(3) Heal, H. G., Can. J . Chem. 31, 91 (1952). (4) Heal, H. G.. Ibid., 37,979 (1959). (5) Hodgden, H. W., Ingols, R. S., AKAL. CHEM.26, 1224 (1954). (6) Hum, R., “Chemistry for Engineering
Students,” Charles Griffin, London, 1945. (7) Xauch, Isledovakl, Tr. N o s k . Tekstil. Inst. 13, 115 (1954). (8)Schumacher, J. C., “Perchlorates,
Their Properties, Manufacture and Uses,” ACS Monograph KO.146, Reinhold, New York, 1960. (9) Scott, W. W., “Standard Methods of Chemical Analysis,” 6th ed., Tan Nostrand, New York, 1962. (10) Sherman, &I.I., Strickland, J. D. H., ANAL.CHEM.27, 1778 (1955). (11) Weiss, J.. Allen, A4.O., Schwarz, H. A., International Conference on the Peaceful Uses of Btomic Energy, A/CONF. 8/P/155, USA, June 1955.
(12) White, J. F., Am. Dyestuff Reptr. 31, 484 (1942). (13) White J. F., Taylor, 31.C., Vincent, G. F., Znd. Eng. Chem. 34, 787 (1942). (14) Woodward, E. R., Petroe, G. A., Vincent, G. P., Trans. Am. Inst. Chem. Engrs. 40, 271 (1944).
RECEIVEDfor review August 8, 1963. Accepted December 26, 1963. Research supported by Atomic Energy Commission, Contract No. AT 30-1-1824.
Viscosities of Cellulosic Polyelectrolytes in Organic Solvents Containing Potassium iodide M. E. ROWLEY and E. K. GRUSCHOW Cellulose Technology Division, Eastman Kodak Co., Rochester, N. Y.
b The sodium salts of cellulose acetate sulfate, propionate sulfate, butyrate sulfate, ethylcellulose sulfate, acetate succinate, and acetate phthalate show anomalous viscosity at low concentrations in water. When dissolved in dimethylformamide or dimethylsulfoxide containing 1 to 5% potassium iodide and 0 to 15% water the viscosity was eliminated, ma king it possible to obtain intrinsic viscosities by extrapolation. Solubility of these derivatives was dependent on a proper balance of ionizable and organic substituents. Comparison of viscosities of sulfated polymers in dimethylsulfoxide- 1 % potassium iodide and iron-sodium tartrate suggests that the polyelectrolytes were well dispersed in the organic system.
T
HE OBJECT OF THIS STUDY was t o find a solvent in which the intrinsic viscosities of water soluble cellulose derivatives containing ionizable substituents could be measured and compared. The polyelectrolytes investigated were the sodium salts of cellulose
I I3 00
1
1
1
1
1
1
1
1
L2 C4 06 08 Corceitration, g ester/
1
1
~
tions were prepared b y adding 1%, 3%, and 5% potassium iodide (Baker and Adamson, Reagent Grade). The required amount of dried cellulose ester was dissolved in 100 ml. of the solution, and flow times were determined in an Ostwald-Cannon-Fenske viscometer at 25’ C. -4 viscometer was selected that gave a flow time of approximately 40 seconds for D M F and 70 seconds for DMSO Calculations. INTRIPI’SIC VISCOSITY. Relative viscosities were measured a t three or four concentrations and intrinsic viscosity was determined b y extrapolation to zero concentration of the logarithm of specific viscosity divided by concentration (ad,/c) against concentration. INHERENT VISCOSITY. The relative viscosity was measured at a single cellulose concentration and the inherent viscosity calculated by the following equation :
Inherent viscosity values below 1 are essentially the same as intrinsic viscosity values; values above 1 are slightly lower.
