorption in mg. pcr gram-78.5 67 101.5 118.2 292 246 1-hr. contact 25.4 22.2 2-hr. contact 2 9 . 0 30.4 97.6 90 1 3 8 . 5 151.0 360 336 3-hr. oontaot 3 0 . 1 37.6 135 101 159 163.0 372 332 104 4-hr; oontaot 4 0 . 6 4 1 . 8 145 109 198' l 9 i : O 41'2 366 5-hr. contact 4 6 . 0 4 5 . 0 164 109 211 211.0 444 376 6-hr. contact 4 9 . 0 4 6 . 0 161 110 201 209.0 438 390 8-hr. contact 5 2 . 0 4 9 . 0 163 a Volume of solution, 120 cc.; resins graded t o -20 4- 40 mesh b Parts per million, m d l i t e r .
TABLE I. EFFECTOF
IO RESIDUAL CONCENTRATION,
FIGURE 3.
EFFECT OF PARTICLE SIZEO N ADSORPTION OF SULFURICACID BY METAPHENYLENE DIAMINE RESIN F R E U I D L I C H I S O T H E R V CONSTAXTR
Grading 20/30 la 6 95 n 0 600
=
log k
+ n log
11. EFFECTO F
C,
1500 1000 750 600 200 100 a
20.2 24.9 27.4 30.0 31.8 32.6
4.8 9.4 13.1 17.7 24.8 27.7
+
S.4;MPI.E \vEIGHT AND INITIAL CONCENTRATION O S hIETAPHENYLENE
304 P. P. .\I. CF u
SrtmpleWeight. hlg.
0 583
Initial Concn. of HC1 608 P. P. M. 912 P. P. ill. CF u CF u
,1216 P. P. M. CF u
408 P. P. M.
17.1 26.7 34.0 41.8 53.4 57.5
51.2 69.5 82.0 94.5 112.0 123.6
2.0 2.3 4.3 8.2 22.9 32.3
34.6 40.2 42.0 44.8 42.0 36.0
33.2 47.6 57.0 67.8 82.8 88.6
45.8 51.6 54.2 54.6 48.0 25.0
5-hour contact time, room temperature; 120-cc. volume of solution.
50/60 80 0 0 255
40/50 16 0 0 602
+
The data of Schwartz and eo-workers on sulfuric acid adsorption has been recalculated and is shown in Figure 1 to be normal. To obtain a reasonable "spread" in the adsorption values, it is preferable t o employ a constant weight of sample and to vary the initial concentration. A 200-mg. sample was selected as that weight which would not adsorb too small a n amount of acid when capacity \vas low, yet leave a reasonable amount of acid when capacity was high.
T.4BI.E
30/40 11 6
PARTICLE SIZE. The resins were crushed and screened to various gradings, and the adsorption for the two acids was determined. The results are illustrated in Figures 2 to 5. The dependence of the capacity of a metaphenylene diamine resin on developed surface had been observed by Schmartz, Edwards, and Boudreaux (16), but their data are insufficient for plotting or calculating an adsorption isotherm. On the other hand, Amberlite IR-4 shows practically no change in adsorption capacity when the particle size is 30 to a -70 100 grading. This reduced from a -20 behavior, as contrasted with that of the diamine resin, is in accord with the open, porous gel structure of the IR-4 resin as opposed to the hard, impervious appearance of the diamine condensate. TT7hile prolonged contact of the diamine resin with the solution might conceivably nullify the spread between the isotherms, the results obtained under such conditions would have no significance in the present investigation. CONCENTRATION OF SOLUTION.In order to obtain a spread in the adsorption values, a hydrochloric acid solution whose concentration varied from 304 to 1216 p. p. m. and a sulfuric acid solution whose concentration varied from 204 to 1224 p. p. m. were employed.
SAMPLEWEIGHT. Schwartz, Edwards, and Boudreaux (16) noted a variation in adsorption with initial concentration of acid but apparently failed t o realize its significance. The adsorption per gram varies (Tables I1 and 111)in an anomalous fashion with sample weight and concentration, but this is not surprising since adsorption is generally related to residual concentration of adsorbate; Figures 1 and 2 indicate that adsorption proceeds in a regular manner according to the Freundlich adsorption isotherm, log u
100 AC I O/ 140c t
"9.
