Se pa rati0 n of Nonionic Surf ace-Ac tive Agents from Mixtures with Anionics by Batch ion Exchange MILTON J. ROSEN Department of Chemistry, Brooklyn College, Brooklyn 7 0, N. Y.
b Nonionic surface-active agents can be separated from mixtures with anionics b y a batch ion exchange method in which a solution o f the surfactant mixture i s stirred with a relatively small amount o f a strong anion exchange resin. The anionic material i s adsorbed firmly b y the resin, and i s removed together with it b y filtration; i t i s then washed free o f nonionic material with methanol. The nonionic material i s recovered in substantially quantitative yield from the filtrate and washings. Results with 14 binary nonionic-anionic mixtures are discussed. of surfactants often contain anionics admised with nonionics. Anionics react with high molecular weight amines t o produce waterinsoluble salts, a reaction which is the basis for numerous methods for the quantitative determination of anionics (1-6). Therefore, it seemed likely that anionic surfactants could be separated from mixtures containing nonionics by the use of anion exchange resins, which are essentially high molecular weight amines. Because certain anionics are sensitive to acid, the so-called “strong” anion exchange resins were used, rather than the “weak” anion exchange resins. To keep the procedure as simple as possible, a batch method was used instead of the conventional chromatographic column. A number of preliminary runs mere made with the same binary mixture of surfactants under varied conditions to determine the effect of such factors as solvent, reaction time, ratio of resin to surfactant, and mesh size of the resin. The results are given in Table I. The data indicate that both water and aqueous methanol niay be used as solvents for the exchange, although water gives better results in this case. However, even with aqueous methanol, the nonionic could be recovered with >98% purity. I n subsequent work, aqueous methanol was generally used in those cases where the surfactants were not clearly soluble in water. The data also indicate that a ratio of resin to surfactant sufficient to have an exchange capacity of no more than twice that required theoretically by the anionic present is sufficient for most purposes.
A 50% increase in the resin (run 5 us. 4) produced very little change in the quality of the product. Also, a 5-hour reaction time appeared to be adequate (run 4 us. 3) for most purposes. The efficiency of the separation was also dependent upon mesh size of the resin, the finer mesh material with its greater surface area giving better results (run 4 vs. 1). I n this respect, batch operation has a distinct advantage over column exchange, as in the latter very fine mesh material cannot be used because it markedly decreases the flow rate and thereby increases the time needed to process a given volume of solution.
IXTURES
PROCEDURE
A synthetic binary mixture containing 1 to 1.5 grams of nonionic plus 1 gram of anionic surfactant was dissolved in 50 ml. of either water or 1 to 1 aqueous methanol; then 10 grams of Dowex 1-X2 (Dom Chemical Co., 200 to 400 mesh) strong anion exchange resin was added, and the mixture was stirred a t room temperature for 5 hours. The mixture mas then filtered, and the resin washed a few times to remove any adhering nonionic material. Washing the resin with water did not effect complete removal of the nonionic from the resin, even after several washings by suspension. Two to three washings by suspension with methanol, however, gave substantially complete removal of the nonionic. I n order to remove the nonionic material from the inorganic chloride which is produced in the reaction of the metal salt of the anionic with the quaternary ammonium chloride anion exchange
Table 1.
resin, the filtrate and washings containing the nonionic were evaporated to dryness on the steam bath and in the oven and the residue was extracted a few times with acetone. After removal of the acetone on the steam bath and in the oven a t 110” C., the residue was weighed, its index of refraction measured, and its ash content determined by ignition in the presence of nitric and sulfuric acids. RESULTS
The results obtained by the use of this procedure on 14 synthetic mixtures of anionics and nonionics are shown in Table 11. The anionics and nonionics used in these mixtures represent all the major types of surfactants available commercially, and many of the less usual commercial types. The yield of nonionic in almost all cases averaged 100&5%. Because the weighings mere done on a laboratory balance with a sensitivity of 0.01 gram, this is almost within the experimental error of the weighings. Occasionally, however, a much greater yield of nonionic was obtained (run 11, 114%; run 17, 125y0). Because the ash content in these cases was no higher than in other runs, it was assumed that this was due to the presence of nonionic material in the anionic surfactant, probably unconverted base material. This was also reflected by deviation of the refractive index of the product from the expected value. To test this hypothesis, an anionic material, Triton 770, which gave a very large yield of excess nonionic, was sub-
Recovery o f lgepal CA-710 from Mixtures with Ultrawet K“
Conditions Recovered Igepal* Solvent Time, ResinId Yield, Ash, (50 ml.). hours grams Mesh size % ’ n $6 % 5 10 108 1 HzO-CHPOH 40-60 1,4929 0.80 3 10 200-400 2 H20-CHaOH 107 1.4930 1.10 3 H,O-CH,OH 7 10 200-400 104 1.4912 0.33 105 1,4924 0.55 4 H~O-CH~OH 5 10 200-400 5 HzO-CH30H 5 15 106 200-400 1.4924 0.40 6 HzO 5 10 200-400 101 1.4907 0.03 1.4912 0.11 200-400 101 7 H20 3 10 1.5 grams of Igepal CA-710, 1gram of Ultrawet K. * Refractive index of Igepal CA-710 used in preparing the mixture, n2,, 1.4890; yo Ultrawet K = Yoash X 5 . Water-methano1 solvent, 1 t o 1. Strong anion exchange resin with low percentage of cross linkages; capacity, 1 It 0.2 meq. per wet gram. Run No.
