9” - A ,,-—~""“‘ _,_.~.. .~ -1 PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. MAY BE RECALLED with earlier due date if requested. DATE DUE DATE DUE DATE DUE 6/01 c:/CIRC/DateDue.p65—p. 15 The Apparent Density Of Silica Gel Measured in Various Liquids Thesis Submitted to the Faculty of Michigan State College in Partial Fulfillment of the require- ments for the Degree of Master of Science. BY Reuben Warren Leisy Inna 1929 It has been definitely proven that such physical pr0perties of an adsorbent, as density, avail- able pore volume, and adsorptive power vary with the liquid employed. The variation in density or apparent dai- sity of activated carbon was studied by Harkins and Ewingl. Their conclusions were that the liquid at the surface of the carbon was compressed, giving a variat- ion in density relative to the compressibility of the liquid used and varying inversely as the surface ten- sion. Cude and Hulettz observed this same phen- omena, but interpreted it differently. They assumed in- complete penetration of the capillarys in the carbon and show that the densities obtained were proportional to the surface tension of the liquids employed and inversely pro- portional to their viscosities. They also observed that there appeared to be a leg or drift and that tha density measurements increased with time. Heward and Hulett3 attributed this increase to more complete penetration. The apparent density of silica gel has been measured in various liquids by several investigators, but the data is meager and the measurements have been.made far only a few liquids. Berle and Urban; studied the variation in density of silica gel when activated under varying cond- itions and also of quartz, using ether as the liquid 1023513 for their density determinations. Their choice of ether was based on the assumption that it would have a greater penetrating power than water. Nutting5 calculated the pressure necessary to produce these apparent densities in the case of water with silica gel by determining the heat of wetting on gels of various water contents. He plotted the water adsorbed as a function of the heat of wetting and computed the pressure. He found that when a layer of water, 100 mols thick, had been adsorbed there was a decided break in the curve and assumed this to be the limit of the range of adsorption. He gives a value of 17,410 atmospheres pressure for a layer 100 moles thick with a pressure gradient near the silica gel surface of 257 atmospheres per mol layer. In this work the apparent density of silica gel has been measured in 13 liquids in order that a compar- ison may be made with similar existing measurenents on activated carbon and also gain information as to the mag- nitude of the pressure necessary to prodme these abnormal densities. Apparatus The apparatus consists essentially in a high vacuum system for evacuating the tubes filled with gel. It is unique in that the vacuum.system.prOper is made en- tirely of pyrex ghass, has no stopcocks, and is sealed from the atmOSphere on one side by the mercury aolumn in the McLeod gage and on the Hyvac pump side by a mercury seal. Figure l is a detailed drawing of the apparat- us. Two Central blcientific Hyvac pumps are used, Pump No. l to pull the mercury out Of the McLeod gage (b) and con- trol the mercury seal (a); pump No. 2 as an exhausting pump to the atmosphere from the Langmuir mercury vapor pump which is in series with it. In sealing Off the vacuum.systen, stOp- cock (c) and (d) are Opened and the mercury rises in the two arms of the mercury seal (a) to barometric height from.the reservoir (6). Then stopcock.