56.0 61.6 62.3 63.5 58.4 41.6
CF
21
34.0 44.7 56.8 75.6 101.0 89.8
DIAMINE-FORXILDEHYDE RESIN=
Initial Concn. of HiSOa 816 P. P. 11. 1224 P. P. AI. CF 1L CF U 3.2 8.0 15.1 28.0 56.0 68.5
34.8 86.0 103.0 124.5 141.4 133.5
7.6 18.9 33.5 53.6 80.5 107
1632 P. P. h l . CF U
101 15.5 122.7 35.0 137.3 58.6 157.5 84.6 1 7 8 . 5 , 129 146.2 147
115 149 161 179 179 144
Cr. = final concentration, mg./100 cc.: u = adsorption, rng./gram. J
T.4BLE
Sample Weight. hlg. 750 500 350 200 100
111.
EFFECT OF SAMPLE WEIGHT AND INITIAL CONCEPU'TRATION ON
Initial Concn. of HC1 608 P. P. h l . 912 P. P. M. 1216 P. P. .\I. Cr. u CF U CF U 0.19 0.94 6.98 27.3 45.5
97 143 180 199 173
0.94 9.95 30.7 55.1 74.0
143 193 205 206 200
52.9 35.2 59.3 86.6 105.4
a 6-hour contact time, room temperature, 120-cc. volume of solution.
184 204 211 205 185
816 P. P. bf. CF u 0:35 2.8 15.2 42.0
I'9h
264 385 460
AMBERLITEIR-4a
Initial Concn. of HlSOa 1224 P. P. M. 1632 P. P. CP u CF
...
2.3 13.1 46.7 84.5
0.81 8.7 34.4 84 124
282 365 435 420
CF = final concentration, mg./100 00.; u
=
M.
2040 P. P. M.
U
CF
U
254 361 426 450 426
3.6 25.4 66.8 123.5 164
314 418 454 452 420
adsorption, mg./grain.
.
INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1941
TABLEIV. FREUNDLICH ADSORPTIONCON ST ANTS^ ADSORBENT RESINS Expt. No.
Resin Type
DU-1-74
Metaphenylene diamine Metaphenylene diamine Amberlite IR-4 DS-1-92 Modified phenoljc DS-1-90 Modified phenolic DS-1-88 Modified Amberlite ES-18-34 Modified phenol-sulfone 0
Screen Grading
+ + + + +
-20 30 -50 GO -20 30 -20 40 -20 f 40 -20 f 40 -20 40
-HCl-k n 10.1 0.334 1 2 . 5 0.365 161.5 0.070 2 0 . 0 0.300 8 . 2 0.263 2 9 . 5 0.263 8 2 . 0 0.147
OF
ANION
F--HzSOP-
l o n 6 . 9 5 0.600 1 6 . 0 0.602 195.0 0.187 130.0 0.210 110.0 0.201 140.0 0.109
...
...
k and n obtained from plot of u (adsorption in grams/gram) against c
(residual concentration in mg./100 00.).
TABLEV. FREUNDLICH ADSORPTION CONSTANTS OF CATION EXCHANGERS (CALCIUM-SODIUM EXCHANGE)" Material Greensand (commercial) Amberlite IR-1 Modified phenol-HCHO resin Carbonaceous zeoliteb I Carbonaceous zeoliteb I1 Carbonaceous zeoliteb I11 Carbonaceous zeoliteb I V Gel zeolite (commercial) Lignin-HCHO resin Modified lignin-HCHO resin
IC
n
0.13 119.0 118 51 34 30 1.5 18.0
1.260 0.000 0.007 0.173 0.202 0.186 0.860 0.324 Indeterminate 0.072
0.0
72.0
0 CaCb solation used; concentration, 187-467-p p. m. as CaCOs. 6-hour contact: 200 mg. exchanger, 100 cc. CaCln solution; soap titrati:n analytical method. b Carbonaceous zeolites used were commercial products proposed for cation-exchanqer purposes. Such products are presumably sulfonated organic materials, based on coal, lignite, eta.
1273
culated values on both anion and cation exchangers. The anion exchangers are grouped into pairs showing good agreement and poor agreement between the two values. The capacities of the cation exchangers were calculated to a volume basis, from a knowledge of the apparent wet densities of the exchangers. The number of cases in which good agreement obtains between the calculated and observed capacities outnumbers the instances of poor agreement. The results may be taken as evidence that the concept on which the calculations are based was fundamentally sound. The poor agreement is, with but one exception, due to a low column-exchange value. These cases may be due to premature break-through, produced by channeling in the bed. On the other hand, Wilson's theory demands a nondiffuse front proceeding down the column. The large difference between the calculated and observed break-through capacity values in the case of the carbonaceous zeolites was attributed to a diffuse front, in view of other studies which indicated a slow leakage beyond the break-through when the carbonaceous zeolites were used; the synthetic resin exchangers exhibited a sharp breakthrough and a rapid rise in the concentration of the effluent to the initial value (11).
