October, 1944
INDUSTRIAL AND ENGINEERING CHEMISTRY
895
mount,ed on a steel and wood support spring sensitivity of 241.86 mm. The adsorption equilibria of pressures, temand cushioned with sponge rubber to per gram, weight changes of peratures, and concentrations on a comabout 0.000004 gram could be measminimize vibration. mercial activated carbon were determined ADSORPTIONTUBE A . This vertical ured. tube, about 90 cm. long, contained VAPORPRESSURE TUBEH . The for the following organic solvents: acetone, organic liquid entered this tube weighing spring Q, the carbon, and methyl ethyl ketone, methyl isobutyl via buret G and cock H and was 'two thermometers, Tc and TI,for ketone, methanol, carbon disulfide, and maintained at the desired temperaethyl ether. A n improved apparatus R measuring their respective temperai ture by the constant-temperature tures. A quartz fiber, Ti, supported described which permits rapid measurebath in a Dewar flask, N . Temperaluminum bucket U and the carbon. ment of the equilibrium adsorbate conAt the top of this tube was a hollow atures below room were used, since centration over wide ranges of vapor presabove that point there was conground-glass stopper J into which had sure and adsorbent temperature. The apdensation within the system. A beensealedtwo I-mm. glass cross bars. paratus is of the static weight type in which The tandem thermometers were sussolid carbon dioxide-methanol soluthe weight of vapor adsorbed is measured by tion was used as a bath and was pended by a hook from one of the observing with a microscope the elongation thoroughly mixed by an electricross bars and the spring-bucket of a sensitive beryllium copper spring carrycally driven stirrer (not shownj. system from the other. When ing the adsorbent. The data are plotted The additions of the solid carbon chis stopper was raised, therefore, initially as isotherms; from these the isodioxide were small and frequent: everything in the tube was resteres are cross-plotted to give straight-line and the temperature was readily moved. relations by the graphical method premaintained within 0.5" C., as shown The lower thermometer, T I , had viously described (13). Heats of adsorption by thermometer Ts. E nominal range to 550" C. in are calculated by the same method. Such hfANOblETER Connected to order to withstand the high Lemdata of adsorbent characteristics and vapor the top of vapor pressure tube perat,ure of the degassing operation, adsorbability over the wide ranges studied B was a n open-end, U-bend, 7-mm. later described. It was read during are important as the basis for industrial Pyrex manometer, filled with triplethe runs (as well as thermometer design and applications in solvent recovery distilled mercury. The end open Tt in the bath outside of the adoperations."The photograph shows an a t the atmosphere passed down sorption tube) and recalibrated after instrument panel and adsorbers in a cominto a small bottle stoppered with each run. Corrections were made pletely automatic Columbia activated carclean cotton; and a steel scale later to values read. This was necbon solvent-recovery plant (courtesy of allowed measurements which could essary because of the tendency Carbide & Carbon Chemicals Corporation). be estimated to 0.1 mm. to give a different reading after' exCONSTANT-TEMPERATURE BATHS posure to the high temperature of deL AND l v AND COLD T R 4 P D. sassine. Dewar flask L contained a mixture of methanol and solid carbon BERYLLIUM COPPERSPRINGQ. The heart of the apparatus dioxide so that any diffusing mercury vapor would be condensed was weighing spring Q. The literature methods for fabricating while the pumps were operating during the purging of the quartz springs (2, 8) were tried and found laborious. A semicarbon. The entering line to the vacuum system was 22 mm. automatic machine was constructed so that satisfactory springs in diameter, and a 42-mm. jacket served as a condenser. Transcould be fabricated with a minimum of difficulty. They are, parent Dewar flask M contained peanut oil, an electric agitator, however, very fragile, and it seemed desirable to find a better and an immersion heater. A Variac transformer allowed temmaterial. perature control within 0.5' C. Thermometer TPserved to check Beryllium copper combines exceptional strength with corinternal thermometer TI. rosion resistance, high endurance strength, and heat hardening PUMPS E AND F. The vacuum pump system consisted of a after forming, and therefore approaches most closely the ideal Cenco mercury diffusion pump and a Cenco Pressovac-with the metal for springs (6). The final spring was made of this alloy necessary accessories to reduce the pressure to 10-6 mm. merby Instrument Specialties Company, Inc., and was calibrated cury. by adding standard weights to a small mica pan suspended from STOPCOCXS 0,K , AND H . Vent cock 0 was a standard 2-mm. the lower end. A perfect straight-line relation was found throughbore vacuum cock. A large 10-mm.