ANALYTICAL CHEMISTRY
460 Table 11.
Effect of Various Anions upon Determination of Nickel
Anion Present Acetaten Chloride Sulfate Nitrate Perchlorate Tartratea Sulfosalicylate" 0 Small amount of
Anion
Nickel Taken
Weight of Precipitate
Sickel Found
Grams
Gram
Gram
Gram
.\lo.
4 5 0 0265 0.5 0.0229 1.0 0.0246 0.2 0.0266 0.2 0.0264 8.0 0.0238 5.7 0,0239 chloride present.
0 1554 0,1346 0.1440 0 1497 0.1531 0,1389 0,1400
0 0266 0,0230 0,0246 0.0236 0.0262 0.0237 0,023!4
+0.1 fO.l 0.0 +O.l -0.2 -0.1 0.0
Error
Table 111. Determination of Nickel in the Presence of Various Cations Cation Present
Cation
Nickel Taken
Weight of Precipitate
Sickel Found
Gram
Gram
Gram
Gram
Mg.
0.1386 0.1368 0 1381 0.1351
0 023i
0.0234 0.0236 0.0231
+0.1 0 0 0.0 0 0
0.1375
0.0233
0 0
0.1491
0.0235
0.0
0,1291 0,1301 0,1362 0,1373 0.14OY 0.1363 0.1226 0.1474
0.0221 0.0222 0,0233 0,0235 0,0241 0.0233 0.0210 0,0252
f0.1 +O.l 0.0 4-0.1 -0.1 0.0 0.0 0.0
0.0236 Cranyl 0.55 0.0234 Uranyl 0 23 Manganous 0.50 0 0236 hfaneanous 0.10 0.0231 Sodi;m 1 Potassium} 0.lOeacli 0.0235 Lithium J Barium 1 Calcium O.lOeac1i 0.02.55 Strontium] Magnesium 0.20eacli 0,0220 Cadmium Antimonite" 0.14 0,0221 Aluminumb 0.20 0.0233 Arsenite 0.34 0.0234 Beryllium 0.1 0,0242 Beryllium 0.3 0.0233 Zinc 0.1 0,0210 1. o 0,0252 Zinc a Complexed with 0 . 2 gram of tartrate h Complexed with 1 . 2 grams of tartrate.
}
Error
not precipit,ate below a p H of 5.7 ( l l ) ,the cornplexing agent is not necessary when the determinat,ion is conducted in the manner suggested. The precipitate from determination 11 was decomposed viith nitric acid and ignited to the oside. Spectrographic analysis revealed the presence of less than 100 p.p.m. of beryllium, indicating a successful separation. The data from these srparations are shown in Table 111. Copper yields a brownish green color with niosime, whercw
cdbalt gives a brown cjlor and is coprecipitated with nickel; this is in agreement with t.he findings of other workers ( 6 ) . A method for the satisfactory quantitative separatim of nickel from iron was not found. The difficulty lay in finding a complexing agent for the ferric ir~3n. The pissibility of using tartrate and citrate was exhaustively investigated. However, t,hese anims are known to reduce iron t 3 the ferrous state (9) which forms a very stable complex with nioxime and incomplete precipitation of the nickel results. Sioxime will als, reduce ferric to ferrous iron. Ferric sulf3,salicylate complex inhibits the precipitatim of the nickel ni ,xime and postprecipitation occurs as much as 24 hmra after filtratim. Fluoride, phosphate, and pyrophosphate precipitate ferric iron whereas dextrose, glycerol, salicylate, D-mannitol, and thiocyanate do not prevent hydrous ferric oxide from precipitating under the conditions of the recommended procedure. Ferrocyanide was ruled out, because nickel ferrocyanide is insoluble. 2,2'-Bipyridine csmpleses nickel as well as ferrous iron ( 7 ) and nickel nioxinirs is n-t precipitated in its presence. LITERATURE CITED
(1) Banks, C. V., A1.S. thesis, Iowa State College, .Anies, Iowa, 1944.
(2) Diehl, H., "dpplicatioti of the Dioximes t o Analytical Chemistry$" Columbus. Ohio, G. Frederick Smith Chemical Co.,
1940 (8) Feigl, F.,"Qualitative dnslyse mit Hilfe von Ttlpfelreaktionen," p. 73, Leipsig, Akademische T'erlagsgesellschaft, 1931.
