INDIAN J. CI-IEM., VOL. 20A, NOVEMBER 1981

TABLE1 - VOLUMEFRACTIqNS (q,A), DENSITIES(p), SOUNDVELOCITIES(U) AND ISENTROPICCOMPRESSIBIUnES(ks) OF BINARYMIXTURESOF CYCLOHEXYLAMINEWITH Il-ALKANES

q,A P u k. Ks q,A P u ks s,(g cm") (m sec") (T Pa-1) (g em:") (m sec") (T Pa-1)

CYCLOHEXYLAMINE+ll-HEXANE CYCLOHEXYLAMINE+ n-HEPTANE0 0.65065 1052 1389 0 0 0.67530 1112 1197 00.1358 0.67860 1096 1227 -56 0.1404 0.69999 1142 1095 -190.2022 0.69236 1116 1160 -77 0.2089 0.71219 1157 1049 -250.2535 0.70300 1136 1102 -88 0.3653 0.74042 115>7 <)42 -390.3714 0.72732 1172 1001 -97 0.4489 0.75568 1220 889 -430.4694- 0.74807 1204 922 -99 0.6054 0.78450 1264 798 -420.6154 0.77841 1252 819 -88 0.7564 0.81250 1311 717 -330.8167 0.82006 1320 700 -50 0.7004 0.80215 1291 748 -360.8871 0.83457 1343 664 -31 0.8572 0.83125 1340 670 -211 0.85782 1386 607 0 1 0.85782 1386 607 0

CYCLOHEXYLAMINE+ n-OCTANE CYCLOHEXYLAMINE+ n-NONANE0 0.69441 1148 1092 0 0 0.70<J98 1188 998 00.1047 0.71030 1170 1028 -13 0.0928 0.72229 l200 961 -10.2012 0.72630 1190 972 -19 0.1772 0.73400 1212 927 -20.3206 0.74443 1216 908 -28 0.2446 0.74349 1252 858 -80.4621 0.76739 1248 837 -31 0.4340 0.77113 1261 815 -130.5676 0.78478 1272 787 -29 0.5482 0.78821 1284 769 -140.6608 0.80024 12<)4 746 -25 0.6563 0.804·81 1307 721 -140.7742 0.81932 1321 698 -18 0.7825 0.82418 1335 681 -110.8896 0.83891 1353 651 -9 0.8802 0.83926 1351 647 -71 0.85182 1386 601 0 1 0.85182 1386 601 0

T (tera) = 10-12

TABLE 2 - VALUES OF PARAMETERSIN EQUAnON (3) ANDSTANDARDDEVIAnoNs a(Ks)

Binary mixture bo b1 b2of eyclohexylamine

withn-Hexanen-Heptanen-Oetanen-Nonane

-395.34 114.90 -12.45-162.05 - 15.34 -25.96-112.91 23.13 -13.72- 56.37 - 32.41 28.60

2221

T (tera) 10-12

tends to decrease the Kg value", Hence the negativeKs values for these mixtures may be due to inter-stitial accommodation of alkane, within the hydrogen-bonded structure. The increase in Ks values withincrease in chain length of n-alkane is qualitativelysimilar to that of excess volumes>. This suggeststhat the interstitial accommodation of alkanes be-comes hindered as the size of alkane molecule in-creases. The sign of excess volume VE and Ks are.not the same. Similar behaviour has been reportedby Kaulgud7, Kiyohara et at», Rao and Naidu9

and Subrahmanyam and Rajagopalw, Since thesign of excess volume and K; studied are not thesame, the nature of intermolecular interaction cannotbe predicted exactly but they give a qualitative ideaof the interactions present.

The authors (G. D. R. and G. N. S.) are gratefulto the CSIR, New Delhi, for the award of researchfellowships.

References1. DHARMARAJU,G., NARAYANASWAMY,G. & RAMAN,G. K.,

J. soln Chem., 10 (1981),79.2. RIDDICK, J. A. & BUNGER, W. B., Organic solvents 3rd

Ed. (Wiley Interseience, New York), 1970, pp. 595-601.3. TIMMERMANS,J., Physico-chemical constants of pure organic

compounds (Elsevier, New York), 1950,44, 63, 86, 98.

