Fractionation of Barium-Radium Mixtures as Chromates By Precipitation from Homogeneous Solution SIURRELL L. SALUTSKY, JOSEPH G. STITES, JR., AND A. W. MARTIR’ Mound Laboratory, Monsanto Chemical Co., Miamisburg, Ohio precipitations are made, but is not affected by the composition (barium-radium ratio) of the original mixture or the concentration of barium in solution. In order to compare the separation obtained by the fractionation of various salts, regardless of the precipitation conditions, a theory is presented based on the determination of limiting distribution coefficients. The separation obtained per fractionation step by the homogeneous chromate procedure was equivalent to that obtained by the fractional crystallization of the bromides and better than that by the fractionation of the chlorides or nitrates.
Fractional precipitation from homogeneous solution was investigated as a method for the rapid concentration of radium from barium-radium mixtures. When chromates were homogeneously precipitated, radium concentrated in the crystals with a logarithmic type of distribution. Homogeheous precipitation resulted when nitric acid solutions of the chromates were gradually neutralized, using urea or potassium cyanate as an internal reactant to generate ammonia uniformly throughout the solution. Experiments indicated that the separation is improved by decreasing the temperature at which the
R
ADIUM is usually separated from barium by fractional crystallization of a barium-radium chloride or bromide mixture ( I , $ 8,16). The method depends on the fact that a greater percentage of radium than barium crystallizes a t each fractionation step. Fractional crystallization is a reliable method and has been used to good advantage in separating this pair of chemically similar elements. However, the separation is laborious and slow, and its operation requires considerable space. As separation procedures involving fractional precipitation are generally more rapid than those using fractional crystallization, numerous investigations (18) have been carried out in an attempt to develop suitable fractional precipitation procedures. This paper deals with the conditions for the concentration of radium by the fractional precipitation of barium-radium chromate mixtures. Chromates were chosen for a series of radium enrichment studies because a survey of the literature (18) indicated that chromates gave better separations than any other salt, and because fractional precipitation could be used rather than the more time-consuming fractional crystallization. RADIUM DISTRIBUTION LAWS
When a radium salt is coprecipitated with a barium salt, there are two systematic ways in which radium may be distributed in the crystals. One type of distribution is expressed by the homogeneous distribution law introduced by Henderson and Kracek (6) in which the radium-barium ratio in the precipitated crystals is proportional to the radium-barium ratio in the final solution:
where D is the homogeneous distribution coefficient. The distribution law represents a state of true thermodynamic equilibrium in which the solid phase has been digested sufficiently to re move all concentration gradients and is homogeneous. A second type of radium distribution is characterized by the logarithmic distribution law derived by Doerner and Hoskins ( 4 ) and is expressed by the following equation : total R a log R a in solution
total Ba - A log Ba in solution
where A is the logarithmic distribution coefficient. In this case a state of true thermodynamic equilibrium should exist a t all times with respect to the solution and an infinitesimal surface layer on the crystal (but not with the crystal as a whole, which retains a