(d) is closed. To continue evacuating the system after it has been sealed, stopcodt (d) is Opened (c) closed and the mercury pulled from the mer- cury seal with pump No. l. Pulling the mercury down.until the seal is Open, but not to the stopcock. Now (d) is closed (0) opened to the atmosphere and the pump stopped. Stopcock (f) is used to Open the McLeod gage to vacuum pump NO. 1 ani the atmosphere. (3) is the Langmuir mercury vapar pump. (h) l, 2 and 3 are tubes filled with gel ready to evacuate. (i) is a calcium chloride tower to remove moisture from the air ent- ering the gage. (j) l, 2 and 3 are mercury traps. Iigure 2 is a detailed drawing of the tube used. C is an etched graduation on the stem to which the meniscus of the liquid under investigation is adjusted. The tubes have a capacity of approximately 25 cc. and will hold about 10 grams of gel. The side arm Of the tube is constricted at (b) in order to facilitate breaking dff file tip when immerced in the liquid. Figure I $35 3339 L b.— ——'D ”WA/w _ m L04~§>> NNQQOU ell. rl. Preparation of Materials (1) Mercury The mercury was aerated over night by bubbling air through it while covered with l : 3 nitric acid, passed thrua capillary into a column Of l : 3 nitric acid, through another capillary into a column of distilled water, dried with caustic soda, and then again passed through a capillary to remove the caustic soda. (2) ISOprOpyl Alcohol A commercial c.p. product. The iscpropyl alcohol was distilled from lime and then fractionmed. B.P. 79.70 - 79.80 738.9 mm. (3) Chloroform A commercial c.p. product. The chloroform was treated with concentrated sulphuric to remove the alcohol, washed with dilute sodium hydroxide and finally with water. It was dried over fused calcium chloride, followed by anhy- drous OOpper sulphate then fractionally distilled. B. P. 60.60 - 60.80 746.2 mm. (4) Carbon tetrachloride Product - Central Scientific c.p. The carbon tetrachloride was washed with water, sulphuric acii, water, sodium.hydroxide and finally water. It was then drhad over calcium chloride and fractionally distilled. B. P. 75.80 734.9 mm. (5) Carbondisulphide Product - Central Scientific CO. c.p. The same method Of purification was used as' for carbon tetra chloride. B. P. 44.50 747.5 mm. (6) Nitrobenzene Product - Central Scientific CO. c.p. The nitrobenzene was shaken with an equal volume of 10% solution of sodium silphite and stood in contact with the solution for 24 hours. The nitro- benzene was separated by use of a separatory funnel and washed with water. It was then.drt3d over calcium chloride and fractionally distilled. B.P. 209.9 — 210.20 744.6 mm. (7) Benzene Product - Wilkins Anderson CO., c.p. ThiOphene free. The benzene was treated with concentrated sul- phuric acid until a sample of acid did not darken on standing in contact with the benzene for a day. It was treated with sodium hydroxide to neutralize the acid wadi- ed with distilled water, dried over calcium chloride and fractionally distilled three times. The purified benzene was stored in glass stOppered bottles over metallic sndium. B.P. 77.9 "' 78° 738.6 (8) Pentane Product - Eastman Kodak Co. Practical No purification B. P. 27.40 740.1 mm. (9) Water Distilled water collected directly from the still which supplies the laboratories with water. (10) Petroleum Ether (Benzene) Product - baker Analyzed. B.P. 300 - 600 NO purification. (ll) Ethyl Alcohol The ethyl