Wetting and Spreading Properties Oleic Acid-Sodium Carbonate Mixtures n. L. CUPPLES
.
Bureau of Entomology and Plant Quarantine,
U. S. Department of Agriculture, Washington, D. C.
Surface tensions, interfacial tensions, and spreading coefficients on a refined paraffin oil were determined for aqueous sodium carbonate-oleic acid mixtures containing 1.0, 0.3, and 0.1 per cent of oleic acid, and with a varying alkalifatty acid ratio. These mixtures are much less sensitive to variation of this ratio than are the comesponding sodium hydroxide-oleic acid mixtures.
of Aqueous Solutions
QT
HE first paper of this series' described
a convenient method for investigating the wetting. . properties of aqueous solutions, and preserrterl the results of such a study of aqueous sodium hydroxide-oleic acid mixtures. It was there shown that the wetting properties of these mixtures are dependent upon the alkali-fatty acid ratio, and that at moderately high concentrations a slight excess of the alkali will greatly decrease the wetting ponw, whereas at lower concentrations an excess of alkali is advantageous. Under these circumstances, therefore, a soap mixture containing the proper alhli-fatty acid ratio for maximum wetting properties at low concentrations will, a t higher concentrations, produce solutions having inferior wetting properties. MoreoTTer, in practical owrations the wetting properties may vary with the acidity or alkalinity of the water supply. These facts show that it may he difficult to aroid variations in tho wetting power of such mixtures, which may help to explain the difficulties sometimes eneonritered in obtaining reproclucihle resiilts in spraying nperations. Since it seemed probable that solotions of superior wetting properties might he obtained by conihining oleic acid with a different base, an investigation was made of oleic acid-sodium carbonate mixt.nres. The result,s of this investigation are present,ed here. ~
Experimental Procedure The experiiiiental procedure was identical with that used in studying the oleic rtcid;;sodiurn hydroxide mixtures except that with a few of the solutions it was found necessary to filter off the suspended solids hefnre measuring the surface and interfacial tensions. At the higher concentrations no difficulties were eiieountered when testing the unfiltered solutions, but at the concentration of 0.10 gram of oleic acid per 100 cc. of solution, and at the lower alkali-fatty acid ratios where considerable suspended solid is apparent in the solution, erratic results were ohtained in nieasurements of interfacial tensions. Filtration of such solutions through ordinary analytical filter paper removes the less finely dispersed solids but not the colloidally dispersed material. The surface tensions were found to he practically unchanged after filtration, but the interfacial tensions against oil were higher and reproducible. It. is believed that the lees finely dispersed solids in the imfiltered solutions in some way interfere with the measurement of the interfacial tensions without contributing to the actual wetting power of the solutions, and that a satisfactory ineasure of the wetting power may be obtained by first filtering off the more coarsely dispersed material. In these ineasiiremcnts the spreading coefficient, S, of a sortp solution over the standard oil is defined by the equation: S = TB - T A - T A B where T B = surface iension of oil (30.5 dyneslcm. a t 25" C.) Ti = surface tension of soap solution
TM
Shaded area indioates region of poriiive nprerding rooSeieiitr: ieierence liquid. rni"8li)l uii: tempereiure. 2 5 - c.
= interfarid t,ension
Discussion of Results
0.30; and 0.10 grant of oleic acid i x r 100 cc. Althoiigh the spreading coefficientsvary uvith t,he alkali~~fatty acid ratio, the variation is much less pr(moiincec1 than in the case of the sodiuiri hydroxide mixtures. This is ~mticularlyevident at the higher concentr a t ions. '
Table I and Figure 1 show how t,be wetting proprvtias ,-my with the alkali-fatty acid ratio for ?elutions containing 1.00, 1 IND.