radial concentration gradient). Accordingly, if the thermodynamic system is restricted to the surface layer of the crystal and to the solution in equilibrium, the two distribution laws become identical. However, as it is difficult to measure the surface concentration accurately, it is customary to analyze the crystal as a whole. Thus the simple distribution must be integrated over the period of crystal growth which results in the logarithmic relationship. Bonner and Kahn ( 2 )reviewed the literature and described the types of distribution obtained under various precipitation conditions when a radium salt is coprecipitated a i t h a barium salt. For a given set of ideal conditions nhich lead to homogeneous distribution, the calculated values of D remain constant while the values of X decrease as the amount of barium salt precipitated increases. Conversely, for a set of ideal conditions which lead to logarithmic distribution, the values of h remain constant while the values of D increase as the amount of barium salt precipitated increases. The value obtained for D under the conditions N hich lead to homogeneous distribution, theoretically, should equal the value of A under the conditions whkh lead to logarithmic distribution. Since it is difficult to maintain experimental conditions which exclusively favor one type of distribution, the distribution laws do not adequately describe the major portion of the work that has been done on the distribution of radium in barium salts. Generally, neither D nor is constant, but each shows a trend with the fraction of barium salt crystallized or precipitated (9). Xevertheless, the distribution theories are helpful in selecting a practical method for the separation of barium and radium. Distribution coefficients greater than unity represent radium enrichment in the precipitate, while those less than unity represent enrichment in the filtrate. The salt selected for a separation of barium and radium should be one which shows extreme values of D and A. If the separations are to be as efficient as possible, methods leading to the logarithmic type of distribution should be employed (2). For example, if the value of the distribution coefficient is 10, precipitation of 50y0 of the barium removes 99.8% of the radium if the radium is logarithmically incorporated in the crystals, but only 90.9 % if it is homogeneody incorporated. HOMOGENEOUS PRECIPITATION
I n the procedures used by Henderson and Kracek (6) and by Xikitin (14) for the fractional precipitation of barium-radium mixtures, rapid precipitation of the chromates p a s made by the addition of a precipitating reagent. In this type of precipitation, which is often called heterogeneous precipitation (5),the degree
1677
1678
ANALYTICAL CHEMISTRY
of local supersaturation caused by the addition of the precipitating reagent is so erratic that a somewhat random distribution of radium is obtained. I n the fractionation procedure described in this paper the chromates are precipitated in a manner which approaches about as closely as possible the ideal conditions for the logarithmic type of distribution with its added increase in efficiency. The procedure is frequently referred to as precipitation from homogeneous eolution (5, 23). It can be controlled simply, provides uniform results, and is rapidly carried out. The procedure depends upon the decrease in solubility of the chromates vith decreasing acid concentration. By gradual neutralization the solution becomes alightly supersaturated and, thus, the radium and barium chromates precipitate. To fulfill the requirements of a homogeneous aqueous phase (required for thermodynamic equilibrium), the neutralizing base (ammonia) is generated uniformly throughout the solution by spontaneous hydrolysis of a previously added reagent, urea (24) or potassium cyanate ( 1 7 ) . The mechanism for the hydrolysis of urea was reported by Warner ( 2 2 ) : OCN-
+ HaO+
+
NH3
Table I.
Concentration of Radium by Fractional Chromate Precipitation Barium,
G.
Fraction Original
6i 35 17 8 4 2 1 0
1 2 3 4
5 6 7 First concentrate 8 9 10 11
12 Second concentrate 13 14 15 16 17 18
Final concentrate
.
92 62 07 72 72 28 19 71
3.467 1 478 0 924 0.252 0 . 3395 0.0863 0.2418 0.1538 0.0512 0.0215 0.0066 0.0017 0 0003 0.00021
Radium, JIg.
Distribution Coefficient,
0 7007 0 6715 0 6356 0 6088 0 5898 0 3590 0 5309 0 5136 1.680 I ,502 1 388 1.097 0 928 0 882 2.135 2 035 1.735 1.669 1.522 1.209 1.176 1.172
A
4 28 4 49 4 43 4 45 4 59 4 05 3 77 , . ,
4.04 2.63 4.91 2.32 3.12
...
