INDUSTRIAL AKD ENGINEERIXG CHE1IISTHI
J L S E , 193.5
-1method i h demibed for calculating the equilibrium vapor pressure curve and operating curve for the three-component >pteiiiin the regenerat’or. By means of these curves the number of theoretical plates required for regeneration map be found, or the mean driving force for the diffusional process. While the quantity of steam required for the regeneration depends greatly on the concentration of the sulfur dioxide in the feed, it cannot be materially reduced by increasing the height of the regenerat’or over eight or ten t’lieoretical plates. Diagrams are given by which the quantity of steam may be estimated for different absorption temperatures and concentrations of sulfur dioxide in the original dilute gas when the process is used for the recovery of the sulfur dioxide from such gases. For a solution 90 per cent saturated in respect to a 0.4 per cent gas a t 3.5’ C.. the quantity of steam required is approximately 4 pounds per pound of sulfur dioxide. when the regeneration is at 90” (’. The operation of a coluniii of the filled column type is described. It was found that the H.E.T. P. varies considerably with t.he composition of the feed to the column but the valueb of Koa for one vapor 7-elocity are approxiniately constant and over a limited range vary with the velocity. Further data on packing and other types of regenerators are being obtained and will he reported later. Nomenclature S = concn. of sulfur dioxide in soln., moles/100 moles water (,’ = concn. of ammonia in soln., moles/100 moles water I = mole fraction of sulfur dioxide in soln.
66.5
mole fraction of ammonia in soln. mole fraction of water in soln. mole fraction of sulfur dioxide in vapor phase mole fraction of ammonia in vapor phase mole fraction of n-atw in vapor phase
P, = T = J-
F = L = P =
rv
=
R =
H. E. T. P.= Koa =
empirical constants in equilihriurn vapor-pressure equntions partial pressure of romponent indicated hy subscript, mm. vapor prePsure of pure \rater. nini. abs. temp. moles of vapor per unit time moles of feed soln. per unit time moles of soln. leaving regenerator moles of product (pure sulfur dioxide) per unit time moles of waste per unit time moles of reflux per unit time height equivalent to one theoretical plate absorption coefficient, Ib./min./cu. ft. ,’mm. difference in vapor pressure
Literature Cited (1) Brown, Souders, and Nyland, ISD. ESG. CHEXI., 24, 522 (1932). ( 2 ) Clark and K r a s e , Ibid., 19, 205 (1927). ( 3 ) Johnstone, Ibid., 27, 587 (1935). ( 4 ) Shern-ood and Gilliland, Ibid., 26, 1093 (1934). RECEIVEDFebruary 4, 1935. Presented as part of the Symposium on I l k tillation held under t h e auspices of t h e Dirision of Industrial and Engineering Chemistry of t h e American Chemiral Society a t the Massarhusetts Institute of Technology, Cambridge, Mass.. December 28 and 29. 1934 This paper contains part of t h e results of a codperative research, Projert No. 34, with t h e Utilities Research Commission, In?., entitled “ A Study of Stack Gaees.” It is published by permission of the Director, University [ i f Illinois Engineering Experiment Station.
