1339
SOTES
iiig water through quartz wool and isocyanate sponge held at various compressions. In Table 111, the permeability changes are represented by two factors, t'he solids density and the flow rate per TABLE I11 EFFECT O F 'k'ERMESBILITY t
IF
QuAwrz
T.i.rli.t
h,"
('III.
O S THE STRE.4ILIIXG
EFFICIEXCY
\T-OOL AXTI ISOCYAS.4TE S P O S G E DIAPHRAGILIS .Solids ()/At'. AP/E I/(J Efii'm.3/ X lo-?, X 10-2. ciencs set'.-cm. e . s . i i . / c i i i . 3 e.s.ii./ciri.a x 10s
?';
6.3 5.5 4.8 8 I) 2.3
0.06 .07 .08 .10 .17
,i 2 4.i
,%
I
4. 3.9 3.8 2.6 2.4 2.0 3.0 3.0 3 .0 3 .0 3.0 3 .0 3.0 3.0 01 Diameter of
,26
.2i ,:31 .32 .47 .5l .61 ,05 .08
.0u .13
Quartz wool 0.92 1.21 .82 2.15 .6i 2.29 .66 2.05 .49 2.13 Isocyanate sponge .33 1.22 .20 1.35 .1R 1.40 .I6 1.47 .14 1.51 .04 2.01 .03 2.32 .O1 2.46 1 .OO 1.48 1.(io 1.23
1.30 1.11 0.47 0.95 .38 .19 1.42 .47 .ll 1.59 .53 .04 2.21 .B1 .01 2.84 all diaphragms, 1.1em.
Acknowledgment.-The authors are pleased t o ncknowledge the support of the Armstrong Cork Company whose interest in electrokinetics made this work possible. In addition, the authors wish to thank Mr. M. Z. Nammari for obtaining some of the quartz wool data for this study.
2.10 1.41 1.30 1.74 1.62
1.74 0.65
:3,55 4.34 3.91
2.91 3.22 2.80 3.04 3.35 6.55 7.36 9.07 0.26 0.49 0.60 2.13 2.12 3.10 3.69
4.47
5.07 13.16 17.04 22.30 0.38 .62 .67 2.02 3.00 4.95 8.16 20.50
.57 .85 .76
7.23
unit pressure across the diphragm, Q l A P . A wide range of permeability could not be attained with quartmawool plugs; hence the effect of permeability on efficiency x a s not clearly defined. On the other hand, the permeability of isocyanate sponge was varied in two ways. First, t'he amount of sample was held constant and then compressed t'o various lengt'hs; second, the sample was held at const'ant, length ( 3 em.) and the permeability was varied by changing the packing. Under both conditions the efficiency increased at decreased permeability. The data present'ed show that permeability drast,ically influences the streaming efficiency below a Q,!AP of about. 0.1 ~m.~/sec.-crn.Since this behavior is not predicted by classical theory of streaming potential, much doubt is cast on existing literature which reports streaming data at lorn permeabilities. A similar conclusion has been made by Biefer and In general, streaming potential generation is a very inefficient process with efficiency values in the order of low5, depending upon experimental conditions. The results presented illustrat'e that t8hestreaming potential phenomenon can be a useful tool for studying the solid-liquid interface without employing t'he classical approach. Furthermore, this analysis gives a broad picture of the streaming potential effect which may serve as a basis for future studies in the field. ( 5 ) G . J. 13iefi:r and S. G. AIason, Trans. Faraday Sac., 5 5 , 1239 (19.59).
T H E HEATS OF FUSIOK O F THE CADMIUJI €IAT,IDES, MERCURIC CHLORIDE *IXD BISMUTH BROMIDE BY L. E. TOPOL A X D L. D.