-bore vacuum cock, K , with out the entire range of elongation us. weight. Details of the spring follow : mercury seal closed off the pumps. Liquid supply cock H had a capillary bore, mercury seal, and pressure-equalizing connection to the base. The most satisfactory stopcock grease for acetone Outaide diam mm. 8 28 Sensitivity, mm. 241.86 Dirm. of wire: mm. (in.) 0:178 Compressed len& mm. 69 and methanol was Apieeon M (Shell Oil Company); and that (0.007) Suspended free lenith, mm. 257 No. of turns 301 most resistant to methyl ethyl ketone, methyl isobutyl ketone, ethyl ether, and carbon disulfide was Nonaq (Eimerand Amend). MATERIALS.A commercial activated carbon from coconut BUCKETU. A piece of aluminum foil approximately 2.5 cm. shells was used; it was Columbia grade 4SXA, GSmesh (Carbide square was formed around a piece of 7-mm. glass rod. Two hoops & Carbon Chemicals Corporation). It was in the form of small of extremely fine wire and a thin bail were added. The final cylinders and had the following standard commercial specificabucket was 17 mm. long and 8.2 mm. in diameter and weighed tions and screen analysis: 0.0427 gram. I t was suspended from the spring by a long (65-cm.)link, V , of fine quartz fiber, to keep the spring above the Speoifioations Screen Analysia, % heated base of the adsorption tube A . Activity, % 85.5 4-8 mesh 2.6 CATHETOM~TER P . This was mounted on a %inch steel pipe Retentivity, %, 43.8 6-8 mesh 87.3 Apparent density 0.462 8-10 mesh 7.2 connected to a */*-inch steel plate which was bolted onto the Strength 7 96 10-14 mesh 2.4 Ash, t o t & 9/, 1.15 FlnW 0.6 stone desk top. I t had a focal range of about 2 inches and was focused on the lowermost coil of the spring which was illuminated The liquids were C.P. materials, further purified and distilled by a blue microscope light, R, from behind. The range of verin an efficient laboratory rectifying column, with a discard of tical motion was 50 mm.; the vernier scale was read directly fractions above and below ttheaccepted boiling points. to 0.005 mm. and could be interpolated to 0.001 mm. With a
e.
- -
896
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
Vel. 36, No. 10
10 - 6 mm. During this time the charcwalwas maintained a t 500" C. and thus degassed. Large stopcock K was closed. mercury diffusion pump E and Pressovac pump F wei'c shut off, and furnace TI' was shut down gradually so thar t,he final at,ta,iiiment of room temperature took several L hours . PI-RGING.The next day 2 ml. of liquid were passed lowly through stopcock H . This vaporized immediate1)anti \vas adsorbed by the carbon with consequen elongation of t,he spring. Gas molecules, not removed by thc, first degassing, were supplanted oil the carbon surface b!. P molecules of t,he substance to be studied. An exact repetition of the degassing operation served to put the carbon in final condition. The new length of the spring was then rioted; this became the zero point. I).irra TAKING.Wit,h the carbon completely degassed. SPI 1 1 the system was ready for use. Fifteen milliliters of liquid ivrre poured into buret G. Approximately 12 ml. wew lowly passed into vapor pressure tube B around whicli had been placed a solid carbon dioxide-methanol -./7 bath N , with a temperature of -77" C. Thi. condensed most of the flash vapor formed anti decreased the surge of adsorption on the cwboii. The temperature of this bath was allowed to risc Figure 1. Diagram of 4pparatus to give the desiretl vapor pressure of the liquid. Adsorption tulle containing weighing bpriiig " 3 sieiii -4. as shown by marionieter C. This temperatwe B . Vapor pressure tube containing, liquid being adsorbed Mercury manometer for nieasuring V H ~ pressure O ~ of liquid being ailsurhed iequililirium C. was maintained. E;lectiic furnace W was readsorption pressure) placed by constant-temperature oil bath M, anti D. Cold trap for condensing mercury vapor. E . llercury diffusion punip t o maintain 10 -6 mn,.H g pressure the desired carbon temperature was obtained antl F. backing pump (Pressovac) G. Graduated buret for supplying liquid t o systetii maintained. H . Capillary stopcock, mercury-sealed The weight of .adsorbate per gram of adsorbent I. Connecting tube between adsorption tube arid vapor pressure tube J . .idsorption tube stopper (mercury-sealed) for removing spring systeni was calculated from the deflection of the spring K . I.arge mercury-sealed stopcock (tn-riim, bore) for shutting off pump b / stem aftel evacuation observed with the cathetomet,er 1'. With fixed L . Dewar flask for cold trap, filled n i t h low-temperature mixture vapor pressure of t,he liquid and temperature of Dewar flask for adsorption tube h a t h , maintained t o give desired car1)oii teniper:rture .lf. .Y. Dewar flask for vapor pressure tube iiath, iuaintained t o give desired liquid temperat lie carbon, sorption was considered a t equilibriuni ture and vapor pressure $: Vent stopcock (2-mm. bore) when no change in length of the spring was obCathetometer for measuring elorigatioii of Upring qerved during a half hour. This equilibrium ronQ. Beryllium copper spring which elongates iis c.arbriti arkorbs ond ini.reaser i n neialit R . Mcroscope light clition was always attained within approximately ,A', Agitator for constant-temperature b a t h TI. Thermometer for measuring carbon temperature 2 hours after changing either the charcoal kniT ? . Thermometer for measuring temperature of bath around adsorptioti tube perature or the liquid temperature and vapor TI. Thermometer for measuring temperature of liquii! being vaporized and adso?iieil TA. Thermometer f o r measuring spriiig temperature pressure. U. Aluminum bucket for holding carhon as adsorbent V . Quartz fiber link t o suspend adsorhetit in heated zone, with spring itself sufficierirl\ During a series of runs the temperature of' removed t o be cold the liquid and hence the vapor pressure, at iV. Removable electric furnace for heating car1,on during degassing operntioii .Y. External heater for maintaining desired bath temperature shown by manomrter C, were maintained conY . Crow section of adsorption tulle Yysteni and surrounding constant-temperature bath
OPERATION
The apparatus was thoroughly boiled out PRE:P.IRATION. five times with the pure solvent to be studied. The plugs of the stopcocks \%ereremoved, cleaned, and greased. The weighing spring was recalibrated each time it was removed, although deviations from the initial calibration were allvays negligible. h p p i oximately 0.2 gram (seventeen pellets) of activated carbon was placed in the bucket. The spring, link, and bucket with carbon were hooked to stopper J and lowered into tube A along with thermometers T Iand T,. .in initial reading was then made of the spring length. DEGASSING.Oil backing pump F was started, and large stopcock K was opened slowly. Removable electric furnace TI' \\as mounted around the lower portion of adsorption tube A with the bucket in the center, and was heated slowly until thevmometer TI read 500" C. A shield of asbestos board, 6 inches above the furnace, prevented heating of the spring by radiation. lfter an hour of pumping, the pressure was approximately 0.01 mm. A solid carbon dioxide-methanol bath, L, was placed around mercury trap D to condense any mercury vapor. Then mercury diffusion pump E was started and allowed to p u m p for 6 hours to give a pressure of approximately
I
I
Equilibrium Vopu P r e s w e of Acetone (mm.)
Figure 2.
Isotherms of Acetone Adsorption
1
October, 1944 qtant; and the carbon temperature was changed from 40' to 200' C. in u n i f o r m s t e p s of 2 0 " . While a series was usually made with increasing temperatures of carbon, these ,cries were checked frequently by reversing the temperature steps andalso . i t intervals the same day. Once or twice check runs uere made after interniediate degassing. These tluplications confirmed the (lquilibria measured as being absolute and indicated t h a t t h e r e were n o m e a s u r a b l e hysteresis dects. Different series of runs were made for each of yevex a1 different liquid temperatures and vapor pressures. The upper limit of the liquid temperature was the room t e m p e r a t u r e , since, at higher liquid temperat ures, vapors condensed in the apparatus. Liquid temperatures below about -30" C. were not used b e c a u s e of t h e correYpondingly low v a p o r lxessures.
INDUSTRIAL AND ENGINEERING CHEMISTRY
897
TABLE I. ADSORPTIONOF SOLVENT VAPORS ON ACTIVATED CARBON Adsorbate Vapor Temp., pressure, ' C. mm.
- 70 - 32
-
5.8 7.4 21.8 31.1 44.8
-- 25 20
- 10 0 10 20 25 30
0.4 10 50.2 100 200 300 500 5.0 7.2 14.1 25.5 45.0 73.3 88.1 114.6
~
O'C.
20°C.