EXPERIMENTAL
0
OC m
SOIU*W
Figure 1 . Anomalous viscosities of a sodium ethylcellulose sulfate and sodium cellulose acetate sulfate in dimethylsulfoxide and dimethylformamide
616
ester and ether sulfates and cellulose derivatives containing carboxyl in the substituent groups. Mench (3) has shown that mater solutions of the sodium salts of cellulose sulfate, carboxymethylcellulose, and cellulose acetate phthalate gave abnormally high viscosity values a t low concentrations. Flory ( 1 ) and Tanford (5) have reviewed previous work on noncellulosic polyelectrolytes and have proposed explanations for these abnormally high viscosities. This anomalous viscosity arises from the ionic nature of the polyelectrolytes, the configuration of the polyelectrolyte in dilute solution being greatly expanded bythe electrostatic repulsion between the like-charged groups, These ionic effects can be eliminated by the presence of excess electrolyte (as a n inorganic salt) in the water solution. The salt prevents the electrolyte from dissociating, thus causing it to behave like a neutral macromolecule. Strauss and Fuoss (4) used a n ethanolwater solution with dissolved lithium bromide on both sides of the osmometer to suppress anomalous osmotic pressures a t low concentrations of a polyelectrolyte. We were able t o dissolve the sodium salts of cellulose acetate sulfate, propionate sulfate, and butyrate sulfate in iron-sodium tartrate (FeTNa), but sodium salts of cellulose ether sulfates were not soluble in this medium. This paper describes a procedure for dissolving a wide range of cellulosic polyelectrolytes so as t o avoid anomalous viscosities.
ANALYTICAL CHEMISTRY
Solutions for Viscosity DeterminaT h e solvents were dimethylformaniide ( D M F ) and dimethylsulfoxide (DMSO), t h e former Eastman Grade a n d t h e latter Technics1 Grade. T h e solutions for viscosity determina-
tions.
Figure 2. Intrinsic viscosities of a sodium ethylcellulose sulfate and sodium cellulose acetate sulfate in dimethylsulfoxide and dimethylformamide with 3% potassium iodide
SODIUM SALTS OF CELLULOSE SULFATE DERIVATIVfS 40
E
+ACETATE -EIHYL 06
ETHER
Table I.
A
-z
+BUTYRATE
04
hd
01 00
Concentrotion, g ester/l(Oml solution
Inherent Viscosities" of Free Acids and Their Sodium Salts
Sample DMF-17, K I Celluloee acetate succinate ... Cellulose acetate succinate ( S a salt) ... Cellulose acetate phthalate 1.33 Cellulose acetate phthalate ( S a salt) 0.89 a Concentration on a cellulose basis.
Figure 3. Intrinsic viscosities of sodium cellulose sulfate derivatives in pot a s si urn d i met hy Is uIf o xi d e-- 1 iodide
70
Table II.
DMSO-17, KI
DMSO :HZ0 (85:15)-1% KI
DMSO
1.75
1.73
1.77
insol.
1.70
Insol.
1.29
1.25
1.38
0.86
1.15
Insol.
Effect of Potassium Iodide Concentration Intrinsic viscositiesa
Dimethylsulfoxide lYOKI 37,KI 57,KI
RESULTS AND CWXJSSION
Water Solutions. Sodium ethylcellulose sulfate and sodium cellulose acetate sulfate samples mere insoluble in a 1% aqueous solution of potassium iodide. When thefe same samples were first dissolved in water, t h e ester precipitated immediately upon t h e addition of 1 % potassium iodide. For this reason, visoosity determinations in aqueous solutions were not investigated. Organic Solutions. Dimethylsulfoxide (DMSO) anll dimethglformamide ( D l I F ) are s d v e n t s for many water-soluble cellulose derivatives. These solvents were used t o determine t h e viscoqities of A sodium ethylcellulose sulfate a n d A sodium cellulose acetate sulfate (Figure 1). The plots are not straight 1inl.s and show abnormally high value? of q a p / c a t the lower concentrations 3f ester. When these celluloce derivatives were dissolved in the orgsinic solvents containing 37, potassium iodide, a straightline relationship (Figure 2) was obtained, nhich can readily be extrapolated to zero concantration to find intrinsic viscositieq oj the esters. Comparison of Viscosities of a Polymer in the Acid and Salt Forms. T h e following evpei iments were designed t o determir e the conditions under which t h e viscosity of a polyelectrolyte in these organic solutions is not influenced by the ionizable substituents. A cellulo-e acetate phthala t e a n d cellulose slcetate succinate were chosen since sulfate esters are unstable in the free acid form. Viscosity measurements were inade on the free acids and the sodium salts which are more highly ionizeL in the organic solutions. Table I shows that viscosity values for the acetate phtha ate sodium salt in DMF-l% KI and ClMSO-l% K I are considerably loner than for the free acid. Since we had noted that these samples were very slo1v in dissolving, the
Dimethylformamide Sample 1%KI 3Y0KI .570K1 Sodium cellulose acetate sulfate 1.14 1.05 1.10 1.17 1.02 0.98 Sodium ethylcellulose sulfate 0.59 0.59 0.60 0.62 0.61 0.63 By extrapolation; concentration on an ester ba.sis.
