NOTES
4290
earlier estimates.2) The results were K D = ~ 9.7 X IO2 M - 2 and K D =~ 3.4 X l o 3 The value 2 found for the T B P solvation number of T1C13 agrees with the result of Chuchalin, et al.,’ which was obtained by quite different methods. We consider it well established for straight-chain hydrocarbon solutions. Earlier estimates of the TBP solvation number of HTlC1, differ among themselves and from our provisional value 4. A value 2 was reported8 for isooctane diluent. Studies with benzeneg~l0 gave 3, a value expected on the basis of the model proposed by Tuck and Diamond” for the extraction of strong acids. A solvation number 4 was reported by Rleyers and for HFeC14 in diethyl ether-benzene mixtures. They suggest that in dddition to solvation of the hydrated proton there may be a sufficiently strong interaction of extractant molecules with the anions or with the ion pairs that this additional “electrostatic solvation” plays a significant role in the extraction process. We think this is a reasonable point of view and that the HTlC14TBP-octane system may also be an example. lo-’
10-2
IO0
M [TBP]
Figure 1 . Variation of dislribution ratios with concentration of TBP. Left-hand curve, slope 2.0: extraction of TlC13; [Cl-] 0.0060 MI [H+] 0.04 and 0.05 M . Right-hand curve, slope 4.0: extraction of HTlCla from 0.50 M HCl. Values corrected for extraction of TlC13from this medium.
were calculated from results of Walters and Dodson2 and the present work. An alternative calculation of the corrections was made using the stability constants of T1C13 and TlC14- reported by Woods, et aL6 The difference in the corrected values of D obtained by the two methods is taken as a reasonable estimate of the uncertainty in the corrected value and is indicated by the plus and minus error bars. It is remarkable that within these uncertainties the data for the extraction of HTlC14 are all satisfactorily fit by a straight line of slope 4.0, over a range of lo4 in the corrected distribution ratio. We provisionally adopt the simplest interpretation of this result, which is that the extracted HTlC14 is solvated by four molecules of TBP and that the activity YT is the activity coefficient coefficient ratio y ~ ~ / y(where 4 of T B P and y4 is that of the solvated HTlC14) remains constant up to the highest T B P concentration, 0.73 M . For an ion pair, which the HT1C14.nTBP may be supposed to be, it is not surprising that y4 should vary strongly with increasing polarity of the medium. However, we have no basis for predicting so exact a compensation of effects as appears to prevail. The distribution equilibrium constants were evaluated with the aid of (3), on the basis that m = 2 and n = 4. (The stepwise stability constants of T1Cl3 and TlC14- involved in the calculations were independently determined in the present work and agreed closely with The Journal of Physical Chemistry, Vol. 74, XO.24, 1970
Acknowledgments. We are grateful to F. Silkworth for solvent purification, to James R. White for preliminary measurements on this extraction system, and to Karin Karlstrom and Kathleen JIcLinskey for skillful technical assistance. (6) M. J. M . Woods, P.K . Gallagher, 2 2. Hugus, and E. L. King, Inorg. Chem., 3, 1313 (1964). (7) L. K . Chuchalin, I. A. Kuzin, K . F. Obzherina, T . T . Omarov, and L. S. Chuchalina, Russ. J . I n o ~ g Chem., . 12, 622 (1967). (8) K . Henning and H. Speclter, Z. Anal. Chem., 241, 81 (1968). (9) K. S. Venkateswarlu and P.Chanan Das, J . Inorg. Nucl. Chem., 25, 730 (1963). (10) H. Specker and W. Pappert, 2. Ano~g.Allg. Chem., 341, 287 (1965). (11) D. G. Tuck and R. M. Diamond, J . Phys. Chem., 6 5 , 193 (1961). (12) D . A. Meyers and R. L. McDonald, J . Amer. Chem. Soc., 89, 486 (1967).
Ozone Filter for Selecting 185-nm Radiation from Mercury Vapor Lamps’
by L. C. Glasgow and J. E. Willard Department of Chemistry, University of Wisconsin, Madison, Wisconsin 65706 (Receizled June 17, 2970)
Ninety per cent of the radiation from a low-pressure Hg lamp is emitted in resonance lines at 254 nm and 185 nm, the 254-nm line being typically 4 to 10 times2 (1) This work has been supported in part by the U. S. Atomic Energy Commission under Contract AT(l1-1)-1715 and by the W. F. Vilas Trust of the University of Wisconsin. (2) B. T. Barnes, J . App. Phys., 31, 862 (1960).