Adsorbate Conen., i n Grams/Gram Carbon, a t Carbon Temp. of: 40OC. 6 0 ° C . 8OOC. 100'C. 120OC. 14OOC. 160" C. 180" C. 200OC.
....
....
.... .... ....
....
0.5118 0.5257. 0.5511 0.5702
0.4340 0.4562 0.4948 0.5259 0,5551
,...
,...
0.3912 0.3264 0.4619 0.4060 . . . . 0.4390
.... .... ....
.... . ,.
.... ....
....
Acetone Vapor 0.0578 0.0366 0.0243 0.1920 0.1321 0.0905 0.3079 0 . 2 5 3 5 0.1942 0.3401 0.2971 0.2469 0.3650 0.3308 0.2885 0.3818 0.3526 0.3212 0.4017 0.3780 0.3512
0.0212 0.0635 0.1428 0.1941 0.2430 0.2781 0.3249
0.0202 0.0476 0.1050 0.1519 0.1979 0.2389 0.2941
0.3500 0.3990 0.4300 0,4519 0.4781 0,5070 0.5193 0.5381
M e t h j4 Ethyl Ketone 0.2980 0.2040 0.1470 0.3216 0.2467 0.1828 0 , 3 7 4 0 0.3120 0.2360 0.4073 0.3504 0.2870 0.4360 0.3840 0.3280 0.4540 0.4134 0.3672 . . . . 0.4365 0.4948 0.4603 o:iiiz
0.1065 0.1266 0.1760 0.2210 0.2600 0,3053 0.3250 0.3678
0.0715 0,0904 0.1270 0.1676 0.2060 0.2520
0.0984 0.2549 0.3540 0.3870 0.4100 0.4278
0.0177 0.0309 0.0780 0.1157 0.1551 0.1956 0.2509
0.0156 0.0278 0.0596 0.0882 0.1224 0.1552 0.2161
0.0135 0.0221 0.0494 0.0688 0.0968 0.1280 0.1830
0,0520 0,0653 0,0960 0.1262 0.1600 0.2000 . . . . 0.2210 0.3147 0.2580
0.0342 0.0467 0.0690 0.0960 0.1270 0.1598
o:iiio
0.0240 0.0360 0.0500 0.0711 0.0960 0.1300 0.1470 0.1818
0.1313 0.1680 0.1980 0.2290 0.2488
Akethyl Isobutyl Ketone Vapor -20 10
1.6 3.2 7.6 11.0 17.3
....
.... .I..
.... ....
.... ....
....
0.3420 0.3600 0,3725 0.3827 0.3880
0.1036 0.1317 0,1618 0,1940 0 2124
0.0792 0.1040 0.1300 0.1600 0,1771
0.0500 0.0764 0.1015 0.1300 0.1464
0 10
PO
7.6 29 98 54.7 95.1
.... .... .... ....
.... .... ....
Methanol Vapor 0.0301 0 0103 0 0082 0 0069 .... 0,0060 0.2373 0 0905 0 0357 0 0247 0'0205 0.0181 0.0171 0,3352 0 1693 0 0724 0 0380 0 0280 0.0229 0 . 0 2 0 5 0.4000 0 2558 0.1280 0 0600 0 0380 0.0301 0.0260
.. ., o:oibo ,...
0.0060 0.0105 0.0172 0.0180
-20 10 0 10 20
47.2 79.5 134.4 207.3 297.3
....
...* ....
Cnrbon 0.5580 0.4679 0.0002 0.5228 0.6397 0.5678 0.6595 0.5908 0.6741 0.6128
0.0738 0.1028 0.1414 0.1780 0.1938
- 20 - 10
64.0 123.6 208.8 290.8 458.8
....
-
0
10 20
- 20
-
0 10 20
.... ....
.. .. .. .. ... I
....
.... ....
....... .
....
.... .... .... .... .... ....
....
....