R.4sso~
Atomics International, A Division o f Y o r l h A m e r i c a n Aviation, I n c . Canoga Park, California Reremed March 81, 1960
In the course of invest'igations of molten metalmet'al salt syst'ems in this Laboratory, cryoscopic measurements in CdCl2, CdBrz, CdIz, HgClz arid BiBra solutions have been carried out. Interpretation of these results required an accurate value for the heat of fusion of t'he salt solvent. As the literature values for the heats of fusion of the above salts were all based on cryoscopic measurements and thus, as has been shown in recent calorimetric studies with other s a l t , ~ may , ~ . ~be of doubtful accuracy, a calorimetric study was made to determine these values. Experimental Materials.-CdC12, CdBrn and Cd12 were prepared and purified as described elsewhere.4 BiBra was synthesized from the elements in a similar manner to CdBr2. HgC12, Rlallinckrodt analytical reagent grade, was dried overnight a t 140" i n vucuo. Apparatus and Procedure.-The drop-calorimeter and procedure were identical to those used earlier.* A minimum of six drops over a 60 to 100' range both above and below the melting point of each salt was made. The salt samples, 10 t o 20 g. in weight, mere contained in platinum and were always melted before the measurements were carried out t o ensure intimate contact between the salt and container. In the case of HgClz the possibility of reaction between the salt and container was checked by X-ray fluorescence techniques. Within the sensitivity of the method (0.5% by weight) no platinum was found in the salt phase.
Results and Discussion The calorimet'ric results for CdCl2, CdBr2, CdIz, HgClz and BiBr3 found in this study together with the literature values for the heats of fusion5f6 are listed in Table I. The heat capacities of the salts were assumed to be constant for the limited temperature ranges of the measurements. It is interesting to note that the heats of fusion report'ed in the literat'ure were determined cryoscopically and are lower in every case than the calorimetrically measured values. These lower results might be expect'ed when solute concentrations are not sufficiently dilute to permit accurat,e use of the Raoult-van't Hoff relation. (1) This work was supported by t h e Research Division of the Atomic Energy Commission, ( 2 ) L. E. Topol, S . W. 3Iayer and L. D. Ransom, THIEJOURS.AL, in press. (3) 4 . S. Daorkin and AI. A . Bredig, THISJOVRSAL,6 4 , 269 (1960). (4) L. E. Topol and A. L. Landis, t o be published. ( 5 ) K. K. Kelley, U. S. Bur. Mines Bull. 393, 1936. ( 8 ) L. Brewer, et al., "The Chemistry and Metallurgy of Miscellaneous ,Materials: Tlierniodynaniics," ed. by L. L. Q ~ i i I l ,3IcGraw-Hill Book Go., S e w T o r k , S . Y.,1950.
13-20
5’01. 61
SOTES TABLE I HICAT CI\PACITIES, EIEATS
A N D ESTROPIES OF F U S I O N FOR capacity--
--Heat
Salt
CdClz CdBrz CdIz
HgCh RiBra
(cal./deg./mole) Solid Liquid
28.5 22.8 21.5 19.2 26.0
f 1.5 f 2.0 f 1.6 f0.6 f 1.0
26.3 24.3 24.4 27.2 37.7
CdCI,, Cdnr., CdTz, IIgcI:! A S D
hI.p., OK.
A S f (e.u.)
842.1 841.2 661.2 552.7 492.2
8.57 f 0 . 2 0 9.48 f .OD 7.49 f .20 8.40 f .09 10.55 f .40
f 2.3 f 1.2 f 2.7 i 1.1 f 1.7
The entropies of fusion for these salts are of the same magnitude as those for most inorganic substances, Le., between 2.5 and 3.2 e.u. per gramatom.7 However, for the cadmium halides the highest entropy of fusion exhibited by the bromide is interesting. Since CdC12 and CdBr2 are similar compounds, chemically and structurally, little difference in the entropy of fusion would be expected. The entropy of fusion of BiBre, 10.5 e.u., is somewhat lower than that found for BiC13,*11.2 e.u. As the two salts have similar structures,8 a t least a part of the difference in values may be the result of the solid phase transition which occurs in BiBra a t 15S0.* This transition, observed by thermal analysis, does not involve a change in structure. This fact suggests a maximum entropy and heat effect of 0.7 e.u. and about 0.3 kcal./mole, respectively, are associated with the solid phase change. Such a heat effect was not found in the calorimetry studies, possibly as a result of the rapid cooling of the sample during the measuremeii t E .Q (7) 0. Kubaschewski a n d E. L1. Evans, “Metallurgical Thermochemistry,” Pergamon Press, New York, N. Y., 1958, p. 191. (8) G. M. Wolten a n d S. W. Msyer, Acta Cryst., 11, 739 (1968). (9) Reference 7, p. 1?5.