ENa. Camsr.. 27, 1219 (19351
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VOL. 28, NO. 1
INDUSTHIAL AND ENGINEERlNG CHEMISTRY
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~ ~ _ _ _ _ ~
~
TABLE
0.75 0.85 0.95 1.04 1.05 1 25 1.50 2.00
25.5 25.6 25.4 25.5 25.6 25.8 26.2 27.1
4.00
28.4
3.00
27.6
~
1. VARIATIoN IN WETTINO PROPERTIES WITH SoDlUM CARBONATE+LElC ACIU RATIO
1.8
0.5 0.4 0.2 0.8 0.8 0.3 0.4 0.8 1.2
1-8.2
+4.4
+4.i
+4.8
0.70 0.90
1.w
f4.7 +4.4 +4.0
1.10 1.25 1.50 I .75
13.0
8.00 4.00
i-2.1
f0.9
26.2 25.4 25.6 25.3 25.2 25.4 26.5 28.4 28.3
5.3
S 5 3.1 1.7 1.2 1.1 1.5 2.1 1.6
0.0 +1.6
0.80
f1.Q
1.26 1.50 2.00
+:i 5 +4.1 f 4 0 i-2 5
1.00
3.00 4.00
25.0 25.2 25.2 25.1 25.1 27.3 27.6
13.8 10.7 7.4 4.5 8.5 2.6 2.6
-8.3 -5.4
-2.1
+0.# +1.9 10.6
f0.3
0 0
i-0 6
At the concentsation of 1.00 grain of oleic acid per 100 cc., 0.10 gram of oleie Reid per 100 cc. the sodium carbonate mixthe sodium carbonate mixtures have excellent wetting proptures are less sensitive to excess of the alkali than were the sodium hydrnaide mixtures, hut the difference i s not so proerties throughout the entire range studied-that is, with variation in the alkali-fatty acid ratio between 0.75 and 4.00. nouincecl. This is in marked contrast with the behavior, at the same As an alkali for use with oleic acid in the preparation of concentration, of sodium tiydroxideoleic acid mixtnres, in aqueous solutions having superior wetting properties, sodium which case a slieht excess of the alkali was found to he deleearbontite hiis some definite advantages over sodium Iiydroxide. At a given cooterious to the wetting properties, giving miscentratiim the wetting tures with n e g a t i v e properties of the carbonate mixtures are spreading coefficients rniucii less seusibive to on oil at all alkalivariations in t h e fatty acid ratios exalkali--fatt y acid ratio, ceeding 1.04. Also at the eonoeiiand t,hereforeit stiould tration of 0.20 grain beeasier to inaintaiiia of oleic acid per 100 co nsistciu t 1y h i g h cc. the sodium carvalue of the spreading coefiicient in the bonate mixtuses have escellent v e t t i n g preparation of thecarproperties over a vide bonnte solutions. In range of alkali-fatty using the carbonate d u t i o n s there sIpild acid ratios (from also be less a n c o n a h o u t 0.9 t o 2 . 0 ) , whereas in the case of t r o l l e d variation in the sodium hydroxirlc the wetting properties due to acidity or aIkamixtures the spreadl i n i t y of t h e water ing coefficients were negative at ratios exused in diluting the mixtures. ccedmg about 1.3. At the concentration of FARM PLANTFOR PBEPARINQ OIL P:.UUI~~IONS R ~ c n r v ~July o 9. 1935.
Non-Ferrous Research in Great Britain 0 PROPOSALS for an impoilant expansion in the work of the British Nan-Ferrous Metals Resesreh Assoeiaiion by the inauguration of a five-year plan of research are reveded in the recently issued fifteenth annual reportofthcassoeiation. Member firms and various trade organizations recommended, on request, over one hundred new subjects for research, covering a very wide field. The present mogmm includes some fifty i k m a grouped in the main divisions of melting and solidification; working of solid metals to finished shapes; heat treiLtmrrrt a n d annealing; mechanical and physicysical propcrties of metals; oxidation, corrosion, and protectioii of metals; and electrodrpo work on a number of other items fdling out sions, as for ~xaniplecapper-hnso bearing mctnls, is proposed. Nine n w rcsensehrn are to be hegun in 1935, including investigations on nrelbina and casting brnnse, on nickel d v w . and on
n block-grant of SSOOO annually. In addition, the gdvernment will give R further giant of S250 annually to match each further $250 annually rained by the indusiry up to n limit of €3000.
A further SI000 a year may also be earned on x modified basis, so tliiit, under the n m agreement, n maximum contribution by the stxte of S12.000 IL venr is Dossiblc. Tlir report iridic& that, &stantid proogress was mado during thc past year in the assoointion's existing program of researob. A number of firms are successfully using the clieap and simple method developed by the association for eliminating dissolved gases from melts of aluminum alloys. The effect, of additions to galvanizing hnths is being studied and a mport dealing with the
effect of addit,ions of aluminum has hecn issued ta member firms. Closely connected Kith tlic rescareh on g&vnnising, investigations on the propcrtirs of zinc coatings have led to the develop inent of n new test for galvanized coatings on wire, and have provided vrrluahlc information regarding the resistance of the ercep properties of Ipnd and lend R I I o ~ s , and the corrosion of these mntcrialr is a qucstion which is now being considered also. ReDoris hsvc heen issucd to mPmher firms on the dcterminatian of srnnll amounts of impurities i n aluminum and of bismuth in eoppcr by spceirographie methods. It is eaprcted that the investi&ion, vhich has been in progrcss for the last five pars, on the suibsbility of various tornarp and more complex alloys of nickel, eobelt, chromium, copper, iron, and aluminum for service at high temperatures will be completed during the year. [Trade and Engineering (London), Vol. 37, No. 858, August, 1935.1
