Internatinal Jurnal f Theretical & Applied Sciences 6(1): 43-49(2014) ISSN N. (Print): 0975-1718 ISSN N. (Online): 2249-3247 Effect f Temperature n the Micelle Frmatin f Aninic Surfactants in the Presence f Different Cncentratins f Urea Sandeep Kumar*, Punam Yadav*, Dinkar Malik* and Vijai Malik ** *Department f Chemistry, M.S. Cllege, Saharanpur, (UP) ** Department f Btany, M.S. Cllege, Saharanpur, (UP) (Crrespnding authr Sandeep Kumar) (Received 15 December 2013, Accepted 21 March, 2014) ABSTRACT: The micellar behaviur f aninic surfactants, ptassium ddecyl sulphate, sdium ddecyl sulphate, sdium ddecyl benzene sulphnate (KDS, NaDS and NaDBS) in presence f different cncentratin f urea (0.5-2.0 M) in 2.5% butanl-water systems at fixed temperature (35ºC) has been measured by cnductivity measurements. The CMC values f aninic surfactants increased with the additin f urea, butanl- water systems at fixed temperature (35ºC). Varius thermdynamic parameters have been reprted. Keywrds: Ptassium ddecyl sulphate (KDS); Sdium ddecyl benzene sulphnate (NaDBS); Sdium ddecyl sulphate (NaDS); Critical micelle cncentratin (CMC); Cnductivity (). I. INTRODUCTION The prperties f aqueus slutins f aliphatic mnhydric alchls are f interest in the field f surface chemistry; especially their effect n the slutins. One is that urea acts as a water structure breaker (indirect mechanism). The ther is that urea participates in the slvatin f hydrphbic chains in water by replacing sme water mlecules in the hydratin shell f the slute (direct-mechanism). phenmenn f micellizatin f surfactants. Kabir-ud-din et. al. (1996) reprted that critical Fendler et. al. (1975) studied that water-alchl surfactant systems are s frequently used as media in the studies f chemical equilibria and reactin rate, it is very essential t investigate the nature f the alkyl grups in the alchl n the CMC f surfactants. Several reviews exist n micellizatin f surfactants in aqueus media were studied by Linfied et. al. (1976). Bahadur et. al. (1982, 1983) studied that micelle frmatin in aqueus slutin is well knwn t be affected by a number f envirnmental factrs such as ph, inic strength, temperature and the presence f inrganic and rganic additives. The micelle frmatin in an aqueus slutin is knwn t be affected by inrganic additives and there have been many investigatins cncerning the effects f rganic additives n the CMC f aninic surfactants. Bahadur et. al. (1998) nticed the effect f rganic additives n the micellar behaviur f inic and nn-inic surfactants in water has been well studies micelle cncentratins (CMC) f inic and nninic surfactants significantly increase with the additin f urea in aqueus slutins. Asakawa et. al. (1995) studied the actin f urea in aqueus slutin shwed that urea had a negligible influence n the water structure. Bahadur et. al. (2003) bserved the effect f plymer as additives n sdium ddecyl sulphate. Abdul- Rahem et. al. (2009) nticed the physichemical prperties f hydrxyl mixed ether HMEn surfactants and their interactin with sdium ddecyl sulphate. Chen et. al. (2009) studied the effect f calcium ins cncentratin n the faming pwer f aninic surfactants. Parekh et. al. (2011) studied that aninic-catinic surfactants systems f sdium ddecyl trixyethylene sulfate with catinic Gemini surfactants. Patel et. al. (2009) bserved that micellizatin f sdium ddecyl sulfate and plyxyethylene ddecyl ether in slutin. Varade et. al (2005) nticed that miceller behaviur f by sme authrs with the utcme that aliphatic mixture f sdium ddecyl sulfate and alchls have been f particular interest. Enea et. al. (1982) studied the use f urea as a denaturant f prteins is well knwn. Khuarski et. al. (1984) bserved that the presence f urea and its derivatives mdifies the prperties f aqueus slutins. Tw different mechanisms have been ddecyldimethylamine xide in aquus slutin. Bharatiya et. al (2009) bserved that urea induced demicellazitin f plurnic L-64 in water. Kumar et. al. (2014) studied the effect f urea and butanl n the micelle frmatin f aninic surfactants at different temperature. prpsed t explain actin f urea n aqueus