Dispersion of Metallic Soaps in Fatty Acids d
C. J. BONER Battciifeld Grease & Oil Corporation. Kansas Cit), 3fo.
EM
ETALLIC soaps may, according to the findings of numerous investigat’ors, be kept in solution or suspension by keeping the solution highly acid. Ruemele (7) states: “ILL the case 07 well-bodied oil varnishes, aluminum stearate of high acidity is recommended. Further in lacquer, clear lacquers are obtained only with aluminum stearate of low ash content.” Elm ( 2 ) makes the following statement: “Flocculation and coagulation cause some drier chemists to resort to the use of solubilizing agents, mostly of an acidic nature.” The following v-as noted in a trade bulletin (6): “Some difficulty has been experienced with solutions of cobalt and manganese driers. However, good results have been obtained by adding about 10 per cent of linseed oil fatty acids or 2 per cent of benzoic acid to the drier solution.” Gardner (3) in speaking of granulation in ready-mixed paints due to particles of metallic soaps sayi: “On the other hand, great quantities of free fatty acids or resin acids may prevent the formation of granules, in that they disperse them or hold them permanently in solution, thus preventing precipitation of the soaps.” +Ipprtrently only one cherniqt has experimented along the
line covered by this paper. Baldwin (1) dispersed a series of metallic soaps in oleic acid. No detail was given as to composition of the soaps. Correction was made for the free fatty acids in the soaps when freezing points were taken of the mixtures. From the freezing points, Baldwin concluded that colloidal dispersion and not true solution of the metallic soaps resulted.
Dispersion Experiments The following work was done entirely with commercial materials, eliminating as many factors as possible which might prevent accurate conclusions. I n choosing fatty acids, types were not taken from any strictly drying oils, so that they would be stable on prolonged heating. Therefore, the following acids were used : oleic, tallow, cottonseed, coconut, and abietic. The acids were saponified with potash and the soap was decomposed. After separation, the fatty acids were boiled with dilute mineral acids, washed thoroughly, and dried. Ash was taken on all acids as a check that they were free from soaps. This gave fatty acids of the following titer; oleic 11.01, tallow 36.07, cottonseed 35.10, coconut 22.63. The abietic acid was a commercial product and was checked only as to freedom from moisture and ash. I t had a melting point of 205” F. The soaps used were aluminum stearate, calcium stearate, magnesium stearate, lead naphthenate, and aluminum oleate. All commercial metallic soaps are a p t to contain the following impurities: moisture, inorganic salts, free fatty
ISDUSTRIkL -4ND ENGINEERISG CHETIISTRI-
666
TABLEI.
C03fPOSITIOS OF
Soap A1 stearate Castearate 31g stearate P b naphthennte .I1 oleate
-4s-Rereived Moisture 0 90 0.10 0 36 Trace Trace
LIETALLIC Tl-aterSoluhle Content 0 i5O 0 . 17 0.32 0 0i 0.28
SOAPS ( I S P E R CEST)
.ifter Washing and I)rq-ing Free fatty acids As11 10 87 11 76 .I1:02 10,41 13.08 CaO 9.68 1' 00 \IaO Not detd. 4 1 , 2 8 PbSOr 23, h
{ j:. t: (
sodium soap. 19.4ycfree fat.
a 0.20% b Also
u. v.)
;?'io,% r(
101, 2 7 . \ O . 6
were then held at 150" F. for n f ~ u ~ t h cl~eriod >r of 30 &iy- \\-lthout being tii.turbed, so th:it any lettllng of w:ip \voultl be evident in this period at this temperature. In order that osichtion of acids might not give ahnornid re*u!ts. pmillel port ions of the different acid3 Tvere heated and held t i - dewritletl in the Eoregoing. These particular acid were u-et1 f o r fl,eezing p(ji11t determination$. Even the fnttj icitls recovered fi,oni the tlifferent $naps were subjected to the ,same treatment liefore their freezing points ivere taken.