0.3481 0.3702 0.3879 0.3996 0.4000
RESULTS
Data are shown in Table I for the lower ketones (acetone, riiethyl ethyl ketone, methyl isobutyl ketone), and €or methanol, (,arbon disulfide, and ethyl ether. Isotherms (Figure 2) were plotted as adsorbate concentration us. equilibrium vapor pressures for all runs taken at the same carbon temperature. There %reas many points on each isotherm as there were different liquid temperatures and vapor pressures. These isotherms were then rross-plotted to give isosteres (Figure 3) by picking off the inter9ections of the isotherms with uniformly spaced ordinates. The method of plotting logarithms of equilibrium pressures us. logarithms of vapor pressures of a reference substance has been described ( I S ) . Acetone was chosen as the reference substance tor the plot of the ketones; it is the initial member of the ketone -cries, and available thermodynamic data for it are most complete. With the other materials, each was used as its own refertwce substance for plotting. The data points never deviated from straight lilies by more than the experimental error. Since there are no data for these On this carbon, no comparisons with other work can he made. The slopes of the lines were determined; hy the method previously indicated (IS), the iiijtantaneous or partial heats of adsorption were obt,ained and plotted (Figure 4). Vapor pressures of most of the liquids have not been reported in the literature for values below 0" C. (3,6,10, I J ) , and they arelisted in Table 11. Vapor pressures of the solvents studied are plotted in Figure 5 against the vapor pressure of acetone on log paper by t>he method previously described ( 1 2 ) .
0.3061 0.3281 0.3440 0.3594 0.3677
0.2608 0.2851 0.3128 0.3319 0.3451
Disulfide 0.3720 0.4280 0.4946 0.5312 0.5632
0.2193 0.1734 0.2419 0.2040 0.2760 0.2320 0,2994 0,2631 0.3160 0.2836
Vapor 0.2800 0.3608 0.4450 0,4770 0.5031
0.2085 0.2705 0.3422 0.3958 0.4345
0,1605 0,2070 0.2693 0.3180 0.3711
0.1187 0.1680 0,2174 0.2682 0,3076
0.0978 0.1265 0.1736 0.2150 0.2460
Diethyl Ether Vapor 0.2945 0.2497 0.2072 0.3300 '0.2945 0.2528 0.3557 0.3224 0.2831 0.3671 0.3331 0.2978 0.3736 0.3472 0.3186
0.1671 0.2123 0.2442 0.2620 0.2792
0.1243 0.1741 0.2095 0.2261 0.2496
0.0868 0.1379 0.1810 0.2005 0.2162
0.0641 0.1082 0.1552 0.1684 0.1817
,.
.,
.
,
.,
..
The lines are straight, and the calculated latent heats of vaporization agree with accepted values (5, 7 ) . The isotherms of acetone, methyl ethyl ketone, methyl ihobutyl ketone, carbon disulfide, and ethyl ether have the Sam? general shape. The rapid rise in the quantity of vapor adsorbed in the low-pressure region is marked at low carbon temperatures. This rate of increase flattens out with higher temperatures until the isotherms are almost straight lines. With increase of vapor pressure, the isotherms (especially those a t low temperatures) tend to become horizontal. I n this range a tremendous increase in vapor pressure gives only a small increase in adsorbate concentration on the carbon. This tapering off of the adsorption process infers that the initial forces which caused a great increase in the adsorbate concentration for a small pressure increase are now being diminished by interference of the adsorbed phaie, owing to a "saturation" effect on the carbon. In the case of methanol isotherms, instead of the initial steep
TABLE 11. AVERAGED VALUES FOR TEMPERATVRES AND VAPOR PRESSURES OF LIQUIDTAKEN AT CONSTANT TEMPERATURES OF LIQUIDAND DIFFERENT TEMPERATURES OF CARBON Temp., C. -30 -25 -20 -10 0 10 20 30
Acetone 10.8 15.2 21.4 38.0 69.0 114.5 184.5 282.5
Pressure, Mm. Hg Methyl Methyl ethyl isobutyl ketone ketone 3.3 ,. 5.0 7.2 i.6 14.1 3.2 26.5 7.6 45.0 11.0 73.3 17.3 114.6
..
__
__
Methaiiol
716 29:8 54.7 95.1
..
Ethyl Ether - Carbon Disulfide Temp., Pressure, Temp., Pressure. C. mm. H g O C. mni. l i y -20.5 54.5 -19.6 47.1 8.3 124.1 -10.0 79.5 2 . 2 208.8 1.1 134.2 9.9 290.9 11.0 207.3 20.6 460.0 20.0 297.2
+-
+
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
8398
L;i
IL
If
loo
/ 200 1
1
/
500
Temperature inCc.)
("C.)
Temperature
'
1''
io00
I
2000
9000
"01.
36, No.
la
Temperature i"C3
I
10000 Z o o 0 0
Vapor Pressure of Acetone imm3
TemDeroture la C.)