~
+
METHOD.A 200-mg. sample, of -20 40 mesh grading, was used; 120 cc. of a solution of the acid were placed in contact, and the mixture was stirred for 6 hours. Similar studies on the cation exchanger led to the adoption of 100 cc. of a calcium chloride solution, varied from 187 to 467 p. p. m. as calcium carbonate, placed in contact for 6 hours.
RESIDUAL CONCENTRATION.
Adsorption Isotherms and Column Exchange Values The various resins were placed in exchange columns and the adsorptive capacity determined as described in a previous paper (18). The data are summarized in Table VI. The capacity listed is total capacity-i. e., the capacity obtained with the fully regenerated resin. Practical exchange capacities are, in general, much smaller in magnitude. This difference will be discussed later. The total exchange capacity was calculated from the Freundlich adsorption isotherms obtained on the various resins, a t concentrations of solute corresponding to those employed in the column experiments. The results were then compared with the exchange capacities actually observed. Table VI1 lists a comparison of observed and cal-
ACID//OOcc.
FIGURE4. EFFECTOF PARTICLE SIZE ON ADSORPTION OF HYDROCHLORIC ACID BY AMBERLITE IR-4 Screen grading8 (reading from top to bottom) 50/60, 40/50, 30/40, 20/30; the 60/70 and 70/100 cuts were identical with the 50/60. Freundlich isotherm constants were as follows: Grading 20/30 30/40 40/50 50/60 B 161.5 167.5 175 le8 n 0.07 0.083 0.085 0.114
Freundlich Adsorption Isotherm Constants of Resins Tables IV and V contain values of the Freundlich adsorption isotherm constants for several anion and cation exchangers, respectively. A wide variety of resins was examined, and the Freundlich isotherm fits well in all cases. While two arbitrary constants k and n are characteristic of each resin, it is conceivable that sufficient data would permit a classification of exchange adsorbents on the basis of numerical constants. Those resins with a low value of n are preferable in practical application since the adsorption is independent of concentration of adsorbed ion. The value of k is roughly indicative of probable capacity to be expected in practice. Figure 6 illustrates the variation in adsorptive capacity exhibited by several cation-exchange materials.
my
The adsorption isotherm technique outlined above has been found useful in the rapid preliminary evaluation of many new resins. As previously mentioned, the method is not to be considered a substitute for column-exchange studies. A full evaluation of a promising material must eventually involve investigation of regenerant ratios, head losses, rates of exchange, etc., which can be determined only in the customary fashion. However, the adsorption isotherm method has been found useful for a rapid survey of several kinds of exchangers.
TABLE VI.
TOTAL EXCHANGE CAPACITIES OF ANIONADSORBENTS (COLUMN STUDIES, 9 )
Expt. No. Type Resin DU-217 DU-217A DU-222 DU-222A DU-128 DU-128A DU-159 Amberlite IR-4 DU-185 Amberlite IR-4 Modified phenolic DS-190 DS-192 Modified phenolic DU-207A Modified phenolic Modified phenolic DU-207 DS-188 Modified phenolic DU-216 Modified phenolic Leakage of anion. b Another sample. Q
I= I1
IIb 111 IV IV
Soreen Acid P. P. M. Adsorption, Grading Used Acid Mg./G. -40 50 490 20.6 529 llG.6 -40 4-50 30 490 -20 34.3 30 529 -20 94.0 40 613 192.0 -20 40 449 -20 220.0 40 393.0 -20 5ee 368.0 -20 493 40 40 483 -20 45.0 45.5 -20 40 483 490 67.0 -20 40 490 33.0 40 -20 490 74.2 40 -20 529 40 -20 204.0
+ + + + + ++ ++ + +++
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
1274
The chromatographic banding concept, obvious as it may appear, does not seem to have been developed by workers in the base-exchange field. The capacities determined in the columns and calculated from the adsorption isotherms are total capacities, based upon the assumption that a single chromatogram is being produced as the solution passes progressively down through the column of fully regenerated
TABLE VII. COMPARISON OF ADSORPTION-ISOTHERM (CALCU-
.