NOTES
4291
-I
5
1.0
n 0
0
1.0 2 .o FLOW RATE,
3.0
4.0
P MIN-I
Figure 2. Optical density of 1 cm OA-0,layer as a function of flow rate through ozonizer and irradiation tube C (Figure 1). Figure 1. Arrangement for photolysis at 185 nm using flowing O1filter.
the intensity of the 1S5-nm line. For many photochemical studies with the 1S5-nm line it is necessary to filter out the 254-nm radiation. X- or y-irradiated IiF,3 interference filter^,^ and cyclohexane solutions of 9,lOdirn~thylanthracene~ have been used for this purpose. All are inconvenient to produce and maintain. Using flowing O2 containing a few per cent O3 as a filter for a helical low-pressure mercury lamp (Figure l), we have obtained higher 185 nm/254 nm ratios at high 185-nm intensities than previously available. The 03-02 mixture made by flowing 0% through a bank of 5 silent discharge tubes6 passes through a flow meter (A) and a 28mm i d . Suprasil tube (C) positioned in the center of a lamp (B) of the type described by Lossing.' Sample tubes (D), up to 9 mm o.d., can be inserted into C for irradiation while surrounded by a flowing 03-O2 layer ca. 1 cm thick. The extinction coefficients of O3 reported in the literature are 2.95 X loa mol-' cm-* a t 254 nman and 3 X lo2mol-' cm-l at 1'85 nm.8b Consistent with these values our measurements indicate a value at least tenfold higher at 254 nm than that at 185 nm. Tests of the efficiencyof the 08-02 filter by HI and HBr actinometry* in Suprasil tubes (which transmit both 254 nm and 1S5 nm) and Vycor tubes (which do not transmit below 210 nm) indicate a 4 to 1 ratio of 254 nm to 185 nm entering the sample without the filter aud0.00S to 1with the filter. Under the conditionsused, the O3filter absorbs 99.9% of the 254-nm radiation and transmits about 50y0 of that at 185 nm. Four cc of HBr at 200 Torr in the 7-mm id., 10 cm long tube positioned inside the helical lamp absorbed 1 X 10l6photons sec-I cc-l (nearly 100% of the incident light) during operation of the filter. For comparison, a Hanovia SC2537 lamp with a 25-mm diameter window operated by a 5-kV ballast transformer at a current of 100 mA yields about lolaphotons sec-I entering the 2-cm diameter face of a cylindrical reaction cell through a -pimadiated LiF filter with a lamp to cell distance of 1.5 cm. The optimum steady-state concentration of Oa in the
filter during illumination is obtained at a flow rate of ca. 0.7 1 min-' (Figure 2). At lower rates decomposition of Oa by the 254-nm radiation'0 controls the effluent concentration, while at higher rates it is controlled by the decreased efficiencyof production in passing through the ozonizer. The effluent Op concentrations were measured spectrophotometrically in optical cells. The Oa-02 effluent from the filter is vented to the hood or the Oa is destroyed by bubbling through aqueous KI to avoid a health hazard. (3) J. L. Weeks, S.Gordon. and G. M. Meaburn. Ndurc, 191, 1186 (1961). (4) D. Schroder. J . Opt. Soc. Amer., 52, 1380 (1962). (5) C. M. Wok7 and R. Pertel. W.. 54, 1168 (1964). (6) A. C. Jenkins, Advan. Chem. Ser.. 21 (1959). (7) F. P. Lossing. D. G. Marsden, and J. B. Farmer, Con.J . Chcm.. 34, 701 (1956). (8) fa) M. Greggs. J . C h m . Phys.. 49. 857 (1968); (b) Y. Tanaka. E. C. Y. Inn. and K. Watanabe, W., 21. 1651 (1953). (9) For referenoes see: (a) R. Fass, J . Phya. Chcm., 74, 984 (1970); (b) K.Martin and J. E. Willard. J . Chem, Phya., 40,2999 (1964). (IO) L. T. N. Jones and R. P. Wayne. W.. 51.3617 (1969)
Measurement of Thermal Diffusion Factors by Thermal Field-Flow Fractionation by J. Calvin Giddings,: Margo Eikelberger Hovingh, and Gary H. Thompson Deparlment of Chemislry. Univcrdy of Ufolr. Solt Lake City. Utah 84218 (Received July 20, 2070)
The degree of retention of solute peaks in gwliquid partition chromatography (glpc) is directly dependent on the liquid-gas distribution ratio. I n recent years glpc has been increasingly "inverted" in function to obtain meaningful partition coefficients from retention data.' This method is noted for its speed, accuracy,
* To whom oorrespondenee should be addr-d. (1)
J. C. Giddings and K . L. Mallik, I d .Eng. Chern., 59, 17 (1967). The Journal of P h y d Chaniatw, Vol. 74,No. 84.1970