1110

4. NAIDU, P. R. & KRISHNAN,V. R., Trans. Faraday Soc.,61 (1965), 1341.

5. PANNETIER,G., KERN, M., ABELLO, L. & DJEGA-MARIA,DASSOU,G., C. R. Acad. Sci., Paris, Ser. C 264 (1961),1016.

6. KIYOHARA, O. & BENSON, G. c., J. chem. Thermody,11 (1979), 811. '

7. KAULGUD, M. V., Z. phys. Chem., 36 (1963), 365.8. KIYOHARA,0., GROUER, J. P. E. & BENSON,G. C., Can.

J. Chem., 52 (1974), 2287.9. RAO, M. V. P. & NAIDU, P. R., J. chem. Thermody., 8

(1976), 73.10. SUBRAHMANYAM,S. V. & RAJAGOPAL, E., Z. physik,

Chem., 85 (1913), 256.

Effect of Gamma Irradiation on Ion ExchangeCharacteristics of Titanium Vanadophosphate

NARENDRAJ. SINGH* & S. N. TANDONtDepartment of Earth Sciences, University of Roorkee,

Roorkee 247 672and

J. S. GILLDepartment of Chemistry, State University of New York at

Buffalo, New York 14214

Received 14 January 1981; revised 16 March 1981; accepted13 April 1981

The effect of gamma-irradiation (",10· rads from eo Cosource) on the exchange characteristics of titanium vanadophos-phate has been studied. The surface of the material is slightlyaffected on irradiation but the interior of the exchanger particlesremains intact.

THE eJ.ficacy ?f. titanium vanadophosphate\ anew morganic IOn exchanger, in the separation

tDepartment of Chemistry, University of Roorkee,Roorkee 247 672.

of a number of binary/ternary metal ions of analy-tical and radiochemical interest has been demons-trated earlier by Singh and Tandon-. The presentnote reports the effect of gamma rays (......,109 rads)from a 60COsource on physical appearance, exchangecapacity, Ks, values and chemical stability of titaniumvanadophosphate(TVP). Moreover, to have anidea of the nature of the damage imparted to thematerial upon irradiation, the rates of exchange ofRb+ /H+ system have been investigated.

All the chemicals used were of AR grade. Theradioisotopes 86Rb, 85+89Sr,l1omAg, I34CSand 160Tbwere obtained from Bhabha Atomic ResearchCentre, Bombay.

Titanium vanadophos phate alongwith Dowex 50resin was irradiated to a total gamma dose of 1X 109rads at a dose rate 6 X 106 rads hr ? from a 60COsource. The samples were water cooled at 10"Cso as to check deterioration if any due to high tem-perature.

As the rates of exchange were determined by thelimited bath technique, the equation developed byBoyd et a/. 2 and improved by Reichenberg" wasemployed. The instruments used and the procedureadopted were the same as reported earlier",

The physical appearance, exchange capacity, dis-tribution coefficient (Ka) values and chemical stabi-lity of irradiated and unirradiated samples of TVPare given in Table 1. For comparison the data onDowex 50 resin have also been included in Table 1.A perusal of the Table 1 indicates that the gammairradiation have a little effect on ion exchange charac-teristics of TVP. The capacity values and Ka valuesin general show a slight increase upon irradiation.The irradiated sample shows slightly increaseddissolution tendency in 5.0M HN03• These obser-vations indicate that some change, either super-ficial or in the core of the material, has occurredupon irradiation.

In the case of Dowex 50 resin it has been shown"that the resin loses about 15% of its initial exchangecapacity upon irradiation with gamma rays, whileirradiation in a nuclear pile fully decomposes theresin. The resin in the present investigation retainsonly-c- 50 % of its initial capacity and becomessticky, hence unsuitable for column operation onirradiation. Moreover, major part of the resin isfound in dark brown supernatant on keeping it in

NOTES

contact with 5.0M HN03• This is unlike the zirco-nium arsenophosphate ion exchanger which retainsits exchange characteristics even upon irradiationunder the similar conditions.

