REFRACTIVE INDEX IN BINARY AND TERNARY MIXTURES WITH DIETHYLENE GLYCOL, 1,4-DIOXANE AND WATER BETWEEN K

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1 U.P.B. Sc. Bull., Seres B, Vol. 7, Iss. 4, 00 ISSN REFRACTIVE INDEX IN BINARY AND TERNARY MIXTURES WITH DIETHYLENE GLYCOL,,4-DIOXANE AND WATER BETWEEN K Olga IULIAN, Amala ŞTEFANIU, Oaa CIOCIRLAN 3, Aca FEDELEŞ 4 S-au determat expermetal ş s-au corelat dc de refracţe petru amestecurle bare ş terare cu apă,,4-doxa ş detleglcol la 93.5 K, K ş 33.5 K pe îtreaga gamă de compozţ. Petru a calcula dc de refracţe s-au utlzat ecuaţle predctve Loretz Lorez, Weer, Heller, Gladstoe Dale, Arago Bot s Edwards; s-a aalzat acurateţea de calcul a acestora. Valorle măsurate expermetal pot f utlzate petru a obţe depedeţa propretate - compozţe petru amestecurle cu glcol studate.ecuaţa Loretz- Loretz, cu u suport teoretc avasat, poate f utlzată cu succes petru toate sstemele. Refractve dces for bary ad terary mxtures cotag water,,4- doxae ad dethylee glycol were expermetally measured ad correlated at 93.5 K, K ad 33.5 K over the etre rage of compostos. Loretz Lorez, Weer, Heller, Gladstoe Dale, Arago Bot ad Edwards predctve equatos were used to calculate the refractve dex; ther accuracy was aalyzed. The expermetal values ca be used to obta the property - composto depedeces for the studed mxtures wth glycols. The Loretz Lorez equato havg a advaced theoretcal support ca be used successfully for all systems. Keywords: refractve dex, predcto, dethylee glycol. Itroducto The kowledge of refractve dex of lqud mxtures at dfferet temperatures s a mportat step for ther structural characterzato. Alog wth other thermodyamc data, refractve dex values are also useful for practcal purposes egeerg calculatos. Refractve dex s useful to assess purty of substaces, to calculate the molecular electroc polarzablty [], to estmate the Prof., Dept. of Appled Physcal Chemstry ad Electrochemstry, Uversty POLITEHNICA of Bucharest, Romaa, e-mal: olgaula@yahoo.com PhD studet, Dept. of Appled Physcal Chemstry ad Electrochemstry, Uversty POLITEHNICA of Bucharest, Romaa, e-mal: astefau@gmal.com 3 Assstat, Dept. of Appled Physcal Chemstry ad Electrochemstry, Uversty POLITEHNICA of Bucharest, Romaa, e-mal: cocrla_o@yahoo.com 4 PhD studet, Dept. of Appled Physcal Chemstry ad Electrochemstry, Uversty POLITEHNICA of Bucharest, Romaa

2 38 Olga Iula, Amala Ştefau, Oaa Cocrla, Aca Fedeleş bolg pot wth Messer's [] method or to estmate propertes such as vscosty [3] ad other thermodyamc propertes. Ths work cotue our research o thermodyamc propertes of systems wth glycols [4,5] ad presets expermetal data cocerg refractve dces of the bary ad terary systems cotag water,,4-doxae ad dethylee glycol betwee 93.5 ad 33.5 K. The data for 98.5 K were preseted prevously [6]. The systems wth water ad compouds cotag hydroxyl groups, lke glycols havg both hydrophlc ad hydrophobc groups, are commoly used as chemcal ad bochemcal reacto meda. The most frequetly employed equatos to correlate the refractve dex for lqud mxtures wth specfed composto are those of Loretz-Lorez, Weer, Heller, Gladstoe-Dale, Arago-Bot ad Edwards [7]. Loretz-Lorez equato ca be appled for large composto domas, the others are recommeded for more dluted solutos. Weer ad Heller equatos are vald oly f the volumes are addtve. Arago-Bot equatos have the same advatages ad dsadvatages as Gladstoe-Dale equato: they gve the best results for systems wth ear-deal behavor. By our kowledge, the bary mxtures wth water ad glycols [8,9] are scarcely studed ad the bary ad terary systems wth,4 doxae ad dethylee glycol have ot bee yet studed.. Expermetal Chemcals. The aalytcal-reaget-grade,4-doxae from Merck was dstlled at K to collect the mddle fracto; the water was twce dstlled ad the dethylee glycol (DEG) from Merck was dstlled at K vacuum (aroud 3.87 kpa). The purty of the materals was checked by gas chromatographc aalyss (over 99.5 mass %). The comparso wth lterature of refractve dex values for pure compoets s preseted Table. Apparatus ad procedure. The mxtures wth desred composto were prepared volumetrcally. The accuracy of the mole fracto was estmated at ±0.00. All mxtures were completely mscble over the whole composto rage. Refractve dex of the mxtures at the sodum D-le was measured wth Abbe refractometer, thermostated wth ± 0.05 K accuracy. The precso of the measuremets was ± A average of trplcate measuremets was cosdered.