VOL. 29, NO. 11, NOVEMBER 1957
1675
Table 11.
Recovery of Nonionics from Mixtures with Anionics
Nonionic Product Run NO.
8
Yield, Components and Structure Monamid 150D, diethanolaminecoconut fatty acid con- / densate UltrawetE, R SOJNa
3
+
9 10 11
+
G-672, glycerol sorbitan ester, Lathanol, Na lauryl sulfoacetate Sterox SK, RS(C2H40)zH, Sarkosyl XL100, Na lauroyl sarcosinate Ethofat 142/15, RCOO(CzH40).H,
+
+
12 13
Triton X200, S03Na Propylene glycol monoolzate Sulfonate OA5, Na sulfostearic acid Polyoxypropylene mannitol dioleate Polyfon T, N a lignin sulfonate
+
+
n
Ash,
yo
Obsd.
Theor.
97
1.4770
1,4732
0.15
104
1.4686
1.4690
0.05
104
1.4790
1 ,4770
0.40
114
1.4802
1.4732
0.05
105
1,4660
1.4581
0.12
89"
1.4697
1.4698
...
103
1.4911
1.4918
...
103
1.4828
1.4820
...
98
1,4530
1.4520
...
125
1.4710
1.4586
0.20
36
1.5055
...
0.20
97
1.4748
1,4740
...
105
1.4632
1.4631
...
103
1.4560
1.4550
94
1.4682
1.4672
%
14 15 16 17
carballylate Sterox CD, RCVOO(C~H~O)~H, Duponol WA, ROSO3Na Brii 30. RIOCJLLOH. Aerosol dT, sulfdsuc6inaie Renex 30, R(OC?Hd),OH, Triton
+
+ +
770, R@OC;Hi)iiO4hr
0
18
Triton 770, R
19
Span 20, sorbitan ester, Hyponate L, petroleum sulfonate Polyethylene glycol 400 monooleate, Stepanol &IS,ROS08Na Pluronic L62, polyoxyethyleneoxypropylene glycol Igepon AC, ?r a lauroyl isethionate G-1165, polyoxyethylene gAucoside
20
21 22
(OC2H4),S04Na
+
+
+
+
ester, Daxad 11, ( SOtNa a
Product not readily soluble in methanol.
jected by itself to the ion exchange procedure. The results (run 18, Table 11) showed that a considerable portion (36%) of the original material was nonionic. This accounted almost exactly for the extra 25Yc of nonionic material obtained in the previous run. The high index of refraction of the nonionic portion accounted for the large deviation in the refractive index of the product from run 17 and indicated the impurity to be unsulfated alkylphenouypolyethoxyethanol-Le., unconverted base material. The poor yield of nonionic in run 13 was found subsequently to be dup to incomplete removal of it from the resin during the washing procedure, because of the unusually low solubility of this particular nonionic in methanol. Run 10, in which a salt of a n acylated amino acid was separated successfully from a nonionic, indicates that the procedure can be used to separate carboxylic acids and their salts from nonionic materials. The elution of the anionic portion from its complex with the ion exchange resin and the separation of nonionics from cationics by batch ion exchange are under investigation at present. LITERATURE CITED
Epton, S. R., Trans. Faraday SOC. 44, 226 (1948). Klevens, H. B., ANAL.CHEM.2 2 , 1141 (1950). Kling, W., Puschel, F., Melliand Teztilber. 15, 21 (1934). Lampert, J. M., J. Colloid Sci. 2, 479 (1947). Van der Hoeve, J. A , Rec. trav. chim. 67,649 (1948). Wijga, P. W. O., Chem. Weekblad 45, 477 (1949). RECEIVED for review October 26. 1956. Accepted June 10, 1957. Meeting-inMiniature, N e w York Section, ACS, March 16, 1956.
Determination of Higher Aliphatic Aldehydes in Presence of Ketones and Fatty Acids L. D. METCALFE and A. A. SCHMITZ Research Division, Armour and Co., Chicago
b The ease with which aliphatic aldehydes are oxidized to fatty acids is the basis of a method for determining higher aliphatic aldehydes in the presence of ketones and fatty acids. The aldehyde is oxidized to fatty acid with a mixture of 370 hydrogen peroxide and standard sodium hydroxide. The amount of standard alkali used in the reaction is a measure 1676 *
ANALYTICAL CHEMISTRY
9, 111.
of the aldehyde.
Any free fatty acid in the aldehyde is titrated separately and a correction is provided.
I
of higher aliphatic aldehydes from fatty acids, it became necessary to determine the aldehydes in the presence of ketones and fatty acids. A number of analytical systems have been devised for deterN THE MANUFACTURE
mining aldehydes in the presence of ketones but none specifically for aliphatic aldehydes of higher molecular weight. Methods include use of bisuifite (Zl), dimethylhydrazine (W), hydroxylamine (6, 6 ) , paper chromatography (18, 19), and a series of oxidizing agents (1, 10, 14-16, $0,272). Blank and Finkelbeiner (2, 3) first proposed oxidation with alkaline hydrogen per-