At low concentration (0.01 M) where the rate ofexchange is a composite of film and particle diffusionmechanism, the rate of Rb+ uptake is faster (Fig. 1)on irradiated sample than that on unirradiated one,probably because of some change in the surface uponirradiation. There may be an increase in the surfacearea due to superficial damage. This is supportedby the slight increase in the capacity value of theirradiated sample.

1.0,--------------_---.

0.9

;'

0.8~;'--

;' v

"if.--

0.1;::r/.

1.4'" /. //' /. /

/' /. ,!,6' -'" /0.6 / 1.2

/ //</ I

/F , I1.0o.s I. / /

/ /,I /,

0.4 / 0.8BtI /,

I /,0.3

/ /;; 0.6

/'10.40.2

0.1 0.2

Fig. 1 - Rates of Rb+/H+ exchange on irradiated (-) .andand unirradiated (- - -) samples of TVP at concentrationsO.OIM (0-0) and O.lM(e-e)[Particle size(r) =2.16 x IO-'cm]

TABLE 1 - PROPERTIES OF UNIRRADIATED AND IRRADIATED SAMPLES OF TITANUM VANADOPHOSPHATE ANDDowEX 50 RESIN

Ion Physical Ion exchange Kd (ml/g) from O.OIM HN03 Solubility in 5.0Mexchanger appearance capacity HN03 (gjlitre)

(rneq/g)Rb+ Cs+ Ag+ Sr2+ Tb3+ Ti V P

TVP (a) YeJlow granular 2.00 1515 4067 610.0 2.1 42.5 0.006 0.004 0.0::17(b) Greenish yellow

1573 4092 653.0 2.3 48.2 0.006 0.006 0.008granular 2.13

214.6 507.3 307.7 7326 ro- *Dowex 50 (a) Golden yellow 5.25(b) Dark brown 2.63 98.7 103.6 76.4 6326 7758 t

(a) Unirradiated sample; (b) irradiated sample*No effect; +Dark brown supernatant.

1111

INDIAN J. CHEM., VOL. 20A, NOVEMBER 1981

On the other hand, the plots of F and Bt againsttime (t) at a concentration 0.01 M for irradiated andunirradiated samples overlap, indicating similar ratesof exchange on the two samples. Moreover, the linearBt versus t plots at O.lOM concentration revealthat the rate of exchange is controlled by the particlediffusion mechanism and since it is associated withthe diffusion of ions inside the exchanger particlesit can be inferred that no damage is imparted to theinterior of the material.

Mr. Walter Becker, Brookhaven National Labo-ratory, New York, USA, is thanked for providingthe irradiation facilities. The financial supportfrom the UOC and CSIR, New Delhi, is gratefullyacknowledged.

References1. SINGH, N. J. & TANDON, S. N., Indian J. Chem., 19A

(1980), 502.2. BOYD, G. E., ADAMSON, A. W. & MYRES (Jr.), L. S., J.

chem. Soc., 69 (1947),2836.3. REICHENBERG, D., J. Arn. Chem. Soc., 75 (1953), 589.4. MATHEW, J., SINGH, N. J., GUPTA, C. B. & TANDON,

S. N., Indian J. Chem., 16A (1978), 524.5. ZSINKA, L., SZIRTES, L. & STENGER, V., Radiochem.

radioanal. Lett., 4 (1970),257.6. SINGH, N. J., GILL, J. S. & TANDON, S. N., Radiocliem,

radio anal. Lett., 41 (1979), 79.

Effect of Precipitation Conditions upon Physico-chemical Properties of Iron Oxide .Catalyst

G. SENGUPTA, N. K. MANDAL*, M. L. Ku DU & S. P. SEN

The Fertilizer (P & D) India Limited, Sindri

Received 23 June 1980; revised 13 April 1981; accepted6 May 1981

Physico-chemical properties of two hydrated iron oxide samplesobtained by precipitation (i) with ammonium hydroxide and(ii) with ammonium carbonate have been explained on the basisof acid-base and redox equilibria prevailing during precipita-tion from ferrous salt solution.