LATED) AND EXCHANGE-COLUMN (OBSERVED) CAPACITIES
Expt. No
F R E U N D L I C H ISOTHERM CONSTANTS
Grading
k n
20/30 195 0.187
30/40 250 0.140
40/50 275 0.177
adsorbent. I n actual commercial practice the “usable” capacity, or capacity obtained with a fixed quantity of regenerant (which is, however, insufficient to produce complete regeneration), is important. If the regeneration is considered as the superposition of one chromatogram on another, it is conceivable that a suitable mathematical analysis should permit the calculation of exchange capacity a t any arbitrarily chosen regenerant ratio. Studies are in progress on this subject and will be reported a t a later date. The analysis of the problem indicates that it is much more complex than the simple chromatogram produced on a fresh adsorbent, and adsorption isotherms must be determined on resins in contact with a mixture of the exchanging and regenerant ions.
Chemical Aspects of Adsorption by Ion-Exchange Resins Bhatnagar, Kapur, and Puri (4) noted that a metaphenylene diamine resin adsorbed inorganic acids preferentially in the order sulfuric > nitric > hydrochloric. Column studies on Amberlite IR-4 indicated that the exchange capacities for phosphoric, sulfuric, and hydrochloric acids are in that order, as follows: Adsorptive Capacity As CaCOs, Milligrams Millcquivalents grains/cu. ft. acid/cc. acid/cc. 30,000 50.2 0.688 112.1 2.29 50,000 6.72 98,000 220.0 7
Acid HCI
&SOL
Hap01
Concentration,
P. P. M. 400 500 1500
The adsorption appears to be about 1:3:10 on an equivalent basis and 1:2:3 on a molar basis. The latter ratio suggests adsorption as whole molecules, with free acidic valences on the exhausted resin available for cation exchange. The adsorption of acids is also preferential, as shown by Table VIII. The data are the result of analyses conducted on sections of a column treated with a mixture of hydrochloric and sulfuric acids until hydrochloric acid appeared in the effluent. The preferential adsorption of sulfuric acid is strikingly evident and followed the chromatographic banding in the column. Table I X indicates a similar preferential adsorption of copper over zinc by the cation-exchange resin, Amberlite IR-1, although the separation of the bands is not quite so sharp. Synthetic resin ion-exchange adsorbents should exhibit preferential ion adsorption similar to those observed by Schwab (13, 14, 16) with inorganic ions on activated alumina, and the many similar observations with both colored and colorless organic substances on various common adsorbents (9,dO). No observations appear to have been made
p. p: M. Capacity. M d G . Acid Obsvd. Calcd.
34.3
37.0
DU-138 DU-128A DU-159 DU-185 DU-207A ~u-2~1 DS-188 DU-216
04.0 192.0 220.0 393.0 368.0 67.0 33.0 74.2 204.0
92.0 226.0 220.0 420.0 410.0 65.0 22.8 82.0 211.0
DE-217 D U-2 17A DS-192 DS-190
Anion Exchangers (Poor Agreement) Phenylene diamine HC1 490 Phenvlene diamine HzSOi 529 hlodi’fied phenolic I1 HC1 483 Modified phenolic I HCI 483
20.6 116.6 45.5 45.0
52.0 178.0 65.0 22.7
RESIDUAL CONCENTRATION, mg /IOOcc.
ADSORPTION OF SULFURIC ACIDBY AMBERLITE IR-4
Acid Used
Resin T y p e
Anion Exchangers (Good Agreement) Phenylene diRmine (-20 30) 490 Phenylene diamine (-20 4- 30) 529 Amberlite IR-4 I 618 Arnberlite IR-4 I1 449 Amberlite IR-4 566 Arnberlite 1Ii-4 493 Modified phenolic I1 490 7 Modified phenolic I11 490 Modified phenol/c I V 490 IllodiEed phenolic I Y 529
DE-222 DU-222A
FIGURE5. EFFECTOF PARTICLE SIZE ON
Vol. 33, No. 10
+
Cation Exchangersa Obsvd. Capacity, Calculated Grains CaCOa/ Resin T y p e Cu. Ft. Grains/cu. ft. Mg./gram Phenol-HCHO resin 17,500 16,600 90 Amberlite IR-1 20,000 22,000 119 Modificd phenol-HCHO resin 17,000 22,000 118 Carbonaceoua zeolite I 15,900 22,010 51 Carbonaceous zeolite I11 12.480 1x.190 Rn ~. Carbonaceous zeolite I V 7;OOO s;sF;o i4.5 a 500 p. p. m. of CaClz solution (as CaCOa)
on chromatograms on resinous ion-exchange adsorbents, although Flood (6) suggested zeolites as chromatographic adsorbents. The multiplicity of synthetic resin types appears to offer unique opportunities in colloidal research since the adsorbent may now for the first time be synthesized with certain active groups designed to accomplish a particular type of preferential adsorption.