3.03 4.73 6.00 6.62 5.31 18.57(?) 4 73
Ba:Ra Ratio 9 6 , 930: 1 5 3 , 0 5 0 :1 2 6 , 8 6 0 :1 14,320: 1 8,003 : 1 4 , 0 7 9 :1 2 , 2 4 1: 1 1 , 3 8 2 :1 2.064:l 984:l 666: 1 230: 1 150: 1 98:l 113:l 75.5:l 29.5:l 12.9:l 4.3:1 1.4:1
0.26:l 0.18:l
+ CO,
From examination of the above reactions it is obvious that either urea or a cyanate will hydrolyze to produce ammonia. Boiling solutions are required for the isomeric conversion of urea to ammonium cyanate in the first step of the hydrolysis. By using a cyanate instead of urea, it is possible to precipitate the chromates a t any temperature between the freezing and boiling points of the solution. The temperature a t which the precipitation is made can be significant. Merkulova ( 1 2 ) reports t h a t the radium distribution coefficients, D, obtained from fractional recrystallization studies increase with decreasing temperature. Three variables were studied to determine their effects on the distribution coefficients obtained by fractional chromate precipitation from homogeneous solution: radium concentration in the original barium-radium mixture, barium concentration in solution, and temperature. RADIUM CONCENTRATION STUDIES
The radium concentration with respect to barium was varied over a wide composition range by using a simple batch fractionation system (11,19)in which 50% of the barium was precipitated in each fractionation step. The temperature a t which the precipitations &-eremade was 100' C. One hundred grams of a barium-radium carbonate mixture (Ba: Ra = 96,930: 1)was moistened with 250 ml. of water and dissolved by slowly adding 100 ml. of concentrated nitric acid. After dilution with water to 3 liters, the nitrate solution was heated to 95' C. Fifty grams of potassium chromate, dissolved in 200 ml. of hot, dilute nitric acid (1 to 3 ) , and 192 grams of urea were added to the solution. The reaction mixture \vas maintained a t 100' C. until sufficient urea hydrolyzed to raise the pH to 5. Barium-radium chromate precipitated and was filtered. The radium-enriched precipitate, vhich contained about half the originalquantity of barium, was dissolved in 800 ml. of hot 1N nitric acid. The solution was diluted with 2.4 liters of hot water. After the addition of 192 grams of urea, the temperature R-as maintained a t 100' C. for 42 minutes. A second fraction of barium-radium chromate precipitated. The precipitation was stopped by the addition of a few milliliters of cold water to cool the solution below 90" C. The precipitate was filtered immediately and used in a third fractionation step. All subsequent fractionations were carried out in the same manner as the second step, except that in each step the amounts of reagents were reduced to one half of that required in the preceding step. For example, the second barium-radium chromate fraction was dissolved in 400 ml. of 1 nitric acid. The solution was diluted with 1.2 liters of water, and 96 grams of urea was added. The fourth fractionation step required only 200 ml. of 1 S nitric acid, 600 ml. of water, and 48 grams of urea. The fifth step required half the amounts used in the fourth step, etc.
Radium was determined in the filtrate from each fractionation step by the method of Tompkins and coworkers (20), and the radium in the precipitate was obtained by difference. Barium n as determined by drying and weighing the precipitated chromates. The fraction of barium precipitated in each fractionation step (except the first) depended on a timed reaction, based upon the rate of hydrolysis of urea in hot solution. If the reaction mixture is maintained at 100" C. for 42 minutes, approximately 50% of the barium chromate precipitates. For each minute over 42 minutes an additional 3% of the barium chromate is precipitated; therefore, time control is critical. Bpcause of the rapid changes in fraction sizes, individual samples could be fractionated only si\ or seven times before becoming very small. A sample of sufficient size to continue the separation process was obtained by mixing fraction i from several fractionation series. This sample, called the "first concentrate" in Table I, contained 3467 mg. of barium and 1.680 mg. of radium (Ba:Ra = 2061: 1). In a similar way, a "second concentrate" containing 241.8 mg. of barium and 2.138 nig. of radium (Ba:Ra = 113:l) was prepared by mixing fraction 12 from several series. BARIUM CONCENTRATION STUDIES
Concentrations of 5 , 10, 20, and 30 grams of barium per liter of solution were studied. The carbonate sample used for these studies had a barium-radium ratio of approximately 100,000 to 1. Since radium was present only as a microcomponent, the weight contributed by it was neglected. In each experiment about 20% of the barium was precipitated.
A weighed sample of the barium-radium carbonate was dissolved in sufficient 1 A- nitric acid so that the final solution would have a pH of 1.2. After the addition of 5 ml. of glacial acetic acid, the solution was diluted with water to 500 ml. A quantity of potassium dichromate calculated to precipitate 20% of the barium was dissolved in the solution. Finally, 4 grams of potassium cyanate dissolved in a few milliliters of Tvater mas added, Precipitation was complete in about 20 minutes. The mixture was filtered, and the precipitates were analyzed for barium gravimetrically and for radium radiometrically (20). TEMPERATURE STUDIES
Fractional chromate precipitations were made a t loo", 25', and 0" C. on a sample of fixed composition (Ba:Ra = 100,000:1). At each temperature the percentages of radium carried by the precipitation of various percentages of barium were determined. The fraction of barium precipitated in each experiment was fixed
V O L U M E 25, N O . 1 1 , N O V E M B E R 1 9 5 3 by the quantity of potamium dichromate added to the original solution. The initial barium concentration in each solution was always 10 grams per liter of solution. The reaction mixture was prepared by adding 100 ml. of water to 7.4 grams of a barium-radium carbonate mixture (equivalent
to 5 grams of barium) and dissolving the carbonate by the addition of 7 ml. of 16 b nitric acid. If the experiment was to be carried out a t 0" or 2.5" C., 5 ml. of glacial acetic acid was then added. The solution 'ivas diluted to approximately 490 ml., and the desired amount of potassium dichromate was added. Depending upon the temperature a t which the precipitation was to be made, either 30 grams of urea or 5 grams of potassium cyanate in 10 ml. of water was added.