alcohol used was purifrad in this laboratory by Clark c. Sinclair(1). B. P. 77.60 740.1 mm. (12) Acetone Product - Wilkins and Anderson Co., c.p. The acetone was fractionally distilled and dried over calcium chloride. B.P. 55 .29’560 743.7 mm. (15) Ether Product - Wilkins and Anderson CO. c.p. over sodium. The ether was washed with water, then alkaline permanganate until there was no green coloration Of the 10 permanganate over a period of ten minutes and with water until free from alkali. The green coloration shows the presence Of alcohol. The purified prdiuct was dried over calcium chloride then.phosphorus pent- Oxide and fractionally distilled. B.P. 340 743.0 mm. All the liquids were shaken in a flask under reduced pressure before using in order to remove any absorbed air. Silica Gel Product - Silica Gel Corporation, Battemore. This gel was hand picked to remove the obvious blanks, crushed and screened through a 3 mm. sieve. ll EXperimental Evacuation: The tubes in groups of three as shown under description of apparatus were filled with silica gel, sealed on to the apparatus, and evacuated for a period of six hours at a temperature of 250°C, then sealed Off under vacuum. All tubes were sealed at a pressure from 10'4 mm. to 10"5 mm. as ShDWD by the McLeod gage. Weighings: After the sealed tube had cooled to room temperature it was scratched with a file at the points (a) and (b), then its weight in air (W1) and water (W2) deter- mined. The end of the side arm was then immersed in the liq- uid under investigation and the tip broken Off with forceps at the file scratch (b), thus filling the evacuated system with liquid. The top of the tube was broken Off at the file mark (a), the tube placed in a thermostat regulated to 25° 1 .0100 and the meniscus adjusted to the etched mark on the stem. The tube adjusted to volume was stOppered and weighed (W5). In most cases this adjustment was made two or more times and the mean weight used. The tube was emptied and filled with the liquid, meniscus adjusted to the mark and weighed as be- ffre (W6). The liquid was emptied out Of the tube and the dry weights of the tap and tip (W4) and tube (W3) determined. 12 Formulae & Computation: From the above weights the apparent density of the silica gel was calculated with the following formulae: Wt-g + W1 + (W1 - W3) Da - W1 1 Da Dw Db W1 - Weight Of evacuated tube gel system in air We - Weight of evacuated tube gel system in water Da - density of air Db - density Of brass D a density of water at temperature of weighings w Wt—g a corrected weight of tube and gel Wt = corrected weight Of tube, tip and top Wt8(W3+W4)+(W3+W4) D8. (l'i) Db W3 . weight of dry tube W4 2 weight of t0p and tip DP . density of pyrex glass we a corrected weight of gel ”8 '3 Wt-g ‘ Wt Wdl= Corrected weight of displaced liquid Well-W6 " (W5 “W8) 4‘ (W5 -W6) Dag; W5 = Weight Of tube liquid gel stOpper W6 a Weight of tube liquid stOpper Dgel a apparent density of gel D1 = density of liquid used 13 l4 Precision of Measurements The least accurate measurements are the weight of the bulb liquid gel and the weight of the bulb liquid. Their accuracy is determined by the ability to reproduce exact adjustments Of the meniscus. The following series Of weights were made on a tube plus water to determine with what accuracy the weights could be duplicated: Trial NO. Weight of tube d.m. 1 41.5461 + .0001 2 41.5459 - .0001 3 41.5461 + .0001 4 41.5459 - .0001 5 41.5463 + .0003 6 41.5456 -_ .0004 Av a d .0002 A.D. 0002 3—W— = 1 .00008 This degree of accuracy is of the same order as the accuracy Of the analytical balances used, thus the determinate errors are all of the same magnitude. ...... 