Griffing, M.,Ph.D. thesis, Purdue University, Lafayette, Ind., 1944. (5) Hach, C. C.. Banks, C. V., and Diehl, H., unpublished work. (6) Johnson, W.C., and Simmons, M.,Analyst, 71, 554 (1946). (7) Sfoss, hf. L., with Mellon, M .G., I K D . EKo. C H E M . , AN.4L. E D . , 14,862 (1942). . (8) Rauh, E. G., Smith. G. F., Banks, C. V., and Diehl, H., J . Org. Chem., 10, 199 (1945) (9) Schoras, J., Ber., 3, 11 (1870). (10) Wallach. O., .4nn., 437, 175 (1924). (11) Willard, H. H., and Diehl, H., "Advanced Quantitative Analysis," p. 45, New York, D.'Van Nostrand Co.,,1943. (4)
R E C E I V EJune D 6, 194i. Presented in part a t the 15th RIidwest Regional O C I E T Y , Kansas City, Afo. Much Of this Meeting, .&\IERICAS C H E ~ I I C ISL work was done under Contract S o . IT-7403 eng-82 with the N a n h a t t a n Project a t the Department of Clierni3try, 1on.a State College. Contribution 16 o i tlic In-titiit? for . i t o l n i r Rpsenrrh, Iowa State College, .$mea, Iowa.
Determination of Asphaltenes, Oils, and Resins in Asphalt RETHEL L. IIUBB-IKD ~ V I- wattlr circulating from a ihermost at i d l y writ i,ol bath of large], capaci T h e nit, r c ur?-- s t' a 1 paddlc stirrer, H , is operated t>)-an osrillating motor, G, of thv th-pc comnionly used on nioFigure 1. Adapter for tor cars t o operate the Removing Solvent n.indshicild wiper. T h e liquid trap, K , in t h r solvent-return line aids in observing tht: color of the extract and retaining thcl fetv particles of alumina which may be washed out of the estraction crucible. Reagents. %-Pentane, C . P . grade. Different lots of a petroleum fraction of n-pentane had properties within the following limits:
G H. I J K
Osc!llating vocuum molar Mercury-seoled stirrer Inlet for flushing gas Extraction chamber w i t h crucible L i q u i d trao
. -
in
ploce
i
-
Density, d:' Refractive index, n y Boiling point a t 760 mni., C.
0.6255 to 0.6262 1.35752 to 1.35758 36.10 t o 36.15
Benzene, c.P. grade. Anhydrous methanol, C.P. grade. Anhydrous aluminum oxide, technical grade, screenrJd to pass a 100-hesh per inch sieve and be retained upon a 200-mesh per
SCOlE
3
0
3
6
9
I2
Centimeters
Figure 2. Constan t-Temperature Extraction ipparatus
inch hitw. The aluniina is hrated for 2 hours at 700" C. (1292" F . ) and caoled in a desiccator before being med. Preparation of Asphalt Sample. A sample containing 1.23 to 1.5 grams of asphalt (the smaller sample is used for asphalts c-ontaining unusually large proportions of rrsins or asphaltenes) is weighed accurately into a 100-ml. oil centrifuge tube. The tube is warmed t o soften the asphalt, x1-hic.h is then distrihuted evenly about the lower part of the tube. Determination of Asphaltenes. Forty milliliters of n-pentane per gram of asphalt are added to the sample in the centrifuge tube. The sample is dispersed by hand with a scre\v-type stirring rod. The tube is then supported in a water bath a t 15.6' C. (60" F.) and the sample stirred by rotating the rod at approsimatel? 2600 r.p.m. for 10 minutes. T h e stirring rod is removed, and t h r tuhe is: stoppered and allowed to stand approximately 12 hours or overnight in darkness or in subdued light. After standing the required time, the tube and its contents are again placed in the constant-temperature bath (at 15.6" C.) for 20 minutes. .it, the end of this time, the sample is stirred for 10 minutes in the manner described above and then centrifuged for 5 minutes a t a relative centrifugal force approximately 975 times gravity. The clrar pentane solution is decanted into a 300-ml. boiling
'
ANALYTICAL CHEMISTRY
462 fla,k and the approximate volume of pentane-insoluble I esidue i- noted. Twenty-five milliliters of pentane per milliliter of reiidue are added; the mixture is stirred for 10 minutes a t 1S.6' C., then centrifuged for 5 minutes in the manner previously clrhcribed. This washing process is repeated three times (a total of four washings); the same volume of pentane is used each time. The pentane washings are added t o the original pentane extract in the 300-ml. boiling flask. The pentane-insoluble asphaltene fraction in the centrifuge tube is dissolved in benzene and filtered through filter paper 36 34
+ Y z $
30
L w
d 26
F
The determination of the asphaltene, oil, and resin fractions can be completed in one 8-hour day after the sample has been dispersed in pentane and allowed to stand overnight.
0
4 U v
22 2 Y
A E
3
9
C D
18
L
Y)
F
Irma. Arh
Smockover, A r k urbono, Ark
EXPERIMENTAL RESULTS
Kern River, Colif Pondam, Man1 G r a i Creek, wyo
14
"16
20
24
28
Figure 3.