II. EXPERIMENTAL PROCEDURE A. Materials Extra pure sdium ddecyl sulphate (B.D.H.) after recrystallizatin was used fr the preparatin f ptassium ddecyl sulphate (KDS). Ptassium ddecyl sulphate was prepared by direct metathesis. After recrystallizatin, it was used fr physical prperties. Sdium ddecyl benzene sulphnate was purchased frm Lba Chemie Pvt. Limited, Mumbai, India. Methanl, prpanl and butanl were all B.D.H. Labratry reagent while urea was purchased frm Merck (Merck Schuchardt OHG, Germany). Triple distill water btained frm all pyrex glass assembly was used thrughut studies. B. Measurement Butanl-water mixtures (2.5%) f several cmpsitin f urea (0.5-2.0 M) were prepared by mixing requisite quantity f alchl in water. Stck slutin f surfactants was prepared by weighing. The cnductance measurements f surfactant slutins were made by Elic cnductivity meter (Mdel CM-180) at a frequency f 1000 Hz using platinized electrde f knwn cell cnstant. After measuring the cnductivity f slvent, small vlume f the stck slutin fr dilutin was added and the cnductivity nted after each additin and thrugh mixing t a cnstant reading. The cnductivity (κ ) was calculated after applying the slvent crrectin. The CMC values were determined at the breakpint f nearly tw straight line prtin in the Kumar, Yadav, Malik and Malik 44 cnductivity versus cncentratin plts. The CMC f the surfactants in the presence f urea, butanl in water at fixed temperature (35ºC). III. RESULTS The κ values f KDS in pure water at different temperatures (30-45 C) are reprted in Table 1. These values were fund in clse agreement t thse reprted previusly. Als the CMC values btained frm κ vs. C plts in pure water were the same (Table 2) as reprted earlier. The κ values f, NaDS using different cncentratin f urea (0.5- ) in 2.5% butanl-water system at 35 C are reprted in Table 3 respectively. The increase in κ values in presence f urea at fixed temperatures (35ºC) and in butanl-water systems studied may be explained as: 1. Effect f temperature: Increasing inic mbility with increase in temperature. 2. Effect f alkanls: (a) Change in the nature f the slvent. (b) Partitining f alchl between water and micellar phase, the alchl frm mixed micelles with the surfactant by the incrpratin f the hydrcarbn part f the alchl in micelles. (c) Increase in the number f the free cunter ins frm the duble layer. (d) The liberatin f surfactant in frm the micelle. Table 1: Cnductivity κ fr KDS in pure water at different temperatures (30-45 C). Pure water Cncentratin f KDS in Mle litre - 1 0.002 0.004 0.006 0.008 0.010 0.012 0.014 κ x 10 6 (Ohm -1 cm -1 ) Temperature C 30 C 35 C 40 C 45 C 70 110 165 210 230 270 295 100 160 220 270 320 360 395 140 200 265 325 375 430 480 170 240 310 385 445 490 535 Table 2: CMC values fr KDS, NaDS and NaDBS in pure water at different temperatures (30-45ºC). Temperature 30ºC 35ºC 40ºC 45ºC CMC x 10 3 CMC x 10 4 KDS NaDS NaDBS 8.53 8.35 10.0 9.00 8.50 12.5 9.25 8.65 13.8 9.50 8.80 15.0
3. Effect f urea: The presence f urea and its derivatives mdifies the prperties f alkanl-water systems. Urea is suppsed t act as water structure breaker and its derivatives participate in slvatin f hydrphbic chains in water by replacing sme water mlecules in the hydratin shell f the slute. Kumar, Yadav, Malik and Malik 45 The CMC values fr each system were btained by κ vs. C plts (sme representative set f figures are reprted in Fig. 1) and all the values s btained are reprted in Table 4. Table 3: Cnductivity κ fr NaDS in the presence f different cncentratin f urea (0.5-) and 2.5% butanl-water system at 35 C. 2.5% butanl-water system Cncentratin f NaDS in Mle litre - 1 0.002 0.004 0.006 0.008 0.010 0.012 K x 10 6 (Ohm -1 cm -1 ) Cncentratin f urea 490 660 830 960 1100 1240 610 790 690 1100 1230 1370 700 900 1100 1240 1300 1495 800 1000 1125 1260 1395 1505 Fig. 1. Plts f Cnductivity Λ Μ Vs Cncentratin f KDS in Presence f Different Cncentratin f Urea and 2.5% Butanl-Water System At 35 ºC. The mlar cnductance ( Λ M ) calculated frm the cnductivity data f the surfactant slutin, decreases with increasing cncentratin f surfactants (KDS, NaDS and NaDBS). A steep decrease in Λ M values upt 0.0025 M surfactants cncentratin (KDS, NaDS) which afterwards decrease slwly with increasing cncentratin f surfactants. The similar trends were bserved in all the systems. Hwever in NaDBS the steep decrease in Λ M values were nticed at the cncentratin f 0.00025 M. This may be due t the tendency f the surfactants t frm aggregates at higher cncentratins. Hwever, the CMC values culd nt be determined frm the plt f Λ M vs. C (Fig. 2), which are cncave upwards with increasing slpes. The general equatin (1) was used t determine the behaviur f surfactant slutins which hlds gd fr all the system as well as at different temperatures. Lg Λ M = A+ B lgc.(1)