3 Refractve dex bary ad terary mxtures wth dethylee glycol,,4-doxae ad water 39 Table : Expermetal ad lterature values of refractve dex for pure compouds at 98.5 K Refractve Pure compoud dex, dethylee water,4-doxae D glycol Expermetal Lterature.334 [0].335 [].339 [].400[3].40 [4].440 [5] 3. Results ad dscussos The obtaed expermetal refractve dex values for the bary systems: water + dethylee glycol,,4-doxae + dethylee glycol ad for terary systems: water +,4-doxae +EG, water +,4-doxae + DEG at 93.5 K, K ad 33.5 are preseted K table. For 98.5 K, the varato of the refractve dex wth composto for water +,4-doxae dethylee glycol terary system s showed Fg.. The obtaed data were used to test the Loretz-Lorez, Weer, Heller, Gladstoe-Dale, Arago-Bot ad Edwards mxg rules (Eqs. -6, respectvely) order to predct the refractve dex of bary ad terary mxtures usg refractve dces of pure compoets [6]. = ϕ + ϕ () = ϕ + + () 3 = ϕ m m m = + ( ) + ϕ ( ) = ϕ / (4) = ϕ (5) + ϕ (3) = ϕ + ϕ (6)

4 40 Olga Iula, Amala Ştefau, Oaa Cocrla, Aca Fedeleş I ()-(6), represets the refractve dex of the mxture,, are the refractve dces of pure compoets, φ, φ are the volume fractos of compoets. I order to evaluate the method accuracy, the stadard devato (σ) ad the average percetage devato () were calculated as follows: σ = = ( exp calc ) 0.5 (7) 00 = = exp exp calc (8) where exp, calc are the expermetal ad calculated values ad are the umber of expermetal data. The results of the predctve calculato for the refractve dex, the stadard devato ad average percetage devato are preseted Table 3. For the bary systems the method proposed by Loretz-Lorez, havg a advaced theoretcal support based o the addtve property of the molar refractos of pure compoets, ca be used wth good results for all systems. Good results are obtaed wth Gladstoe Dale, Edwars, Heller ad Weer (very smlar wth Heller) models. Thus, the stadard devato rage betwee 0.04 ad 0., whle the average percetage devato, betwee 0.6 ad 0.8, whe usg Loretz-Lorez equato. For the terary systems the best results are obtaed, as the case of bary systems, wth Loretz-Lorez equato; approprate results are gve by Gladstoe Dale, Heller, Weer ad Edwards equatos, cted order of creasg error of calculato ( %). Geerally, the predcto for bary systems s better tha for the terary oes. From the Table 3 t ca be see that all cases the Loretz-Lorez mxg rule gave the best results. I all cases the Arago-Bot equato gave poor predcto for both bary ad terary systems.

5 Refractve dex bary ad terary mxtures wth dethylee glycol,,4-doxae ad water 4 water ()+ DEG () Refractve dex for bary ad terary mxtures at dfferet temperatures,4-doxae () + DEG () water()+,4-doxae()+deg(3) Table X X X X X X T = 93.5 K T = K

6 4 Olga Iula, Amala Ştefau, Oaa Cocrla, Aca Fedeleş T = 33.5 K DEG (3) water (),4-doxae Fg.. Refractve dex predcto versus composto for the terary system water()+,4- doxae()+deg(3) at 98.5K usg Gladstoe Dale model

7 Refractve dex bary ad terary mxtures wth dethylee glycol,,4-doxae ad water 43 Table 3 Stadard devatos (σ) ad average percetage devato () as results of predctve models at dfferet temperatures System T, K Loretz Lorez σ 0 σ 0 Weer Heller σ 0 Model Gladstoe Dale σ 0 Arago Bot σ 0 Edwards σ 0 water+ DEG,4- doxae+ DEG water+,4- doxae+ DEG Coclusos Two bary ad oe terary systems cotag dethylee glycol were studed order to obta the refractve dex data at dfferet temperatures (93.5 K, 303.5K ad 33.5K). The expermetal data were used to test the capablty predcto of Loretz-Lorez, Weer, Heller, Gladstoe-Dale, Arago- Bot ad Edwards models. All predcto methods represet geerally well the expermetal data. The best results were obtaed wth Loretz-Lorez equato. As expected, the calculated refractve dex wth Arago-Bot equato s usatsfactory. The obtaed data o refractve dex are useful determg the composto of bary ad terary mxtures wth dethylee glycol.

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