32
36 4 0 4 4 4 8 52 56 60 6 4 6 8 ASPHALT FROM CRUDE O I L , PERCENl
the boiling flask, and the extract is distilled to approximately 25 ml. of liquid. The concentrated oil extract is filtered through filter paper, dried, and weighed as described for the asphaltene fraction. (Occasionally the oil fractions from certain asphalts, particularly those having penetrations over 200 a t 25 O C., are partially volatilized by the usual method of drying. These more volatile oils are dried a t atmospheric rather than a t reduced pressure.) Determination of Resins. The Gooch crucible containing the mixture of resins and alumina is removed from the extraction chamber and mounted on a filter funnel, and the resins are eluted by alternately stirring the material with 10- to 20-ml. portions of a methanol-benzene solution (10 ml. of anhydrous methanol plus 90 ml. of benzene) and withdrawing the elutrient by means of suction. The resin extract is distilled to a small volume, centrifuged in a 100-ml. Goetz phosphorus tube t o remove fine particles of alumina, and filtered through filter paper into a weighed boiling flask. The resin extract is then distilled, dried, and weighed as described for the asphaltene fraction.
72
76
80
84
Asphaltene Content of Asphalts from Different Crude Oils
88
The yields of asphaltenes, oils, and resins from 117 asphalts prepared in the laboratory from 25 crude oils were determined by the method described above. The composition data for the 25 series of asphalts will be available in a forthcoming publication of the Bureau of Mines (81). The composition data for 47 asphalts prepared from 9 of the crude oils studied are shown graphically in Figures 3, 4, and 5 , which give the gields of each con-
8-/
lc7' /
I
J
1~
and, by means of the adapter, the extract is dried 25 minutes under reduced pressure in a n oven at 105' C. (221" F.) while the flushing gas is pawed through the flask. After drying, the flask is cooled in a vacuum desiccator, then flushed with air and weighed t o determine the yield of the asphaltene fraction. Determination of Oils. The combined pentane extract and washings from the extraction of the original sample are distilled on a water bath to remove most of the Dentane solvent. (If this extract l 1 1 I is allowed to stanb. for an hour or' longer before "I! 20 J4 28 32 36 a0 4 4 4 8 52 5 6 J O 6 4 6 8 7; i 0 8 4 d8 $2 26 Id0 further treatment, the air in the flask is displaced with ASPHALT FROM CRUDE O I L , PERCENT flushing gas, and the flask is stoppered.) The concenFigure 4. Oil Content of Asphalts from Different Crude Oils trated extract is evaporated to approximately 5 ml. and poured evenly over 25 grams of anhydrous alumina .n a Gooch crucible. Three- t o 5-ml. portions r of pentane are used to wash out the flask and transfer the pentane, I zoluble material to the alumina. This washing is continued until 46 Curve Source O f Crud8 011 the bottom of the crucible becomes slightly moistened nrith A Irma, brh solvent. When properly done, the upper portion of the column 8 Smockover, Ark C Urbono, Arh of alumina is dark and the lower portion is colorless, 42 D Kern River, Colif The crucible is placed in the extraction chamber of the apparaE Pondera, Moot t u s shown in Figure 2, and the discolored portion of the mixture js dried to a powder by stirring it gently in a stream of the flushL 38 ing gas. n.Pentane, which has been dried bv passing it through a column of anhydrous alumina, is placed in boiling flask A (Figure 2). The flushing gas is adjusted to bubble slov,ly s4 through the solvent, which is heated to boiling by a hot-water bath. By adjusting stopcock E, n-pentane, a t 15.6' C. from the cooling coil, is added slowly to moisten the sample; the flow of 2 3o pentane is then regulated to keep the crucible one half to three iourths full of liquid. The initial percolate from the crucible should be colorless or only slightly yellow. If it is more distinctly 26 colored, the analysis is repeated with a smaller sample of asphalt. This significant color indicates that the petrolenes have been improperly dispersed over the alumina or there is insufficient 2216 i0 24 2 8 32 36 4 0 4h 4 6 5 2 56 60 64 $8 7h 76 80 84 /B alumina to adsorb the resins completely. If the first percolate ASPHALT F R O M CRUDE OIL, PERCENT indicates that the resins have been Droperlv adsorbed. the stirrer is started and the extraction contin;ed?or one hour. The extracFigure 5. Resin Content of Asphalts from Different tion chamber and return line are then washed with pentane into Crude Oils *
7h
.