THE AFFINITY OF CERTAIN DISUBSTITUTED AMIDES AND ORGSNOPHOSPHORUS COMPOUNDS FOR WATER‘ BYT. H. SIDDALL, I11 Savannah River Laboratory, E. I . du Pont de Nemours & Co.. Aiken, South Carolina Received April 11, 1060
Various esters that contain phosphorus have been investigated as extractants for actinide and rare earth elements and for nitric acid. The author also has in process of publication a similar study of extraction by disubstituted amides. However, no extensive study has been reported pertaining to the solubility of water in such compounds. Observations that the volume of samples of dimethyl octylphosphonate increased markedly on being wetted prompted an investigation of water solubility in the octylphosphonate, similar compounds, and in disubstituted amides. Preliminary results of such a study are reported here. The data in Table I shorn that those phosphorus compounds and amides with the dipole group (P=O or C=O) exposed have a strong affinity for (1) T h e information contained i n this srticle was developed during the course of work under contract AT(07-?)-I with the U. 9. dtornic Energy Commission.
---4Hf (kcal./rnole)--This work I.it.6
7.22 7.97 4.05 4.64 5.19
f 0.17 zt .os .1:j
5.30 5.00 :1.66
=t .05
4.15 (4 0 )
+
i .20
-
water. This strong affinity is lost with the d’ethyl amide but persists even with ethyl groups in the phosphorus compounds. It is also qcen that the order of affinity for water is phosphinate > phosphonate > phosphate. These observations allow two conclusions to be drawn. First, the affinity for water depends greatly on the degree of steric hindrance around the dipole group. Longer alkyl chains seem to prevent the accumulation of water molecules around thc dipole group. Second, the affinity for water folloir 5 the same trend as the ability to extract actinide elements and nitric acid from aqueoui nitrate solutions. The order of extractant strength is alw phosphinate > phosphonate > phosphate. Perhaps the most interesting question that arises from the data in Table I concerns the structure of organic phases that contain so much water. It is obvious that as many as 30 moleciiles of water cannot be directly fixed to the organic dipole. Instead the effect of the organic dipole must be propagated through a chain or network of water molecules. However, the normal ability of these water molecules to solvate metal ions is little, if any, impaired. Preliminary experiments s h o w d that for tracer concentrations, the extraction coefficients for cesium, strontium and promethium are all about 0.3 with 0.05 111nitric acid in the aqueous phase and with dimethyl octylphosphonate. Since cesium, in particular, is not very well extracted by esters that contain phosphorus, the extraction must be due to solvation by water. TABLE I WATER SOLUBILITY IN VARIOUSAMIDES
ASD
PHOSPHORUS C O V P O U N D S Weight Temp., Compound % HEO cC.
N,N-Dimethyloctanamide N,N-Diethyldecanamide N,N-Dibutylbutyrsmide Tributyl phosphate Dibutyl butylphosphonate Dimethyl octylphosphonate
26 3.0 3.0 6.4 10.4 71 51 35
30 30 30 30 30 0 30
Diethyl octylphosphonate
43
Octyl diethylphosphinate
22 15.4 59
0 30 60 30
60
OROANOhfole ratio HlO/organic
3.3 0.34 0.34 1.0 1.7
30 13 6.6 11
3.9 2.5 18
Preliminary experiments showed that when nitric acid is extracted, the methyl and ethyl phosphonates lose the ability to extract water. Each molecule of extracted nitric acid removes one phosphonate molecule as a water acceptor. Further experiments with these compounds are