THE major component of the catalyst for watergas shift reaction is iron oxide which is pre-

pared by adding a base such as ammonium hydroxideor carbonate to a solution of iron salt. The com-position of the precipitate and hence its structureobviously depend upon the method of precipitation.This is reflected in the variation of properties suchas texture, catalytic activity, mechanical strength, etc.among catalysts manufactured by different processes.The present investigation deals with the physico-chemical studies using X-ray, TO, DTA and magneticmeasurement and the study of the acid-base andredox equilibria prevailing during precipitation oftwo iron oxide catalysts prepared by two differentprecipitation methods. It is felt that these data willbe very helpful in quality control during catalystproduction.

Ferrous sulphate, ammonia solution and ammo-nium carbonate used were all BDH (LR) gradechemicals. Nitrogen (Mjs Indian Oxygen Limited)

1112

was used as such. Ferrous sulphate solution wasprepared by dissolving the salt (50 g) in 1 % sul-phuric acid (500 mI). Ammonium carbonate and aconcentrated solution of ammonia (sp. gr. 0.91) wereused as precipitating reagents.

Precipitation titration was carried out in a beakercovered with a snugly fitting rubber stopper havingholes for introducing the glass electrode (for pHmeasurement) or platinum electrode and salt bridge(for emf measurement), burette tip and the gas inlettube. Nitrogen was bubbled through thes solutionvigorously to ensure good stirring. A ToshniwalpH-meter model CL-41 was used along with a Tosh-niwal calomel electrode and a Philips glass electrodetype GAT 130 for pH measurement. For emfmeasurement a Philips DC microvoltmeter GM 6020was used. X-ray photographs were taken with aGuinier camera using FeKoc radiation. TG andDT A measurements were done with a StantonTbermograv and a Gallenkamp DTA unitrespectively. A Gouy type magnetic balance wasused for magnetic measurements.

About 100 ml of the iron solution were used fortitration which was carried out at room temperaturein presence of nitrogen. After precipitation wascomplete, the precipitate was washed free from sul-phate and dried in air at 110°C. TO, DT A, X-rayand magnetic measurements were carried out withthe dried sample. The dried sample was finallycured in air at 500°C for 4 hr and characterized byX-ray and magnetic measurements.

It is seen that during precipitation both the pH andhalf-cell emf change very sharply. However, thenature of the change depends upon the precipitantused. In the presence of ammonium hydroxide thepH increases from < 1 to 10 whereas when ammo-nium carbonate is used the pH remains steady ,.....6.5even after complete precipitation. Similarly thehalf-cell potential changes from +0.56 to -0.64volts upon addition of excess ammonium hydroxidebut up to -0.13 volts if ammonium carbonate isused. Moreover after an equivalent amount of am-monium carbonate has been added, the half-cellpotential decreases sharply.

The above phenomenon can be discussed on thebasis of the E versus pH diagram (Fig. 1) from whicha probable composition of the precipitate can besuggested. In a solution of iron salt the followingequilibria can be considered along with their pub-lished E and K values'.

(a)(b)(c)

Fe2+ + 2e- ~Fe3+ + e- ~Fe(OH)z+e- ~

(e)

(f)

Fe" ; EO = -0.44 VFe2+; EO = 0.771 V

Fe" + 20H-; EO =-0.057 -0.059 pH

~ FeH + 20H-; KOso= [FeH)[OH-]= 10-15.1

Fe(OH)3 + e- ~ Fe(OH)2+0H-; E = 0.305-0.059 pH

Fe(OH)3 + e- ~ FeH + 30H- ; E = 1.20-0.059 (3) pH

~ Fe3+ + 30H-; KOso =[Fe3+][OH-P = 10-37

(d) Fe(OH)2

(g) Fe(OH)3