Kumar, Yadav, Malik and Malik 46 Fig. 2.Plts f Mlar Cnductance Λ Μ vs Square Rt f Cncentratin f KDS in Presence f 0.5 M Urea in 2.5% Butanl-Water System at Different Temperatures. Table 4: CMC values fr KDS, NaDS and NaDBS in presence f different cncentratin f urea (0.5- ) and 2.5% butanl-water system at 35ºC. Urea cncentratin CMC x 10 3 CMC x 10 4 KDS NaDS NaDBS 4.10 5.05 7.05 4.25 5.32 7.52 4.75 5.58 8.00 4.95 6.00 8.39 Table 5: Values fr cnstant A (lg Λ C = 1 ) fr KDS, NaDS and NaDBS in the presence f different cncentratin f urea (0.5-) and 2.5% butanl -water system at 35ºC. Cncentratin f urea The values f A fr all the surfactant in different urea-butanl-water systems (Table 5) lg Λ M fr zer values f lg C (i.e., C = 1) and B (Table 6) were determined by extraplatin f the linear plts f lg Λ Μ vs. lg C. These extraplated values f a cnstant A (i.e., lg Λ C = 1 ) signify the limiting mlar cnductance and are nly f theretical imprtance, since it was impssible t Surfactants NaDBS NaDS KDS 47.31 8.91 7.49 56.23 10.0 8.41 63.09 10.59 8.91 79.43 11.88 10.00 prepare such cncentrated slutins f surfactants due t their lw slubility. The standard Gibbs energies f micellizatin ( G ), in presence f urea (0.5-2.0 M) and 2.5% butanl-water system at 35ºC were calculated frm equatin (2) fr KDS, NaDS and NaDBS and are given in Table 7. G 0 = 2RT ln CMC x...(2)
Kumar, Yadav, Malik and Malik 47 Table 6: Values fr cnstant B fr KDS, NaDS and NaDBS in the presence f different cncentratin f urea (0.5-) and 2.5% butanl-water system at 35ºC. Cncentratin f urea Surfactants KDS NaDS NaDBS Table 7: Thermdynamic parameters fr KDS, NaDS and NaDBS in the presence f different cncentratin f urea (0.5-2.0 M) and 2.5% butanl-water system at 35ºC. (a) Thermdynamic parameter fr KDS. Cncentratin f urea - G (kj/mle) 29.47 28.53 27.94 27.63 KDS S (kj/mle) 0.257 0.139 0.136 0.134 H (kj/mle) 14.11 (b) Thermdynamic parameter fr NaDS. Cncentratin f urea 1.0 M - G (kj/mle) 26.99 26.76 26.52 26.05 (c) Thermdynamic parameter fr NaDBS. Cncentratin f urea - G (kj/mle) 37.12 36.78 36.43 36.19 The standard enthalpy change f micellizatin ( H ) per mle f mnmer f KDS, NaDS and NaDBS were calculated frm linear plts f lg CMC x vs. 1/T (Fig. 3) using equatin (3) and are 14.11, 16.23, 16.39 kj/mle respectively. lg CMC x H = + C.(3) 2.303 RT NaDS S (kj/mle) 0.140 0.130 0.129 0.126 NaDBS S (kj/mle) 0.171 0.179 0.177 0.176 H (kj/mle) 16.23 H (kj/mle) 16.39 The standard entrpies f micellizatin ( S ), in presence f urea (0.5-2.0 M) and 2.5% butanlwater system at 35ºC fr KDS, NaDS and NaDBS were calculated frm equatin (4) and are given in Table 7 H G S =.(4) T
Kumar, Yadav, Malik and Malik 48 Fig. 3. Plts f Lg CMC x Vs IV. DISCUSSION 1 10 4 T Micelle frmatin is assumed t ccur when the energy released as a result f aggregatin f hydrcarbn chain f the mnmers is sufficient t vercme the electric repulsins between inic head grups and t balance the decrease in entrpy accmpanying aggregatin. It has als been nticed (Table 4) that CMC values f KDS, NaDS and NaDBS in the presence f 0.5- urea in 2.5% butanl-water system at 35 C shws a cntinuus increase with increase in cncentratin f urea. The additin f urea t the micellar slutin is well knwn t increase the CMC and is related t the free energy f transfer f an alchl mlecule frm the water t micellar phase. It may be suggested that in the presence f these butanl, the plar grups at the micelles surface wuld lead t reductin f the effect due t repulsin f the charged plar head grups and hence the CMC decreases. The hydrphbic effect assciated with the hydrphbic miety f the alkanl mlecules als favurs micellizatin and will increase as the length f hydrcarbn chain f the alkanl increases. This explains the decreased lwering f the CMC as the number f methylene grup increases in alkanl series. Table 5 reveals that the values f A increase with increasing the f Surfactants in Presence f 0.5 M Urea in 2.5% Butanl- Water System at Different Temperatures. cncentratin f urea (0.5-) in 2.5% butanlwater system. The values f cnstant B were btained frm the slpes f plts f lg Λ Μ vs. lgc fr KDS, NaDS and NaDBS in all the systems, and are reprted in Table 6. The values f B were als fund independent f cncentratin f urea (Table 6) in 2.5% butanl-water system at 35 C fr all the surfactants. V. CONCLUSION In fact the CMC lwering f surfactants by the small additin f alchls may be due t their direct actin n water structure and the subsequent additin may cause secndary effects such as their slubilizatin in micelle and decrease f hydrphbic effect. This further supprts the view that the frmatin f the cavity f mre rdered water mlecules is favred by the lng hydrcarbn chain f the alchls. In the presence f such a cavity, a decrease in CMC is nt unexpected. The rle f water cavity in the micelles frmatin has been further verified by studying the effect f urea n CMC. Urea is a strng water structure breaker in presence f alchls it may destry the cavity f rdered water structure. It is, therefre, expected that the CMC shuld increase with the increase in the cncentratin f urea.