2 24-
.u
1
.
u 2.0"Lo ._ .-
-=
16-
,'
1.2-
IJTA ,'
08-
fROY 21 SAMPLES OF CELLULOSE
0.4-
L 1
00
~
01
l
02
~
03
l
04
L
05
I
06
~
i
~
I
1~
Lcq of relative viscosity ( 0 4 % concn)
Figure 4. Comparison of viscosity relationships of cellulose and sodium cellulose acetate sulfate in iron-sodium tartrate
DMSO-1% K I solution was altered by the addition of 15% water. I n solutions with added water we found t h a t the inherent viscosities of the free acids were very nearly the same as the corresponding sodium salts; the inherent viscosities of the cellulose acetate phthalate and cellulose acetate succinate free acids were the same for the aqueous and anhydrous solutions; and the cellulose acetate succinate sodium salt was soluble; it was insoluble in the anhydrous solution. I n another set of experiments, sodium ethylcellulose sulfate had an inherent viscosity value of 0.58 in the DMSO3% K I solution, 0.60 in 90% DMSO: 10% water-l% KI, and 0.51 in 70yG DMSO: 30% water-1yG K I . These facts show that the ionizable substituent does not influence the viscosity when the solutions contain the proper amount of inorganic salt and in
some cases the appropriate amount of water. Potassium Iodide Concentration. Table I1 shows the intrinsic viscosities of sodium cellulose acetate sulfate a n d sodium ethylcellulose sulfate in dimethylsulfoxide and dimethylformamide obtained by extrapolation. The intrinsic viscosity is not influenced by increasing the potassium iodide concentration from 1 to 5%. The viscosities are also approximately the same l for the two solutions. The solutions containing 1% potassium iodide were ubed in most of the work t o prevent salting out of polyelectrolytes of borderline solubility at higher levels of potassium iodide. Cellulose Sulfate Derivatives. Figure 3 shows t h a t four different types of sulfated cellulose derivatives gave straight-line relationships in
L
'c
00
0
-ACETATE
A
- BUTYRATE
05
1.0
,
15
I
20
Inherent viscosity in FeTNo
(cellulose basis)
Figure 5. Comparing inherent viscosities of sodium cellulose acylate sulfates in iron-sodium tartrate and 0 p o to s siurn d i met h y Is uIf o x i d e- 1 7 iodide on a cellulose basis VOL. 36, NO. 3, MARCH 1964
617
Table 111.
Inherent Viscosities of Sodium Cellulose Acylate Sulfates in DMSO-1 % KI
Sodium cellulose acylate sulfates Butyrate Propionate Acetate Propionate Acetate Acetate Acetate Propionate Acetate Acetate Acetate Acetate Acetate Acetate Acetate Acetate Acetate Acetate
% Acyl
% NaSOp
39.0 34.4 34.0 27.0 31.0 30.7 27.4 26.1 30.0 29.0 27.5 20.7 23.2 18.7 24.2 18.7 17.0 12.9
17.0 15.1 16.1 15.4 18.3 19.3 17.5 18.0 19.6 20.5 20.5 17.0 21.8 22.9 31.7 30.8 29.8 40.8
Wt. ratio Inherent viscosityb acyl/NaS03 DMSO-l% KI” 2.3 2.3 2.1 1.8 1.7 1.6 1.6 1.5 1.5 1.4 1.3 1.2 1.1 0.8 0.8 0.6 0.6 0.3
1.05 3.15 3.10 2.84 1.60 1.74 1.63 2.62 1.77 1.88 2.97 1.89 2.58
Insolubled Insolubled Insolubled Insolubled Insolubled
Recalculated from per cent combined sulfur. Concentration on a cellulose basis. The last 7 samples were insoluble in DMF-l% KI. Insoluble in DMSO:H20(85:15)-l% KI.