E
V O L U M E 20, NO. 5, M A Y 1 9 4 8
463
31 ituent
plotted against yield of asphalt, from the crude oil for each These straight-run asphalts were prepared as tkscribed in previous publications (19, 20) by topping the crude o i l by distillation at' atmospheric pressure and removing the litxavy distillate or lubricating oil fractions a t decreased pressure. 'The penetrations of the asphalts in each of the series are given in J'igure 6. Thus (Figures 3, 4, 5 , and 6) a n 80-penetration asphalt Imrn Oregon Basin, Kyo., crude oil (Figure 6, G) yielded 20.5*% itsphaltenes (Figure 3, G), 46.0% oils (Figure 4, G), and 33.5% ixtsins (Figure 5 , G ) . For asphalts from the same crude oil, the yields of asphaltenes :tnd in most cases the yields of resins increased with decrease in yield or penetration of the asphalt. On the other hand, the yivlds of oils generally decreased with decrease in asphalt yield and penetration. These findings arc in general agreement ivit'h (lata presented by Hoiberg, Hougen, and Zapata ( 8 ) . From the graphs of the constit,uerit yields, as illustrated b?J'igures 3, 4, arid 5 , the composition of the lOO-penet,ration asphalt of each of the 25 series was estimated. Figure 7 shows a cvniparison of the estimated composition of thrse 100-penetra-
tion asphalts, arranged in the order of their increasing asphaltene content,. Characteristics of Fractions. The asphaltene fractions were black solids which intumesced and softened on heating. The oil fractions were viscous liquids at room temperature and ranged in color from light, yelloiv to light orange. The resin fractions of the asphalts were dark, reddish-bron-ri to bron-nish-black semisolids, which softened readily on Ileatirig. Some of the resins were slightly tacky at room temperaturc.
sci,icss of asphalts.
PRECISlON OF METHOD
The precision of the method based upon a total of 41 analyses of 16 asphalts is given in Table I. These results sholv that tjhe yields of oils and resins deviatrd approximately twice as much as the yields of asphaltenes. Little difficulty was experienced in obtaining conFistent yields of asphaltenes within these limits. ;1 comparison of the compositions of coating (air-blown) asphalts by this method and t)y a method developed by Strietcsr (22) is given in Table 11. The coating asphalts and their analyses by the Strieter method lvere furnished hy 0. G. Strieter of thv Sational Bureau of Standards. The average yields of the asphaltene, oil, and resin fractions by the Burrau of JIines method i'ierth 0.6cc highei, 1.9O; l o i ~ e i , and 1 . 2 7 highei, reTpectively, than the average >ields of the CorieipJnding fractions hv the Strieter method. The differences in the oil and resin yields by the two methods are attributed largely to the different adsorbent, used-namely, anhydrous alumina and fuller's eaith. DISCUSSIOR
16 20
24
28
32
36
40
44
4 7 %
56
A S P H A L T FROM CRUDE O I L
Figure 6.
60 6 4
68
72
76
80
a4
aa
92
96 io0
PERCENT
Penetration at 25" C. of Asphalts f r o m Different Crude
Oils
As there are no abrupt changes in the chalacteristics of the series of hvdrocarbons constituting asphalt, its separation into arbitrary gioups of constituent5 such as a>phaltenes, oils, and r e m s must he made under carefullv controlled expericonditions If ieproducihle arc to he obtained. In thc, method described, it is
ANALYTICAL CHEMISTRY
464 Table I.
part to unstable compounds in thcs u-ht,xarits s,)lvcsnt, which con~ ~ Ito dryIiess. ~ sistently yielded an oil-likr rr,si(iue u ~ ,,\raporation I t is essential to allow the initial asphalt-pentane dispersions to stand approximately 12 hours or overnight as directed in the method. The inimediate drtrrmination of the asphaltenes from srlvciral saniples reduced thvir yicilds liy aii awrage of 1 . 3 5 . If thr petrolene fractions 01' thrse samplw wcw alloned t o stand overnight, a dark, reddish-hrown prclcipitatcs collected on the side+ of the flask. This precipitate did not rcdiasolve by the addition of frrsh pentant', which indicates it should have been removtvi its B part of t h v asphaltme or pentanc-insoluhle fraction. Washiiig thfl asphaltcines four tinicis \\-it11 25 nil. of pentant, pvr iiiillilitrr of residuc as directed i l l the nitthod does not complettsly remove all the pentane-soluble niatciial, but the amount of ptsiitanc-soluble niatclrial removed by each additional washing aftw four is slight. Consequrntly, four washings are considered ad(,quate for comparing thr yitJlds of asphaltc~nrs.' Watrr must lie effectiwly reniovod from the pwtane, alumina, and (,xtraction apparatus, as it ticcreases the adsorption of wsim arid causrs the oil yields to be correspoiidingly high. F:sct,pt for the series of asphalt.