15 Example of Calculation: Run #9 Ethyl Alcohol Bar 734.3 mm. 21°C Tube NO. 4 Evacuated 6 hrs to 10"5 mm. Temperature of thermostat 25°C Wt-g = W1 + (W1 - W2) Da - Wl-i Da DW wl . 51.9884 ow at 734.3 mm. 2100 = 0.99602 W2 . 8.9000 Da at 734.3 mm. 21°C - 0.001161 Wl-lg 43.0884 .1 a 0.1184 Db Wt-g 3 51.9884 + 43.0884 X .001161 - 51.9884 X .1184 X .001161 .99602 8 51.9884 + .0501 - .0071 wt"8 . 52.0314 DP DE W3 = 28.6295 ,; - 1 - 0.4444 DP '2725‘ W4 I 10.5050 1 I 1 I 0.1184 ‘53” '8.85 Dp Db wt 8 (28.6295 + 10.3060) + (28.6295 + 10.3060) X .3260 X .001161 I 38.2209 + 38.2209 X .3260 X .001161 I 38.2209 + .0144 I 38.2353 16 We ‘ "t-g ' "t . 52.0314 - 38.2353 - 13.7981 Wdl 3 W6 - (W5 - W8) + (W5 I W6) Da 1 W5 - 54.0150 Wdl = 44.8937-(54.0150-13.7961)+(54.0150-44.8937) X .1184 X .001161 I 44.8937 - 40.2189 + 9.1213 X .1184 X .00161 I 44.8937 - 40.2189 + .0013 . 4.6716 I)gel " W8 X D1 ? d1 Dgel - 13.7981 x 0.7851 3 2.9503 X 0.7851 D A T A Substance Run NO. Tube No. WS/Wdl Mercury 21 7 0.09494 " 8 0.09480 " 10 0.09490 Total 0.28464 Av 0.09488 Deviation of Mean Carbon disulphide 19 III 1.7200 " 7 1.7147 " 8 1.7270 Total 5.1617 Av 1.7206 Dgel 1.2849 1.2830 1.2844 3.8523 1.2841 2.1665 2.1598 2.1753 6.5016 2.1672 Deviation of Mean Benzene 4 2.5000 2.5009 2.5079 2.5041 01 k4 to F' to h‘ 10 2.5071 Tbtal 12.5020 AV 2.5004 Deviation of Meai 2.1848 2.1848 2.1854 2.1851 2.1854 10.9255 2.1851 Deviati on + |+ 1+ d+ .0008 .0011 .0003 .0022 .0007 I .0004 .0008 .0074 .0082 0.0164 .0054 .0031 .0003 .0003 .0003 .0003 .0012 .00024 .0001 Substance Carbontetra- chloride Nitrobenzene Run NO. 6 6 7 7 12 18 18 18 Iso propyl alcohol 17 Chloroform 17 16 16 16 Tube NO. wg/wdl D 1 2 1 3 4 Total AV 1.3538 1.3470 1.3493 1.3535 1.3451 6.7487 1.3497 gel 2.1543 2.1435 2.1471 2.1538 2.1405 10.7392 2.1478 Deviation Of Mean III 7 8 Total Av 1.8251 1.8322 1.8315 5.4888 1.8296 2.1870 2.1955 2.1947 6.5772 2.1924 Deviation Of‘Mean 10 X Total 2.8297 2.8168 5.6465 2.8232 2.2100 2.1999 4.4099 2.2049 Leviation of Mean III 7 8 1.4938 1.4932 1.4913 4.4783 1.4928 2.2108 2.2099 2.2071 6.6278 2.2093 Deviation of Mean Deviation + |+ F.- '+ |+ 4. '4' l4- |+ I+ .0065 .0043 .0007 .0060 .0073 .0248 .0050 .0020 .0054 .0031 .0023 .00108 .0036 .0021 .0051 .0051 .0102 .0051 .0036 .0015 .0016 .0022 .0044 .0015 .0009 D -.. Substance Petroleum. 15 ether 15 Water 2 2 4 5 6 10 8 Pentane 13 13 Run NO. Tube No. 0 3 Total AV Via/War 3.5320 3.5322 7.0624 3.5312 Dgel 2.2216 2.2228 4.4444 2.2222 Deviation Of‘Mean GUMGN III 3 Total AV 2.2358 2.2309 2.2365 2.2271 2.2275 2.2328 2.2332 15.6238 2.2320 2.2293 2.2244 2.2300 2.2206 2.2210 2.2263 2.2267 15.5783 2.2255 Deviation of Mean II X Total AV 3.6190 3.6173 7.2363 3.6181 2.2507 2.2496 4.5003 2.2502 Deviation Of Mean Deviation 1+ I-l- I+ .0006 .0006 .0012 1.0006 .0004 .0083 .0011 .0045 .0049 .0044 .0008 .0012 .0207 .0029 .0011 .0005 .0005 .0010 .0005 .0003 19 Substance Run NO. Tube NO. Wg/Wdl Dgel Deviation Ethyl alcohol 8 1 2.9159 2.2893 - $0115 8 2 2.9517 2.3174 + .0188 9 4 2.9503 2.3163 + .0155 9 5 2.9385 2.3054 + .0048 11 7 2.9213 2.2935 - .0073 11 8 2.9080 2.2831 - .0177 Total 17.5837 13.8050 .0783 Av 2.9308 2.3008 3 .0122 Deviation Of Mean : .0050 11 9 2.9788 2.3371 43 days Acetone 10 2.9589 2.3210 - .0021 10 2.9643 2.3252 + .0021 Total 5.9232 4.6462 .0042 Av 2.9818 2.3231 2 .0021 Deviation of Mean 1 .0015 Ether 14 0 3.3531 2.3730 + .0029 