Y
0
,
10
Figure 1.
do
3b sb sb PER CENT BARIUM PRECIPITATED
io
7b
do
9b
Effect of Temperature on Fractionation of Barium-Radium Chromates
For the reactions carried out a t 100" C., urea was used as the internal reactant. (Potassium cyanate was not used because of its uncontrollable, rapid rate of hydrolysis a t 100' C. j During the neutralization, the pH of the solution changed from the original value of 1.2 to approximately 6. Since barium chromate is practically insoluble a t a p H of 6, the supernatant liquid was nearly colorless. The precipitate was filtered, and the bariumradium mhture remaining in the filtrate was recovered as the carbonate. For reactions carried out as 25" C. (room temperature) and a t 0" C., potassium cyanate was used as the internal reactant. At room temperature precipitation started approximately 3 minutes after the addition of the cyanate and was complete, as evidenced by the color of the supernatant liquid, in about 20 minutes. The procedure a t 0" C. required that the reaction mixture be cooled in an ice bath before the addition of the potassium cyanate. The precipitation was complete in about 2 hours. In all experiments barium and radium were determined in both the solid and liquid phases. The fraction of barium in each phase was determined gravimetrically. Radium was determined by the alpha-counting method (20). The acetic acid acted as a buffer for the reaction in order to prevent the precipitation of barium and radium carbonates which have a reverse order of solubilities compared to the chromatesLe., radium carbonate is more soluble than barium carbonate (IO) The acetic acid buffer was not required for the precipitations made a t 100" C., as the carbon dioxide was removed by boiling the solutions. The coprecipitation of a small quantity of nitrates was obeerved a t 0" and 25" C. Qualitative tests applied to many separate washes of the chromate precipitates with hot water indicated the presence of both barium and nitrate ions. The radium enrich-
1679 ment was not improved by washing the precipitates] as proportionate quantities of radium were also removed from the crystals. The coprecipitation of barium nitrate with barium chromate was not observed in precipitations a t 100' C. RESULTS AND DISCUSSION
The concentration of radium by fractional chromate precipitation is shown in Table I. In 19 fractionation steps the composition of the sample changed from an original barium-radium ratio of 96,930 to 1 to a final ratio of 0.18 to 1. The logarithmic distribution coefficient] A, for each step was calculated from the results of the barium and radium determinations in the various fractions. Although the radium concentration with respect to barium was varied over a very d d e composition range, the radium distribution coefficients remained relatively constant. No explanation can be given for the anomalous value obtained for fraction 18, except that it was probably due to analytical errors. The percentage of radium in the "final conrentrate" (84.8% radium) is only slightly below that of commercial-grade radium. The radium chromate m a s a bright yellon salt resembling barium chromate. The salt glowed weakly in a darkened room .i\ith the characteristic light of radium salts. Table I1 shows the effect of barium concentration on the radium distribution coefficient. .4lthough the barium concentration was varied from 5 to 30 grams per liter of solution, the calculated logarithmic distribution coefficients show no particular trend over this composition range. Therefore, it appears that the barium concentration has no effect on the distribution coefficient.