of 27 samples of cellulose as determined by Glegg and Poillon (2). These points conform t o the line within a standard error of *0.05. The points superimposed on this line are for similar determinations of four sodium cellulose acetate sulfates dissolved in FeTNa after correcting for the weight of substituents. The samples contained from 5.2% to 21.6% XaSO3. This close agreement between the cellulose and cellulose derivative viscosities suggests that the complex formation of FeTNa with cellulose is not basically altered by the presence of sulfate groups. Figure 5 shows the relationship between these values in FeTNa and those in DAMSO-l% K I (Table 111). This straight-line relationship passing through the origin suggests that the sulfated polymers are probably well dispersed in the DMSO-l% K I and that the viscosity values can be used as a n indication of the degree of polymerization. LITERATURE CITED
DMSO-1OJ, K I without added water. Therefore, cellulose ester sulfates with varying acyl and sulfate contents were tested (Table 111). Samples having a weight ratio of acyl/NaS03 of 1.1 and greater were soluble over a wide viscosity range. Samples with a weight ratio of 0.3 t o 0.8 were insoluble. (Similar insolubility was found in DMF-l% KI for t h e same series but extended t o a ratio of 1.2.) I n addition, samples containing only ionizable substituents (sodium carboxymethylcellulose and sodium cellulose sulfate) were insoluble in both solutions. Therefore,
the solubility is dependent on a balance between organic and ionizable substituents on the cellulose structure. Inherent viscosities for the sodium acylcellulose sulfates listed in Table 111 were also determined in iron-sodium tartrate (FeTNa). I n this strongly alkaline solution the acyl but not the sulfate groups are removed. Therefore, the viscosities in FeTNa are determined on a sodium cellulose sulfate. The line in Figure 4 sbows the relationship between the relative viscosity in FeTNa, at 0.4% concentration, and the intrinsic viscosity determined by extrapolation
( 1 ) Flory, P. J., “Principles of Polymer Chemistry,” p. 629-37, Cornel1 Univertjitg Press, Ythaca, N. Y., 1953. (2) Glegg, R. E., Poillon, W. N., un-
published data, Eastman Kodak Co., Rochester 4, N. Y., 1958. (3) Mench, J. W., unpublished data, Eastman Kodak Co.. Rochevter 4, N. Y.,
1950. (4) Strauss, U. P., FUOSS, R. hl., J. Polymer Sci. 4 , 4.57 ( I 949). ( 5 ) Taoford, C., “Physical Chemistry of Macromolecules,” pp. 489-508, Wiley, New York, 1961.
RECEIVED for review September 23, 1963. Accepted December 5, 1963. Division of Cellulose, Wood and Fiber Chemistry, 145th Meeting, ACS, Kew York, N. Y., September 1963.
Direct Determination of Sulfur Forms in Green River Oil Shale JOHN WARD SMITH, NEIL B. YOUNG, and DALE 1. LAWLOR laramie Petroleum Research Center, Bureau of Mines,
b Pyrite, organic, and sulfate sulfur in Green River oil shale are determined directly by the method presented. Quantitative, interferencefree chemical separations are performed consecutively on the same sample. Key to the determination is a new method for decomposition of pyrite by lithium aluminum hydride reduction. For pyrite sulfur, the relative standard deviation of the determination i s about =tl.5% of the determined value, and for organic With this new sulfur about *6%. method, forms of sulfur in Green River oil shale can be determined with 618
0
ANALYTICAL CHEMISTRY
U. S.
Department of the Inferior, laramie, Wyo.
precision and accuracy satisfactory for composition studies. The classical Powell and Parr method produces erroneous results.
0
SHALES of the Green River formation in Colorado, Utah, and Wyoming represent a tremendous reserve of fossil fuel energy, equivalent to more than 1 trillion barrels of oil ( 7 ) . The Federal Bureau of Mines, under its policy of encouraging development of this energy resource, is characterizing Green River oil shales. I n this study, a knowledge of the forms IL
and amounts of sulfur present in the rock is vital for determining the composition, heating value, and thermal degradation properties of the oil shales. In Green River oil shale, sulfur occurs in both inorganic and organic combinations. The rocks, essentially siliceous dolomites containing various amounts of organic matter ( I I ) , were formed from sediments accumulated in thermally stratified Eocene lakes (3). I n the reducing environment produced by this stratification, hydrogen sulfide was generated by bacterial attack on organic matter and sulfates in the ooze. Thia hydrogen sulfide precipitated