14 3 3.3812 2.3787 - .0029 Total 6.7143 4.7517 .0058 Av 3.3571 2.3759 1 .0029 Deviation Of'Mean '4- .0014 Summary of Data Substance Wg/Wdl Dgel Devia ti“ on of Mean Mercury 0.09448 1.2841 : .0004 1.277+ Carbontetrachloride 1.3497 2.1478 1 .0020 Carbondisulphide 1.7208 2.1872 : .0031 Benzene 2.5004 2.1851 3 .0001 Helium 2.188st Nitrobenzene 1.8298 2.1924 : .0021 IsoprOpylalcohol 2.8232 2.2049 : .0038 Chloroform 1.4928 2.2093 1 .0009 Petroleum ether 3.5312 2.2222 1 .0004 Water 2.2320 2.2255 1 .0011 2.228‘ Pentane 3.8181 2.2502 3 .0003 Ethyl alcohol 2.9308 2.3008 1 .0005 Acetone 2.9616 2.3231 : .0015 Ether 3.3571 2.3759 1 .0028 +Values by J. A. Ikerman 22 Table l and Table l-a are a comparison of the apparent densities of silica gel with thee determin- ed by Harkins and Ewingl for gas mask charcoal,and thqr are arranged in order of increasing apparent densities. This tabha also contains the calculated pore volume, per cent compressibility at 12,000 atmOSpheres, surface tension Y‘, viscosity 7") in absolute units, the ratio 2L and tie value of b for Vander Waal's equation. The pore volumes in these tables are calculated not on a basis of compressibility of the liquids, but on a change in density of the silica gel and charcoal as calculated by Harkins. This is not a true assumption, but was used as a basis of calculation due to the uncertainty Of the true block density of carbon. The pore volume is given.by the following equation: 1 - d in mercury d in liquld The density determined with mercury being the wetght of 1 cc. of charcoal in vacuumqfor the mercury does not wet the sur- face Or enter the pores of the charcoal. On this basis any increase in density is due to the weight of liquid altering the charcoal system. This same reasoning applys to a silica gel system. There appears to be no correlation between the two sets of data which is not at all unexpected. on 34 mm mm 3H me em em 30H N mmab omab omama 00mm comb 000$ omeoa Game omww a (\p em00.0 0H.8a 0000.0 00.nm «HH0.0 mm.am em00.0 ma pdopd HOH0.0 0.ms nmm0.0 ma.sm wom0.0 m.Hm e.ne 3000.0 00.00 e000.0 mn.an 0000.0 ma.0m 0.50 V .x mess: .80 non modem opsanmnd dofimsoe spnmooan> oooeasm o 0 message he mosam> 0.0m 0.5m nonpo seep whoa Hm.om mb.mm hoarse -mospo ooo.ma enamoseEOo R e HMO <0HHHm .00 a osdHo> H oapoe 0004.0 mb¢¢.0 0H¢¢.o nmmw.o mmma.o Hmma.o mmaa.o osaa.o naaa.o nma¢.o 0500.0 Hm0¢.o chow m maoaoap aaa oHnom ++ monosnoas.<.8 + ++00momm.m 00am.m nonpm damn.m qupmod moon.m Honooaa Heaps momm.m snowmom +©mm.m mmmmom Hops; nonom mmmm.m .EScHonuem nmom.m Enouonoano Honooad m¢0m.m Ahmonm OmH «mma.m ceremonompflz .70me . m 85......” em HmmH.m meannem m80H.m oefimasmfie noopwo m>ea.m weapoanownpee nopneo +§§N.H meN.H hndohmz hpamnom pnenomme eHSdHA m a 24 00 00 00 00 H0 #0 00 0b 0H 40H x 0000 0NHO omab 0000 0000 0H0¢ 000$ NO0H 00mm 0. 8 0 0000.0 ¢m00.0 0000.0 0000.0 0000.0 0000.0 0000.0 0mm0.0 HOH0.0 Na mpfinb 33888. 5:8an 0 A<00m onom 0 mNH.m 0mH.m NHH.N 000.N m¢0.N 0H0.N 000.N N00.H 000.H 000.H 000.0 hpamnmm anemones N 0000200 nonpm 0200004 oGHQHSm nae nopneo Hmnpm .Edoaospom onoahmnm onmunmm EHOHOHOHQQ son -ooH< demon» H099...» hunchez 003024 a 25 Table 2 and 2-a shows the pore volumes for carbon and silica gel recalculated on a basis of density change. Using a density of 2.26 for the true density Of the charcoal for this was the value found by howard and Halett3 using helium as a non-polar indifferent medium and checks very closely with their value determined for graphite. This density is also verified by the fact