Adsorption or Chemical Reaction Throughout this paper the exchange phenomenon has been referred to as an adsorption process. This term has been employed as a convenient designation of the over-all effects
TABLE VIII. PREFERE~TIAL ADSORPTION OF ACIDSBY AMBERLITE IR-4= Section No. 1 2 3 4 5 6 7 8
% c1
%S 11.64 11.59 11.59 11.36 Sample lost 3.20 0.00 0.00
0.00 0.00
0.00 0.00 1.17 12.32 18.31 13.00
Color Orange Orange Orange Orange Orange Bands overlap Brown Brown
a Solution (73 p. p. m. HC1 400 p. p. m. H B O d fed t o column, filled with -20 +40 Amberlite IR-4 unkil chloride ap eared in filtrate. Column cut into sections, approximately equal in lengt%. Resin dried in air a n d analyzed. Analysis on moisture-free basis.
ADSORPTION OF CATIONS BY AMBERTABLE IX. PREFERENTIAL LITE
Section No.
IR-1“
Vol. of Section, C c . 4.1 4.3 4.0 4.0 4.0 4.0 6.0 5.5 2,5
% cu
% Zn
6.71 5.88 5.69 5.20 4.45 3.42 1.38 0.26 0.06
3.03 3.14 3.19 3.23 3.81 4.70 6.18 6.00 2.84
p. m. ZnSOr. both a s CaCOd d. Solution 500 p p. m. CUSOPand 500 flowed througL oolimn of resin in sodium Firm until zinc first appeared In filtrate. Column cut into sections, resin dried in air and analyzed f o r copper and zinc. Analysis on moisture-free basis
INDUSTRIAL AND ENG INEERING CHEMISTRY
October, 1941
1275
(16) Schwarts, M. C., Edwards, W. R., Jr., and Boudreaux, Grace, IND. ENQ.CHEM.,32, 1462 (1940). (17) Sheen, R. T., and Kahler, H. L., IND.ENQ. CHEM.,ANAL.ED., 8, 127 (1935); Kahler, H. L., Ibid., 12, 266 (1940). (18) Tsmett, M., Ber. deut. botan. Ges., 24, 384 (1906). (19) Wilson, J. N., J. Am. Chem. SOC.,62, 1583 (1940). (20) Zechmeister, L., and Cholnoky, L. V., “Die chromatogi-aphische Adsorptionsmethode”, Berlin, Julius Springer, 1937.
r s?i
\
2 IO u
s
67
E
z, F h 0
PREBENTID before the Division of Colloid Chemistry at the 10lst Meeting of the American Chemical Society, St. Louis, Mo.
B T
IO 100 RESIDUAL CONCENTRATION- my CaCO3 / 1 0 0 ~ ~ .
FIGURB6. ADSORPTION OF CALCIUM BY CATIONEXCHANCP~ ADSORBEKTS
Iodine Number of Expressed Almond Oil W. A. BUSH AND E. A. LASHER 3135 East 26th Street, Los Amgeles, Calif.
FREUNDLICH ISOTH~RM CONSTANTSO
k n
IR-1
CI
CII
GI,
GR
119 0.011
0.142 1.506
17.90 0.362
16.14 0.365
0.133 1.260
- -
a IR-I = Amberlite IR-1’ CI carbonaceous exchanger I; CII = carbonaoeoua exchaiger 11; GZ gel zeolite: G R = greensand.
observed. Certainly in the case of the cation exchangers, and probably in the case of the anion exchangers, the primary process must be chemical reaction, but this is so masked by diffusion and reaction velocity factors that the practical equilibrium values obtained simulate adsorption values. Fundamental studies have been initiated to shed more light on the variables involved in ion exchange by synthetic resins.
Summary Synthetic resin cation and anion exchangers exhibit typical Freundlich adsorption isotherms when placed in contact with solutions of acids and salts. The adsorption which occurs in exchange columns may be considered as a species of chromatographic adsorption, and the break-through capacity may be calculated from the adsorption isotherm. Synthetic resins show preferential adsorption phenomena which is accompanied in some cases by visible chromatographic banding.
