1272
INDUSTRIAL AND ENGINEERING CHEMISTRY
----
I d
toL
___-
----
I
100 % OF THEORETICAL
~
I 2 3 4 REOEHERATION LEVEL LEOUIVALENTS HISO.
Figure 11.
5 PER LITER)
Regeneration of Amberlite
IRC-50 with Sulfuric Acid
acid cation exchange resins are readily explained on an acid strength basis. Since the carboxylic group of Ainberlite IRC-50 forms a weak acid, the hydrogen ion has a strong affinity for tho oxygen of this group and is very difficult t o replace. On the other hand, since most other ions form strong electrolytes with the carboxyl group, the hydrogen ion is able t o replace these cations very readily. The differences observed in the sodium-calcium and sodiummagnesium exchange equilibria for the carboxylic and sulfonic acid exchangerq are similar to the behavior of soluble sulfonic and carboxylic acid electrolytes. The polybasic carboxylic acids exhibit a sequestering ability for the dibasic alkaline earth cations whereas the corresponding salts of sulfonic acids are true strong electrolytes. apparently this property of the carboxyl group carries over to the resinous carboxyl cation exchangers and may account for the unusual ability of Amberlite IRC-50 t o adsorb calcium ions in preference to the sodium ion. A41though this property of the carboxyl exchanger, Amberlite IRC-50, enables the resin to soften water efficiently in the presence of a large excess of sodium salt, the equilibrium is such t h a t regeneration with brine 1s highly inefficient. -4lthough the rate data were rather meager, the fact t h a t in the hydrogen cycle the rate decreased as the acidity of the functional group decreased and the fact that in the sodium cycle the rates of both the carboxylic and sulfonic type resins are comparable are highly significant. These results indicate that the rate of exchange is dependent upon the degree of dissociation of the cation exchange micelle Since a swelling of the resin gel structure accompanies the transition of the weak electrolyte form of the resin to the strong electrolyte form, the increased rate of cxchange may be attributed t o a n increased rate of diffusion. The column performance of Amberlite IRC-50 in both the
Vol. 41, No. 6
sodium and hydrogen cycles is consistent, with the equilibrium and rate data. I n the sodium cycle, the resin is capable of adsorbing most cations which in turn may readily be eluted with a minimum of acid. I n the hydrogen cycle, the resin is capable only of adsorbing cations present as hydroxides, carbonates, bicarbonates, or as salts (borates and silicates) whose corresponding acids are not sufficiently acid t o cause the p H to drop below p H 4 to 5 during the exhaustion. As the p H drops below 4.0, the competitive activity of the hydrogen ions is such that only hydrogen ions are adsorbed. The chief advantages of a carboxylic cation exchanger over a sulfonic acid exchanger depend upon the application. For the removal and recovery of cations of alkalies, carbonates, bicarbonates, silicates, borat'es, etc., the carboxylic exchanger will function as well as a sulfonic acid exchanger and may be fully regenerated much more efficiently with acid than the strongly acidic sulfonic acid exchangers. The carboxylic cation exchanger permits one to remove the undesirable calcium bicarbonat,e in waters without the formation of mineral acids from the sulfate and chloride salts. This application is of considerable interest t,o the beverage industry. The carboxylic exchanger may also be used for deionization purposes in conjunction with other exchangers. If a dilute solution is passed through a strong base anion exchanger in the hydroxyl form ( 3 ) , the salts will be converted t o their corresponding hydroxides which may then be removed by the carboxylic exchanger. For the conventional scheme of deionization, the use of the carboxylic exchanger before the sulfonic acid exchanger enables one to deionize m t e r s cont'aining bicarbonates more economically since carboxylic exchangers may be more efficiently regenerated with sulfuric acid and will not be hindered by the calcium sulfate precipitation t h a t markedly reduces t,he capacit.y of sulfonic acid exchangers. I n essence, the carboxylic cation exchanger serves as a solid buffer for exchange reactions in a manner analogous t o soluble weak acids and their salts in homogeneous solution reactions. LITERATURE CITED
(1) Davidson, G. F.,and Nevell, T. P., J . TestiZeInst., 39, T59 (1948). (2) Griessbach, R., Beiheft Z . V e l . deut. Chem. 31, Angew. Chem., 52, 215-19 (1939). ( 3 ) Kunin, It., and McGarvey, F. X., IKD.ENG.CHEX.,41, 1265 (1949). (4) Kunin, R.,and Meyers, R. J., J . Am. Chem. Soc.. 69, 2874 (1947). ( 5 ) Mattson, S., Ann. AQT.Coll. Sweden, 10, 56 (1942). (6) Myers, R. J., Advances in CoZZoidSci., 1, 317-51 (1942). (7) Wieland, T., Be?., 77, 539 (1944). (8) TViklander, L., Ann. Rog. Aor. Coll. Sweden, 14, 1 (1946). (9) Winters, J. C., and Kunin, R., IND. ESG.CHEX, 41, 460 (1949). RECEIVED September 10, 1948. Presented before the Division of Industrial and Engineering Chemietry at the 114th hIeeting of the AYERICANCHEYIC A L Socmry, JVashington, D. C.