that the xray analysis made by Debye and Scherreré shows no differelce between graphite and charcoal. In recalculating it should be pointed out that the pore volume Of silica gel, a density of 2.651(7),has been used as the true density for the gel. 2.651 is ths density of quartz and is based on the work Of Berle and Urban4 using ether as a liquid. They obtained a value of 2.625 for a gel that had been dehydrated with hydrochloric acid and a wine of 2.685 for quartz. This same gel when activated at 3000 gave an apparent density with ether of 2.390 at 200. This is in agreement with our value determined with ether. The value 2.651 may be too high, but in calculat- ing the degree to which the various liquids must be compressed to give the apparent density measured, we are using the limiting value,for 2.651 is the maximum density of quartz and will give the maximum.pore value for 1 cc. of gel. Thus in calculating the volume change in the various liquids, we are determining the minimum possible. The following values are also tabulated in tables 2 and 2-a: Normal density of liquid at 25c, grams of 26 liquid adsorbed per cc. of system, grams liquid adsorbed per gram gel or carbon, density Of adsorbed liquid, com- pression of 1 cc. of liquid, volume of liquid adsorbed per cc. Of system, available data per cent compressibility of liquids at 8000 atmospheres, and pressure necessary to cause compression. The pressure calculiions are only approximations,as no exact data exists for the higher press- ures. 27 000080 Hoospfino Haoofiaoenopna H wnfippdz + sm>am.0809 oz «000. +nopos 000.0H 00.00 0040.0 0400.0 0000.0 0000.0 0000.0 ss0s.0 nonom 000.00 s0.0m 4800.0 0000.0 2000.0 0000.0 0000.H 440s.0 ooopooe Honooaa 0so.0m 00.00 H000.H 0000.0 ossa.a 000s.0 s0a0.H 0000.0 -Hsnsm 8000.0 0000.0 s0sm.a 4000.0 0000.0 0200.0 onopoom 000.00 .ao.ss 0430.0 0040.0 0000.0 0000.0 «030.0 0000.0 names Hm 9.0 0004.0 0040.0 4000.0 0000.0 0000.0 0000.0 asoaoaom 0000.0 0400.0 440s.a 0000.0 0000.0 0004.0 anoeonoano Honooaa 00sH.H 0003.0 000s.a Haas.0 0000.0 000s.0 -asaonaoaH OdmNdmn 0000.0 0000.0 0000.0 0008.0 0000.0 0000.0 -onpna 0000.0 0000.0 seas.a saos.0 0000.0 00s0.0 oooaoom ooneaoafio 003.00 00.00 0004.0 a00s.0 snas.s 0000.0 0000.0 0000.0 -aoonoo oos uncanosnpop sm¢0.0 0000.0 H0s0.H 0040.0 s000.0 0000.0 -oooaoo 0400.0H hunches .p< 500000 .04 0000 an aspen 0o .oo on assess o00.0 .oo non o00 005004 when commmne nmm coexdmoe commonweOo deepened sanw Hoe connomec Ho 009m Awfioo R .dHA Ho .Ho> .004 .oo H no 0000200 .000 mango .daq manna hpfinnem ufisdfiq 00 00H0. EHBmWM 00 H MEDAO> mmom 00 000$. Ememwm 00 H AMO Ho> HMU 40HHHO N oases 28 000.00 00.00 000.00 00.00 000.00 00.00 000.00 00.00 000.00 40.00 .00800 00000 0000 00 1&00800 0000000 onsmmmnm {800 0 so 0000. Hnoom Ham.H 00>.H 000.0 nmm.H H¢n.H mom.a H00.o mon.H Hmm.o 000000 .00 00m 00900000 .000 00 0o0 flmemwm 00 H MEDAOP mmom oo bmmn. dim oHan mmanma 000.0 @00.0 000.0 000.0 mmm.o 000.0 040.0 000.0 m¢n.o 900.0 Hm0.d 000.0 mm0.o 000.0 000.0 N00.H 009.0 000.0 000.0 000.0 000.0 mom.0 nnm.H 000.0 000.0 000.0 000.0 000.0 000.0 mmm.0 nom.H 000.0 000.0 000.0 000.0 000.0 000.0 000.0 000.0 000.0 00 0000000 000000 00000000 caoo.000 00n00000 Mo 8000 00m connomww .00 H 0000009 .000 madno .000 @8006 00000000 0000000000000 0 0000.0 0000000 4400.0 0000000 0000.0 Amapm 000000000 0000.0 -000000 00000 0000.0 200000000 0000.0 000000-0 0050.0 mdmNflmm 0004.0 0000000000 0000000 0000.0 -000000 0000.0 00000 0400.00 0000002 .oo 00% com .000 Mo 0000000 000000 Ememwm 00 H HOP H¢oom