Table 11. Effect of Barium Concentration on Distribution Coefficient Barium Concentration, G./L. 5 5 10 10 20 20 30 30
Table 111. Barium Precipitated,
70
Barium Precipitated,
Radium Carried,
Distribution Coefficient,
21.6 21.4 22.1 21.9 22.5 22.8 22.9 22.2
77.2 78.8 75.7 79.6 76.5 79.7 82.7 79.9
6.06 6.45 5.66 6.44 5.69 6.17 6.74 6.40
70
x
%
Effect of Temperature on Distribution Coefficient Radium Carried,
%
Distribution Coe5cienk D
A
20.6 20.9 25.2 25.2 35.8 37.3 48.5 50.6 52.4
Temperature 100' C. 65.3 7.25 67.9 8.01 69.8 6.86 75.3 9.05 88.6 13.94 86.9 11.15 91.9 12.05 95.2 19.36 94.3 15.03
4.59 4.85 4.12 4.82 4.90 4.35 3.75 4.39 3.86
6.0 11.3 11.7 21.9 22.1 22.2 27.9 33.4 34.1 43.7 43.8 54.5 64.5
Temperature 25' C. 29.7 6.62 50.3 7.95 50.6 7.73 13.91 79.6 75.7 10.98 11.73 77.0 16.42 86.4 17.56 89.8 17.20 89.9 25,Ol 95.1 17.59 93.2 63.39 98.7 109.5 99.5
5.69 5.83 5.78 6.43 5.66 5.86 6.10 5.62 5.50 5.25 4.66 5.51 5.12
5.5 9.8 20.1 23.4 29.8
Temperature 0" C. 39.4 11.17 56.2 11.81 83.2 19.69 86.6 21.13 92.7 29,92
8.84 8.00 7.95 7.54 7.40
ANALYTICAL CHEMISTRY
1680 A graphical comparison of the separation of barium and radium loo", 25', and 0" C. is made in Figure 1. Curves obtained by plotting the percentages of radium and barium precipitated (Table 111)are compared with a line which represents no separation. As the displacement of a curve from the "line-of-no-separation" is a measure of the attainable separation by a given procedure, it is obvious that the lower the temperature the greater the separation of barium and radium. Radium distribution coefficients,D and X, were calculated using the percentages of barium and radium precipitated and the equations which define the two distribution laws. These distribution coefficients are shown in Table 111. It is obvious that the logarithmic distribution law is more applicable than the homogeneous distribution law, as the A values remain relatively constant while the D values increase rapidly with increasing amounts of barium precipitated.
at
Y
=7l
A 100.C
"Ld
3
PER CENT BARIUM PRECIPITATED
Figure 3.
Effect of Temperature on Limiting Distribution Coefficient
fractionation system the limiting values of D and h are equal. The use of limiting values of the distribution coefficients affords a method of direct comparison of the separation obtained by the fractionation of various salts regardless of precipitation conditions, From data in the literature, limiting distribution coefficients for the fractionation of barium-radium chlorides, bromides, and nitrates were obtained by plotting the percentages of barium
I Table IV. Effect of Temperatureon Limiting Distribution Coefficients of Several Barium-Radium Salts
rJ
-0
0
'
lo
2o
'
40
?&&,Tu&.
50
Sb
70
8b
$0
I
Limiting Distribution Coefficient
lbo
Figure 2. Variation of Distribution Coefficient with Per Cent Barium Precipitated
5.1
5.3 4.5 Av. 5.0 3.4
Actually, a slight deviation from the logarithmic distribution law is observed when the calculated A values and percentages of barium precipitated are plotted (Figure 2). It is evident that the X values show a trend toward smaller values when larger fractions of the barium are precipitated. The straight line through each set of pointa was determined by the method of least squares. Even though the radium is originally deposited according to the logarithmic distribution law, the increased contact time of crystals and mother liquor in an agitated solution favors the homogeneous distribution of radium. Therefore, a slight decrease in A is to be expected with increased contact time. This trend is most evident for the experiments made a t 0" C., where the crystals of barium chromate were in contact with the mother liquor longer than in the experiments a t the higher temperatures. The logarithmic distribution constants that would be obtained under ideal conditions-i.e., instantaneous precipitation and removal of the crystals from the mother liquor-may be determined from Figure 2 by extrapolating the three l i e s to 0 % barium precipitated. The authors have designated these extrapolated values as the limiting distribution coef%cients. The limiting values for the chromate procedures a t 0", 25', and 100" C. are 8.85, 6.09, and 5.16, respectively. It is significant that the 25" drop in temperature between 25' and 0' C. has a much greater effect on the limiting distribution coefficient than the 75" drop in temperature between 100" and 25' C. A limiting value for the distribution coefficient represents the distribution of radium between the first infinitesimal amount of salt precipitated and ita saturated solution. For any particular
3 7 3.7 3.7 3.6 3.4 4.5 Av. 3.7
Fractionation Conditione Chloride Fractionation, 0' C. Precipitated from supersaturated solutions Slow crystallization Rapid crystallization 200
c.