Volumetric Behavior of Benzene J. W. GLANVILLE .AND B. H. SAGE California Institute of Technology, Pasadena, Calif'. T h e specific volume of benzene was determined at seven temperatures lying between 100' and 460' F. and for pressures between vapor pressure and 10,000 pounds per square inch. The results are presented in tabular form.
T""
,vapor pressure, critical constants, and volume of benzenc as saturated liquid and saturat>edgas were determined by Young (9). This work was supplemented by later investigations o f the vapor pressure at relatively low temperatures ( 7 , 8).
The influence of pressure and temperature upon the volume and refractive indcx of this compound was studied by Gibson and Kincaid ( 3 ) . Limited inforination concerning the heat capacity mas obtained by Burlew (2). Gillilarid and Lukes ( 4 ) measured directly the effect of pressure upon the enthalpy of benzene. These investigations serve to establish the volumetric behavior a t low pressures. It would be possible t o calculate the specific volume at higher pressures from the enthalpy-pressure measurements of Gillilund and Lukes if volumetric data were available
as measured in a glass pycnometer was 0.01861 cubic foot per pound.
VOLUME OF BENZENE TABLE I. SPECIFIC ~~
+sye,
100
O F .
160a F.
Specific Volume, Cu. Ft./Lb. 280' F. 340° F ,
400" F.
480" F.
(126.00) 2
(222.06) 0.02441
(363.46) 0.02704
.....
,....
220° F.
EXPERIMENTAL RESULTS
Lo./Uq.
In. Ab*. Bubble point
1273
INDUSTRIAL AND ENGINEERING CHEMISTRY
June 1949
(3.21)a
(11.08)
(29.15) o,02028
(64.68)
-
The specific volume of benzene was determined at seven temperatures between 0.02258 100" and 460' F. The values, which were 0,02252 0:oiiiz 0.02422 0.02693 0,02246 obtained a t irregular pressures, were 0.02412 0.02665 0,02241 0.02640 0.02 402 0.02235 smoothed graphically to even pressures n n3 ,.,-382 0.02598 0.02224 1!.02365 0.02562 0.02214 and the results are recorded in Table I. ^"343 0,02526 U.UB 0,0220u 0.02494 The values of the two-phase pressure given 0.02325 0.02188 0.02307 0.02466 0.02178 in Table I represent critically chosen values 0.02290 0.02442 0.02165 275 0.02420 0.02155 based upon recent measurements of Hixson ,.,,260 0.02400 0.0214c 0.02136 0.02247 0.02381 et al. ( 5 ) and the earlier data of Young 0.02234 0.02362 0.02128 0.02211 191 0.02330 0.02300 (9). The agreement between the two ex0,02113 0,02099 0.02 perimenters was sat.isfactox-y and no effort n_.._172 nz 0,02274 0,0208F. 0.02155 0.02250 0.02071 was made in the present investigation to 0,02125 0.02210 0.02048 0.02025 0.02098 0.02177 determine the vapor pressure. 0.02076 0.02147 0.020015 0,02055 0.02121 Table I1 presents a comparison of the 0.01988 0.01973. 0.02,035 0.02098 specific volumes a t bubble point as sQuare incn aosoiute. measured by Young ( 9 ) with those obtained in this study. The data of Young were interpolated in order to obtain values of the specific volume at states corresponding to for one temperature throughout the range of pressures. Howthosf: reported in Table I. The average deviation of the present ever, at the lower reduced telnperatures and higher pressures results from those of Young was 0.3% and similar deviations were there does not appear to be adequate volumetric information also found with more recent data ( 4 ) . The present measurements for the purpose. For this reason a study was madc of the inwhich were carried out in stainless steel apparatus over mercury fluence of pressure and temperature upon the volume of benzene agree within 0.05% with t'he independently determined values of at seven temperatures lying between 100" and 460" F. and for specific volume of the liquid obtained with a glass pycnometer a t pressures between vapor pressure and 10,000 pounds per square 100O F. and atmospheric pressure. inch. ^ ^ _ ^ "