Literature Cited (1) Adams, B. A,, and Holmes, E. L., J. SOC.Chem. Ind., 54, 1-6T (1935); Brit. Patents 450,308-9 (June 13, 1936), 474,361 (Nov. 25, 1937) : French Patents 796,796-7 (April 25, 1936) : U. S. Patents 2,104,501 (Jan. 4, 1938), 2,151,883 (March 28, 1938), 2,191,853 (Feb. 27, 1940). (2) Akeroyd, E. I:, and Broughton, G. J., J . Phys. Chem., 42, 343 (1938). (3) Bhatnagar, S. S., Kapur, A. N., and Bhatnagar, M. S., J. Indian Chem. SOC.,16, 249, 261 (1939). (4) Bhatnagar, 9. S., Kapur, A. N., and Puri, M. L., Ibid., 13, 679 (1936); 17, 381 (1940). (5) Broughton, G., and Lee, Y. N., J. Phys. Chem., 43, 737 (1939). (6) Flood, H., Tids. Kjemi Bergwesen, 17, 178 (1937). (7) Griessbach, R., “Uber die Herstellung und Andwendung neuer Austauschadsorbienten, inbesondere aut Harsbasis”, Berlin, Verlag Chemie, 1939. (8) I. G. Farbenindustrie, Akt.-Ges., French Patent 820,969 (Nov. 24, 1937): Brit. Patent 489,173 (July 20, 1938). (9) Koshara, W., Chem.-Ztg., 61, 185 (1937). (lo) Langelier, W.F., J . Am. Water Works Assoc., 32, 279 (1940). (11) Myers, R. J., and Eastes, J. W., IND. ENQ. CHEM.,33, 1203 (1941). (12) Myers, R. J., Eastes, J. W., and Myers, F. J., Ibid., 33, 697 I1 941 ). .----I.
(13) Schwab, G. M., and Dottler, G., Angew. Chem., 50, 691 (1937); 51. .-, 709 .. (1938). . ~. .~ , (14) Schwab, G. M., and Ghosh, A. N., Ibid., 52, 666 (1939); 53, 39 (1940). (16) Schwab, G . M., and Jockers, K., Naturwissenschuften, 25, 44 (1937); Angew. Chem., 50, 546 (1937).
E
XPRESSED almond oil is the fixed oil obtained from the kernels of cultural varieties of Amygdalus communis (Linne). According to Jamieson (1) the bulk of the oil of commerce is expressed from bitter almonds. There is apparently little difference between the oils from the bitter and sweet varieties of kernels. The iodine number is reported by Jamieson (1) as 95 to 103. The Pharmacopoeia of the United States (3) gives the iodine number (Hanus) as not less than 93 and not more than 100. The only reference we have found to an almond oil with an iodine number above 100 is that of Nilov (d), who cites variation from 63.13 to 113.68 in the case of oil of sweet almonds. During the summer of 1939 one of us supervised the pressing and Gltration of about 2500 kg. of oil from almond kernels of the California crop of 1938. The kernels were collected from various parts of the state and represented more than two varieties of sweet almonds; no bitter almonds were present. Subjected to some of the usual tests for purity, the oil was found to have the following values:
The specific gravity by a very small margin and the iodine number by a rather wide divergence were outside the limits adopted by the Pharmacopoeial Convention. During March, 1941, we supervised the pressing of another lot of sweet almond kernels from several local sources (California), the operation producing 10,850 kg. of oil. I n the early stages of the operation iodine numbers were determined, and it became clear that the oil expressed from the assortment of kernels was again beyond the prescribed limits. Samples of the various cultural varieties of kernels were then expressed by hand, using a laboratory screw press. The oils obtained in this manner were tested in the usual way, and the results are tabulated below: Cultural Variety
Drake Ne Plus Nonpareil Texas
S p Gr.. SaponificaIodine No. Rcfraotive (Hanus) Index, 20’ C. 25 /25’ C. ticn No.
102.0 105.7 102.2
104.6
1.47246 1.47‘296 1.41246 1.47279
0.9138 0.9148 0 9138 0.9142
194.8 196.6 196.6 196.0
Acid
No. 0.42 0.29 0.19 0.16
Literature Cited (1) Jamieson, G. S., “Vegetable Fats &. Oils”, p. 32, New York, Chemical Catalog Co., 1932. (2) Nilov, V. I., Bull. Applied Botany, Genetics, Plant Breeding (U. S. 8. R.),A, No. 1 1 , 2 1 4 0 (1934). (3) Pharmacopoeia of the U. S. A,, 11th Decennial Revision, Easton, Penna., Mack Printing Co., 1936.
