f
n = number of experimental points x,_y = concentrations x- = arithmetic mean of x values y = arithmetic mean of y values LITERATURE CITED
WEIGHT
%
ACID
IN
AQUEOUS
PHASE
Figure 1. Distribution of acetic acid between water and methyl isobutyl ketone a t 28 C. (system AO-14, reference 27)
experiments is greater than the individual error in either slope. The use of linearized data is not suitable for every purpose. When careful design is required, it is best to fit curves of higher orders and to do the arithmetic on a computer. This is particularly true when one is interested in nonlinear portions of the equilibrium curve. An error of only 1% in the linearization of the data may lead to as much as say 10% error in the design. Finally, isothermal conditions of operation are implied, and this may not always be so, especially in the case of gas absorption. NOMENCLATURE
b = slope of line passing through F , m = slope of line passing through origin
Asselin, G.F., Comings, E.W., Ind. Eng. Chem. 42, 1198 (1950). Azamoosh, A,, McKetta, J.J., J. CHEM.ENG. DATA4; 211 (1959). Bak, E., Geankoplis, C.J., CHEM. ENG. DATA SER.3, 256 (1958). Bodansky, M., Meigs, A.V., J . Phys. Chem. 36, 814 (1936). Briggs, S.W., Comings, E.W., Ind. Eng. Chem. 35, 411 (1943). Colburn, A.P., Tmns. A m . Inst. Chem. Engrs. 35, 211 (1939). Davies, O.L., “Statistical Methods in Research and Production,” 3rd ed., pp. 173-4, Oliver and Boyd, Edinburgh, 1957. Elgin, J.C., and Browing, F.M., Trans. Am. Inst. Chem. Engrs. 31, 639 (1935). Fowler, R.T., Noble, R.A.S., J . Appl. Chem. 4 , 546 (1954). Hartland, S., Mecklenburgh, J.C., Chem. Eng. Sci. 21, 1209 (1966). Horiuti, J., Sci. Papers, Inst. Phys. Chem. Res. (Tokyo) 17, 125 (1931). Klinkenberg, A., Chem. Eng. Sci.1, 86 (1951). Kremser, A,, Natl. Petrol. News.22, 42 (1930). Lindley, D.V., Suppl. J . Roy. Statist. SOC.9, 218 (1947). Murty, N.S., Subrahmanyam, V., Murty, P.D., J. CHEM. ENG. DATA1 1 , 335 (1966). Neuhausen, B.S., Patrick, W.A., J . Phys. Chem. 25,653 (1921). Othmer, D.F., White, R.E., Trueger, E., Ind. Eng. Chem. 33, 1240 (1941). Petrits, V.E., Geankoplis, C.J., J. CHEM.E N G . DATA4, 197 (1959). Rao, M.R., Murty, P.D., J. CHEM.ENG.DATA10, 248 (1965). Sander, W., 2. Physik. Chem. 78, 513 (1911). Scheibel, E.G., Karr, A.E., Ind. Eng. Chem. 42, 1048 (1950). Sims, L.L., Bolme, D.W., J. CHEM. ENG. DATA10, 111 (1965). Smith, H.W., J . Phys. Chem. 25, 160 (1921). Smoot, L.D., Babb, A.L., Ind. E r g Chem. Fundamentals 1, 93 (1962). Vermijs, V.J.A., Kramers, H., Chem. Eng. Sei.3, 56 (1954). Williams, K.C., Ellis, S.R.M., J . A p p l . Chem. 11, 492 (1961).
RECEIVED for review June 5, 1967. Accepted February 23, 1968.
Adsorption of Ferripolyphosphate SISTER MARY KIERAN McELROY,’ J. FRED HAZEL, and WALLACE M. McNABB University of Pennsylvania, Philadelphia, Pa. 19104
A
EXPERIMENTAL PROCEDURES
’ Present
Preparation. The preparation of these porous white gels has been reported (4, 6). They were obtained by the addition of solutions of sodium polyphosphate glass (30.5 grams of R-S unadjusted Calgon in 100 ml. of water), having the general formula Nan . ?P,Ol, - and an average of nine phosphorus atoms per chain, t o 0.5M iron (111) salt solutions. The gels were desiccated by washings with dioxane before drying in an oven. Analysis of the gels gave a molar Fe201-PLOjratio of 0.41. This ratio is equivalent to the
SUBSTANCE which possesses a surface of 100 to 1000 sq. meters per gram is considered a high-grade adsorber. The authors have prepared iron polyphosphate gels belonging to this class of absorbers. Their high capacity for basic materials, such as water and ammonia, and especially their low regeneration temperature should make them of interest where low heat with relatively high drying efficiency must be maintained.
3 64
address: Chestnut Hill College, Philadelphia. Pa.
19118
JOURNAL OF CHEMICAL AND ENGINEERING DATA
The cycling performance of ferripolyphosphate gels for water adsorbed at room temperature from 18 and 3 1 O h relative humidity has been studied at a constant regeneration pressure of 0.1 a h . and temperatures of 4 5 O , 65', and 120'C. The amount of water adsorbed by gels regenerated at 120OC. was about 50% greater than gels regenerated at 45'C.; while the percentage of water desorbed at 12O'C. was about 100% greater than that desorbed a t 45OC. The capacity of the gels for ammonia adsorption increased with aging.
substitution of an iron (111) atom for three sodium atoms in the phosphate chain (NaeO-PzOj molar ratio 1.22, empirical formula NaIIPYO2+) to give the empirical formula F e 1 8 P ? - O h , . n H ?The 0 . value of n varies with the drying procedures. Adsorption. Water was adsorbed in a static system a t room temperature ( 2 ) (22-25" C . ) . Samples were placed in small weighing bottles in a desiccator containing a saturated solution of CaCl? (315; relative humidity), or K C A O ? (18.7''; relative humidity) for a 12-hour period. After adsorption, the samples were removed from the humidity atmosphere, weighed, and desorbed in a heated vacuum desiccator. T o study ammonia adsorption volumetrically, a modified nitrometer was constructed from a 50-ml. buret (7). I n some runs, the amount of NHI adsorbed on the sample was also determined by the Kjeldahl method ( 5 ) .
Table I. Cycling Performance of Ferripolyphosphate for Water Adsorption 1 8 ' ~R H
Cycle 'I
1
2 :3
4 5 6
A
D
18.0 10.1 8.4 8.9 7.8 7.8 8.4 10.1 8.9 8.4 18.9 10.6 12.9 15.2 14.3 18.9
10.1 8.4 8.4 7.8 7.3 8.4
31'c RH
'CD 56.1 46.7 46.7 42.2 39.5 44.2
A
D
20.2 11.3 9.9 10.3 9.4 8.9 9.4 11.3 9.1 9.9 20.7 12.4 14.5 16.1 16.6 21.8 19.7 22.8 10.9 18.1 23.9 25.7 30.9 32.8 34.7 36.1 32.3 36.6 33.8 31.4
11.8 9.4 9.9 9.4 8.0 9.4 8.9 11.8 9.4 11.3 145 10.9 16.1 17.1 21.2 19.2 19.7 15.5 11.9 17.6 2