Rapid crystallization from supersaturated solutions Slow crystallization from supersaturated solutions Slow evaporation from saturated solutions Fractional precipitation with " 2 1 Fractional crystallization by slow cooling 100' t o 200 Fractional crystallization by rapid cooling 100" t o 200 Slow evaporation from saturated solutions 900
c.
2.3
Evaporation from saturated solutions
9.8
Bromide Fractionation, ' 0 C. Slow crystallization 200
6.8 7.6 6.2
Av. 6.9
4.4 3.1 5.7 Av. 4.4
1.8 2.0 2.1
Av. 2 . 0
1.7 1.5 1.4 1.3 1.5 Av. 1.5
c.
Slow evaporation from supersaturated solutions Slow evaporation from agitated saturated solutions Slow evaporation from saturated solutiona
85' C. Slow evaporation Fast evaporation Evaporation on water bath Nitrate Fractionation, 0' C. Slow crystallization Rapid crystallization Rapid crystallization and long digestion 200
c.
Rapid crystallization from supersaturated solutions Slow crystallization from supersaturated solutions Slow evaporation from saturated solutions Slow evaporation Rapid evaporation
Reference
V O L U M E 2 5 , NO. 11, N O V E M B E R 1 9 5 3
1681
precipitated with their corresponding distribution coefficients and extrapolating to 0% salt precipitated. The limiting values are given in Table IV. At a particular temperature and for a particular salt the limiting distribution coefficients are not identical because of the variety of fractionation conditions used. The average values shown in Table IV are probably not too accurate; however, for each salt i t is obvious that the limiting distribution coefficient is dependent upon the temperature a t which the fractionation was made. The effect of temperature on the concentration of radium by the fractional precipitation of several barium-radium salts (chromates, chlorides, bromides, and nitrates) is shown in Figure 3. An increase in limiting distribution coefficient with decreasing temperature is observed, indicating an increasing solubility differential between radium and barium salts with decreasing temperature. In addition, it can be seen from Figure 3 that fractionation of the chromates or bromides is about equally efficient either of which is better than the fractionation of the chlorides or nitrates. LITERATURE CITED
(1) Barker, H. H., and Schlundt, H., Cniv. Missouri B~LZI., 24, No.
26 (September 1923). ( 2 ) Bonner, N. A., and Kahn, M., Nucleonics, 8, KO. 2, 46 (1951). (3) Can. Chem. Met., 17, 251 (1933). (4) Downer, H. A., and Hoskins, W. bI., J . Ana. Chem. Soc., 47, 662 (1925). - ~- - , (5) Gordon, L., ANAL.CHEY.,24,459 (1952). (6) Henderson, L. M., and Kracck, F. C., J . Am. Chem. SOC.,49,738 (1927). (7) Khlopin, V., and Polrssitsliii, A., Z . anorg. aZEga. Chem., 172, 310 (1928).