These results indicate that the additin f urea results in the breaking f water structure even at the cncentratin f alchls where it is expected t be mre rdered. This partitin f additive between the slutin and the micelles may be sensitive t the structure f the plar third cmpnent and the temperature. REFERENCES [1]. Fendler JH, Fendler EJ. Catalysis in micellar and macrmlecular system, Academic Press, New Yrk 1975. [2]. Linfied WM. Aninic surfactants, Vl. 1, Marcel Dekker, N. Y. 1976. [3]. Bahadur P, Gupta A, Gswami AK. Studies n the cnductance behaviur f aninic surfactants in plar slvents. Tenside Surf. Deterg, 1982, (19), 88-92. [4]. Bahadur P, Gupta A, Bahadur P. Studies n visccity behaviur f aninic surfactants in plar slvents. Tenside Surf. Deterg.1983, (20), 142-144. [5]. Enea O, Jliceur J. Heat capacities and vlume f several ligpeptides in Urea-water mixtures at 25ºC. Sme implicatins fr prtein unflding, J. Phys. Chem; 1982, (86), 3870. [6]. Khuarski RA, Rssky PJ. Mlecular dynamics study f slvatin in Urea-water slutin. J. Am. Chem. Sc; 1984, (106), 5786. [7]. Kabir-ud-Din, Kumar S, Aswal VK, Gyal PS. Effect f salt and rganic additives n micellar aggregatin f sdium ddecyl sulphate, J. Chem. Sc, Faraday Trans. 1996, (92), 2413. [8]. Asakawa T, Hashikawa M, Amda K, Miyagishi S. Effect f urea n micelle frmatin f Kumar, Yadav, Malik and Malik 49 flurcarbn surfactants, Langmuir. 1995, (11), 2376. [9]. Bahadur P, Chand M. Studies n plymer surfactant interactins and the effect f electrlyte and temperature. Tenside Surf. Det. 2003, (2), 105. [10]. Abdel-Rahem R, Ayesh AS. Physicchemical prperties f hydrxyl ether HMEn surfactants and their interactin with sdium ddecyl sulfate SDS. Tenside Surf. Det. 2009, (2), 105. [11]. Chen L, Sat F, Sanchez E. Effect f calcium ins cncentratin n the faming pwer f annic surfactants. Tenside Surf. Det. 2009, (6), 352. [12]. Parekh P, Varade D, Parikh J, Bahadur P. Aninic-catinic surfactants systems: miceller interactins f sdium ddecyl trixyethylene sulfate with catinic Gemini surfactants. Cllids surfaces A, 2011, (385), 111-120. [13]. Patel T, Gsh G, Aswal VK, Bahadur P. Micellizatin f sdium ddecyl sulfate and plyxyethylene ddecyl ether in slutin. Cllids. Plym. Sci. 2009, (287), 1175-1181. [14]. Varade D, Jshi T, Aswal VK, Gyal PS, Hassan PA, Bahadur P. Miceller behaviur f mixture f sdium ddecyl sulfate and ddecyldimethylamine xide in aquus slutin. Cllids. Surfaces A, 2005, (259), 103-109. [15]. Bharatiya B, Gu C, Ma JH, Kubta O, Nakashima K, Bahadur P. Urea induced demicellazitin f plurnic L-64 in water, Cllids Plymer Science, 2009, (287), 63-71. [16]. Kumar Sandeep, Yadav Punam, Malik Dinkar, Malik Vijai. Effect f urea and butanl n the micelle frmatin f aninic surfactants at different temperature, Ind. J. f Sci, 2014, (9), 8-14.