U.vYl3J 0.01943 O.O'l862 0.02131 0.02026 0.01941 0.01859 0.~1940 0.02024 0.02127 0.01858 0.02123 0,01857 0,01938 0.02021 0,01936 0,02018 0,02118 0.01856 0.02114 0.02015 0.01935 0.01855 0.02110 0.02013 A.~~ 00 0.01864 0.01932 0.02102 0,01928 0.02008 0.01851 800 0.02095 0,01924 0.02003 1,000 0.01849 0,01997 0,02087 0.01920 1,250 0.01845 0,01992 0.02080 0.01915 0.01842 1,500 0,01987 0,02073 1,750 0,01839 0.01910 0.02065 0,01981 0.01906 0.01836 2,000 0,02058 0.01976 0.01902 0.01832 2,250 0.02052 0.01970 0.01897 0,01829 2,500 0,02045 0.01965 0.01893 2,750 0.01826 0.02039 0.01961 0.01889 3,000 0.01823 0.01952 0,02027 3,500 0,01816 0.01881 0.02015 0,01874 0.01942 4,000 0.01810 0.02003 0.01932 0,01804 0.01867 4,500 0.01992 5,000 0,01799 0,01860 0.01923 0,01974 0.01907 0.01848 0.01790 6,000 0.01957 7,000 0,01783 0,01837 0.01895 0,01882 0.01940 0.01826 0.01776 8,000 0.0192h 0.01869 9,000 0,01767 0.01814 0,01804 0,01856 0.01911 10,000 0.01758 :r 0 Figures in parentheses are vapor pressures in pounds Pc
100 200 300 400 500
,,_A"
U . UZLD
..... . . ... . I . . .
,. ~
.,
METHOD AND EQUIPMENT
The apparatus used in this investigation has been described (6). I n principle it consists of a stainless steel container, the effective volume of which is varied by the introduction or withdrawal of mercury. The chamber is located in an oil bath, the temperature of which was controlled automatically within 0.02" F. of the desired value, relative to the international platinum scale. The pressure is determined by a balance calibrated against the vapor pressure of carbon dioxide a t the ice point ( 1 ) . The samples of benzene are introduced into the apparatus utilizing weighing bomb methods that have been described (6). After introducing the benzene the temperature of the oil bath is adjusted t o the desired value and the pressure increased to about 10,000 pounds per square inch, After the volume of the system occupied by the sample is determined (6),the pressure is decreased and the volume again determined. This process is repeated until the entire pressure range is covered. The temperature is then changed and another set of measurements is obtained.
~~
~
TABLE 11. SPECIFICVOLUME A T BUBBLE POINT Temperature, F. 100 160
220 280 340 400 460
Pressure, Lb. / S q , I n . ribs. 3.2 11.1 29.2 64.7 126.0 222.1 363.5
Specific Volume rluthors Young ( 5 ) 0.01862 0.01862 0.01943 0.01943 0.02028 0,02028 0.02133 0.02144 0.02262 0.02278 0.02441 0.02453 0.02704 0.02716
'j& Deviation
0.0 0.0 0.0 0.6 0.7 0.5 0.4
ACKNOWLEDGMENT
This w-ork was carried out as a part of the activities of a Polymerization Process Corporation fellowship which made the study possible. 13. H. Reamer supervised the details of the laboratory work and W. N. Lacey assisted in the preparation of the manuscript.
MATERIALS
The benzene used in this investigation was obtained commercially as the chemically pure grade and was subjected t o the following purification procedure. The sample was first distilled from a glass fractionating column containing 30 plates a t a reflux ratio of approximately 40 t o 1. The initial and final quarters of the sample mere discarded. The benzene was solidified and allowed t o melt partially, and the material first melted was discarded. The remaining solid material was then distilled under high vacuum into a glass container and condensed as a solid. I t was transferred by distillation into a steel weighing bomb. The index of refraction for the D line of sodium at 77" F. was 1.5013. The specific volume at 100' F. and atmospheric pressure
LITERATURE CITED
Bridgeman, J . Am. Chem. Soc., 49, 1174 (1927). Burlew, Ibid., 62, 681 (1940). Gibson and Kincaid, Ibid., 60, 511 (1938). Gilliland and Lukes, IND.ENG.CHEM.,32, 957 (1940). Gornowski, Amick,and Hixson, $bid., 39, 1348 (1947). (6) Sage and Lacey, T r a n s . Am. I n s t . M i n i n g Met. Engra., 136, 136.
(1) (2) (3) (4) (5)
(1940).
(7) Smith, J . Research NutZ. B u r . Standards, 26, 129 (1941). (8) Smith and Matheson, Ibid., 20, 641 (1938). (9) Young, Sci. Proc. Roy. Dublin SOC.,12, 374 (1910). RSOBIVED May 14, 1948.