.-
(8) MacTaggart, E. F., Trans. Inst. Chtm. Engrs. (London),20, 65 (1942). (9) Marques, B. E., Campt. rend., 197, 1314 (1933). (10) Marques, B. E., J . chim. phys., 33, 1 (1936). (11) Ibid., p. 306. (12) Merkulova, M. S., Trav. i n s f . &at r a d i u m (U.S.S.R.), 3, 141 (1937). (13) Mumbrauer, R., 2. p h y s i k . Chmt., A156, 113 (1931). (14) Nikitin, B. A., Compt. rend. m a d . sci. U.R.S.S., (N.S.) I, 19 (1934). (15) Parsons, C. L., Moore, R. B., Lind, S. C., and Schaefer, 0. C . , U. S. Bur. Minea, Bull. 104 (1915). (16) Riehl, N., and Kading, H., Z. physik. C h a . , A149, 180 (1930). (17) Ripan, R., BUZZ.soc. stiinte Cluj, 3, 311 (1926). (IS) Schwind, S. B., and Croxton, F. E., “Radium, A Bibliography of Unclassified Literature,” U. S. Atomic Energy Commission, TID-363 (July 1950). (19) Tipson, R. S., ANAL.CHEM.,22, 628 (1950). (20) Tompkins, P. C., Norris, W. P., Wish, L., Finkle, R. D., and Evans, H. P., “Methods for the Quantification of Radium,” U. S. Atomic Energy Commission, MDDC-699 (June 11,1946) (21) Walter, Z. T., and Schlundt, H., J . Am. Chem. SOC.,50, 3266 (1928). (22) Warner, R. C., J . Bid. Chem., 142, 705 (1942). (23) Willard, H. H., A N A L . CHEM.,22, 1372 (1950). (24) Willard, H. H., and Tang, N. K., J . Am. Chem. Soc., 59, 1190 (1937). RECEIVED for review M a y 13, 1953. rlccepted August 20, 1953. Presented before the Division of dnalytical Chemistry at the 124th Meeting of the A\fERIcAN CHEmcAL SOCIETY, Chicago, 111. Abstracted from u. 8. Atomic Energy Commission MLM-723, “Radium-Barium Separation Process. I. Enrichment by Fractional Precipitation,” Mound Laboratory, Moneanto Chrmical Co., Miamisburg, Ohio, April 1. 1951. Mound Laboratory is operated by N o m a n t o Chemical Co., under A. E. C. Contract AT33-1-gen53.
Methods for Determining Hydrocarbons and Phenols in Water Report of the Subcommittee on ReJinery Efluent-Water Analytical Methods, Committee on Analytical Research, Division of ReJining, American Petroleum Institute C. E. HEADINGTON, Chairman The Atlantic Refining Co., Philadelphia, P a . E. L. BALDESCHWIELER, Standard Oil Dew. Co. T. B . BARRY (deceased), Imperial Oil, Ltd. V. V. BELLINO,Allied Chemical and Dye Corp. J. A. GRANT,Pan American Refining Corp. S . S . KURTZ,Sun Oil Co.
T
H A R R YLEVIN,The Texas Co. J. B. RATHER,J R . , Socony-Vacuum Oil Co. A. R. RESCORLA,Cities Service Research and Development Co. E. B. TUCKER,Standard Oil Co. R . C . WILBUR,Shell Oil Co.
HE necessity for controlled disposition of waste waters is recognized by industry. It is essential for good public relations, and for preserving rivers and lakes in such a condition that they may continue to serve the needs of society. The petroleum industry has a record of achievement in the field of waste disposal. Early developments in oil-water separators have been improved and other waste-treatment methods have been devised in recent years. Regulatory bodies in a number of states have set purity standards for waste effluents. Obviously, test methods are necessary for measuring the performance obtained in wastetreatment processes and for determining the extent t o which these standards are met. The composition of waste effluents is complex and the low concentrations of components make it difficult to obtain analytical accuracy. Recent advances in stream-pollution abatement have brought the industry to a point where future progress will be dependent upon the development of new analytical techniques having greater sensitivity and accuracy for hydrocarbons and phenols (the chief refinery offenders). For instancc, for control of refinery waste oil
determinations accurate to a few parts per million are desirable, and when drinking water supplies are being tested it is desirable to have methods that will measure a few parts per billion of eithcr hydrocarbons or phenols. Because this problem is common to most petroleum refineries, a number of laboratories, working cooperatively through the .imerican Petroleum Institute’s Committee on Analytical Research, have been investigating the analytical aspects of this problem since early in 1948. The material presented here is the result of this cooperative program, out of which have come analytical methods which more nearly approach the accuracy required for today’s waste-control programs. The work of the subcommittee has consisted of stimulating and initiating analytical research in the participating lahoratories and of cooperatively evaluating the techniques made available. Although the work of the group is continuing, a report should be valuable at this time, as the subcommittee has been responsible for the development of five new analytical methods and has cooperatively tested two other procedures, which were then combined into a sixth method.