e:w
Mixtures used, with the resulting freezing poiut.. n i l t l \-iscosities, are shown in Table 11. Freezing points were taken in a Dewar tube. I n vien. of the fact that the free fatty acid acids (or free fat), oxides or liytlroxides of the metals, and content' of the soaps TT-ouldinfluence the freezing point, a other soaps. If the metallic soap is made by precipitation, corrected freezing point Jvas tleterniinetl. This vas acthe soap impurity n-ill probably he sodium or potassium soap. complished by an actual mixture of the extracted f'att>-acicls These impurities vary in different lots of metallic soap and from a mctallic soap with the solvent fatty acid>. The add to the difficulty of accurate results; therefore, as many proportion of the former was that in which the -oap iutroas possible of these variables were eliminated. duced these fatty acids-i. e.: the percentage of soaI) in a mixture times the - percentage of free TABLE11. MIXTVRES WITH RESVLTISG FREEZING POINTS ISD VISCOSITIES fatty acids ahon-n Cor. in Talde I. DifferTemFreezing Freezing J-iseiice i n f r e e z i n g perature, Pzint, Point, cosity Percentage Soap F a t t y Acid F. Result of Mixture F. ' F. Saybolt m i n t of this mixCoconut ... . .. .,.. 22.59 57 a t 122' F. ture antl that of 3 :4 '.ii stearate 150 235% (dissolved) 22.63 22:?2 70 a t 122' . . .. . . Cottonseed ... ... 35.10 83 a t 1 2 2 O the solvent fatty 0 . 4 4 A1 stearate l i b y o sepn. after 3 mo. 35 32 35:36 88 a t 122' acids gave a 0 . 9 2 C a stearate 150 N o after-sepn. 35.31 35.31 89 a t 122' 1 . 7 1 Ca stearate" 150 N o after-sepn. 35.80 89 a t 122' correction w h i c h 0 . 9 2 ;il oleate 150 N o after-sepn. 35.02 85'07 92 a t 1 2 2 O was applied to the 3 , 8 0 P b naphthenate 150 No aiter-sepn. 34.46 .. 92 a t 122' Tallov 150 c o r r e .< 11 o 11 d i n g . . .. , . .. 36,07 85 a t 1 2 2 O 0 9 5 ' ~ stearate a 150 S o after-sepn. 34.65 34.68 92 a t 122' freezing point of 150 2 . 2 2 l l g stearate S o after-sepn. 36.49 36.21 98 a t 122' the metallic soap ...... Oleic 150 11 00 103 a t 100' 1.60 .I1 stearate 150 i 53y0.djssolved 19 03 19' i 2 109 a t 100' dispersion. 2 . 3 5 C a stearate 150 0 . 33y0 dissolved 18 83 18.90 112 a t 100' 0 . 9 9 Ca stearatea 150 S o after-sepn. 17,64 124 a t 100; While t hi. n-ork 1 . 4 2 A1 oleate 150 No after-sepn. 13:& 120 a t 100 13.73 does not indicate 1 . 9 6 A1 stearate -4bietic 375 No fusion when held a t 37:' ... ... ..... 4 . 2 8 C a stearate 375 h'o complete fusion a t 375 ... ... that fatty acids are 3.81 M g stearate 375 Fused a t 280'; universal tlispersno sepn. when held a t 875' F 18.8 .... 207 11.80 P b naphthenate 375 Fused below- 280'; ing agents for no sepn. when held a t 375' 175 ,.... . . . Free from fatty acids m e t a 11i c -0a n s . further wnrk may 1-erify com~~iercial Moisture can be disposed of most readily and \\-as acresults. 1-ariations of proportions of metallic map< in fat'ty acids will probably show that an optimum exi complished after water extraction. Removing the moisture metallic soaps and fatty acids. mill influence the dispersion for some purposes as Jones The freezing points of dispersions show, n-ith two exceppoints out, ( 6 ) . Using the same experimental materials, it tions, no lowering; thus a collodial dispersion antl not a true is hoped later t o determine whether t,he addition of small solution is indicated. This finding TI-RS further verified by quantities will help dispersion. the Tyndall effect' shown by all the dispersions. The inorganic salts consist of t'hose left from fusion or precipitation. Since all the metallic soaps worked with were Literature Cited made by precipitation, we would have sodium sulfate, alumi(1) B a l d w i n , ;im.Paint V a r n i s h Mfrs. .\ssoc.., C'irc. 356 ' O c t . , 1929). num sulfate, lead acetate, etc. The first treatment of any (2) E l m , ISD. ESG. CHEM., 26, 386 (193.11. metallic soap was repeated extraction with wat'er in a Soxhlet (3) G a r d n e r , in -Alexander's "Colloid t filling them so that little air n-a3 included. These tiottles April 2 5 , 1935 ~~
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