Vapor Pressure of Acetone
(mm.)
slope in the low-vapor-pressure region, there is a flat portion which bends upward at approximately 10 mm. pressure. This shape is observed mainly in the 40", 60°, and 80" C. isotherms, whereas those a t higher temperatures are practically straight lines a t small angles to the horizontal. This peculiarity had been observed previously ( I ) when water was the adsorbate. Because methano! closely resembles water, it may be expected to have somewhat similar adsorption properties. This peculiar behavior may be explained when it is realized that water and methanol, both highly polar, can collect on the carbon surface, not as single molecules, but as associated molecules (4) which interfere with normal adsorption. When the temperature is increased, the associated molecules are broken up, and adsorption proceeds normally. HEAT OF ADSORPTION
When vapors are adsorbed, heat is liberated in the range of one to two times the latent heat of condensation ( I S ) . When adsorption processes are used industrially for solvent recovzry, the liberated heat may be removed by cooling. The amount of cooling required to cool an adsorbent bed can be calculated readily from adsorption isost,eres. These values must be sup-
plemented by data concerning the effect of gas mixtures (carrier gas, etc.). The slopes of the isosteres (Figure 3) were measured and plotted against adsorbate concentration with temperature a8 the other parameter (Figure 4). These slopes are equal t o the ratio of the molar heats for the passage from the condensed to the gaseous phase of .the adsorbed material and of the reference. substance (is). The plots show that the differential heat of adsorption is usually affected by (a) the adsorbateconcentration, since different isosteres have different slopes, and ( b ) the temperature of the adsorbent, since latent heats always vary wit8h temperature. The first requirement for heat calculations is the latent heat of the reference substance over the desired temperature range, 0-200" C. These data for acetone are available up to 100" C. Higher values were calculated (22) from reduced temperature8 and pressures: Temp.,
c.
0 50 100 150 200
Latent Heat of Acetone, Cal./Gram Handbook value Calcd. ( 1 s ) 134.74 .... 126.5 121.7 112.76 1G9.6 _... 91.65 ... 64.0
INDUSTRIAL A N D ENGINEERING CHEMISTRY
October, 1944
893
Temperoture (“C.)
4001
’
I
I
~
.IO
I
Vapor Pressure of Reference Substance Carbon Tetrochloride in mm.Hg
MIK
.20
I
Figure 5. Vapor Pressure a t Low Temperatures of Compounds Studied
.
Adscfbote Cmentratim (p4.C)
Adsorbate Concentration (p/pC)
lower number, therefore, is the value of the partial heat of adsorption alone under these conditions. The change in isostere slope for the ketones runs in the following order: acetone, methyl ethyl ketone, methyl isobutyl ketone. The last substance evidently has no change in total instantaneous heat with change of concentration since it shows no appreciable change of isostere slope with adsorbate concentration. Other theoretical deductions from these data of the homologs of the ketone series and the substitute ethanes and methanes may also be made. Using the methods of this investigation, it should be possible to predict the adsorption concentration and heat data for homologs by extrapolation and interpolation from data measured Gn only a few systems of the series. The use of adsorption in refrigeration and air conditioning can be foreseen. The isotherms of a good refrigerant (liquid or adsorbate) in Adsorhte Concentrotion (g./g.C) Adsorbate Conoentration(g./g.C) an adsorption process should be widely spaced, very steep, and abrupt in the low-vapor-pres Figure 4. Instantaneous Heats of Adsorption of Solvent Vapors sure region. The greater the space between two particular isotherms, the more heat sensitive is the adsorbent, so that a lowering of a few Table I11 shows the adsorbate concentrations and instantandegrees will. give a great increase in adsorption. Conversely, it eous total and partial heats calculated at the various tempershould be possible to degas the adsorbent readily by increasing the temperature only a few degrees. The economics of the use of atures. Corresponding to each temperature and concentration are two numbers. The upper gives the total instantaneous heat adsorption in refrigeration and air conditioning will depend on of adsorption and condensation at these conditions; the lower is the selection of satisfactory vapors or gases as adsorbates and of obtained by subtracting the value of the usual latent heat. The satisfactory solids as adsorbents.
ci,
155
aa
, I
154 !I
hi !, I54 7
.vi 7
1.54
i:! i 154 1 52 I 154 2 52 ?
i.74
,
sL I
,55 !< i, !* 151 x
SI
x
15:i 6 i l 6
/
/
135 I, 47 2 i:i7 ti 4; I, ,:I7 7 I6 !I ,:I7 ,5 IG 7 l:L7 4 46 6 137 2 46 4 I:l7 I 18 :I ,:io !I 16 I 136 8 46 I, XI6 0 4s x
