Volumetric properties of betaine hydrochloride drug in aqueous NaCl and KCl solutions at different...
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Volumetric properties of betaine hydrochloride drug in aqueous NaCl and KCl solutions at different temperatures Suresh Ryshetti a , Bharath Kumar Chennuri b , Raghuram Noothi a , Savitha Jyostna Tangeda a, **, Ramesh L. Gardas b, * a Department of Chemistry, Kakatiya University, Warangal 506009, India b Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India A R T I C L E I N F O Article history: Received 13 June 2014 Received in revised form 16 October 2014 Accepted 18 October 2014 Available online 23 October 2014 Keywords: Density Speed of sound Betaine hydrochloride drug Hepler’s constant Cosphere overlap model A B S T R A C T Densities (r) and speeds of sound (u) of betaine hydrochloride (B.HCl) drug (0.01–0.06) mol kg 1 in (0.10, 0.20 and 0.30) mol kg 1 aqueous NaCl and KCl solutions have been reported as a function of temperature at T = (293.15 –313.15) K and at atmospheric pressure. Using experimental data the apparent molar volume (V 2,f ), partial molar volume (V 2 1 ), transfer partial molar volume (D t V 2 1 ), apparent molar isentropic compressibility (K s,2,f ), partial molar isentropic compressibility (K s,2 1 ), transfer partial molar isentropic compressibility (D t K s,2 1 ), partial molar expansion (E 2 1 ) and Hepler’s constant (@ 2 V 2 1 /@T 2 ) P were calculated. Further, all these parameters are employed to understand the temperature and cosolute effects on B.HCl drug–solvent interactions. Cosphere overlap model is used to analyze the hydrophilic/ ionic-ionic interactions in (B.HCl drug + NaCl/KCl + H 2 O) ternary mixture. The sign of Hepler’s constant have been used to interpret the structure making or braking tendency of B.HCl drug in aqueous NaCl and KCl solutions at probed compositions and temperatures. ã 2014 Elsevier B.V. All rights reserved. 1. Introduction The solvation behavior of drug molecules in solutions has a significant role to understand the activity of drugs in biological system. It is difficult to understand these drug–solvent interactions directly in biological system, these interactions can be altered by the cosolutes such as salt, polymer, carbohydrate, osmolytes, surfactant, amino acid, protein, peptide, alcohol, etc., furthermore, drug–solvent interactions also vary with the temperature of the solutions [1–3]. However, it is possible for some extent to examine cosolute and temperatures effects on drug–solvent interactions through thermophysical properties at various temperatures and compositions [4–6]. Most of the biochemical processes occur in aqueous media, the drug–water molecular interactions and their temperature dependence play an important role in finding the drug action across the biological membrane [7]. We are engaged in systematic study of solvation behavior of B. HCl drug in various solvents [8] through thermophysical property measurements since volumetric and acoustic properties have been used as potential tools to understand and analyze the solvation behavior of solutes in aqueous and non-aqueous solutions [9–12]. In this work, we have studied the volumetric properties of B.HCl drug in aqueous NaCl and KCl solutions, to understand the molecular interactions at different temperatures and compositions of solute and cosolute. Densities (r) and speeds of sound (u) of (0.01–0.06) mol kg 1 B.HCl drug in (0.10, 0.20 and 0.30) mol kg 1 aqueous NaCl and KCl solutions have been measured as a function of temperature at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K and at atmospheric pressure. Results are interpreted in terms of ion–ion, hydrophilic-ionic, ion-hydrophobic, electrostatic interactions and structure making/breaking ability of B.HCl drug in aqueous NaCl and KCl solutions. To the best of our knowledge, densities and speeds of sound of B.HCl drug in aqueous NaCl and KCl solutions are not reported in the literature. 2. Experimental 2.1. Chemicals For the investigation of thermophysical properties of B.HCl drug in aqueous NaCl and KCl solutions, the following chemicals have been used; betaine hydrochloride were obtained from Sigma– Aldrich Co. and the structure of B.HCl drug shown in Scheme 1, sodium chloride supplied by Himedia Laboratory, potassium * Corresponding author. Tel.: +91 44 22574248; fax: +91 44 22574202. ** Corresponding author. Tel.: +91 99 08455351. E-mail addresses: [email protected] (S.J. Tangeda), [email protected] (R.L. Gardas). http://dx.doi.org/10.1016/j.tca.2014.10.019 0040-6031/ ã 2014 Elsevier B.V. All rights reserved. Thermochimica Acta 597 (2014) 71–77 Contents lists available at ScienceDirect Thermochimica Acta journa l home page : www.e lsevier.com/loca te/tca
Transcript of Volumetric properties of betaine hydrochloride drug in aqueous NaCl and KCl solutions at different...
Thermochimica Acta 597 (2014) 71–77
Volumetric properties of betaine hydrochloride drug in aqueous NaCland KCl solutions at different temperatures
Suresh Ryshetti a, Bharath Kumar Chennuri b, Raghuram Noothi a,Savitha Jyostna Tangeda a,**, Ramesh L. Gardas b,*aDepartment of Chemistry, Kakatiya University, Warangal 506009, IndiabDepartment of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
A R T I C L E I N F O
Article history:Received 13 June 2014Received in revised form 16 October 2014Accepted 18 October 2014Available online 23 October 2014
Keywords:DensitySpeed of soundBetaine hydrochloride drugHepler’s constantCosphere overlap model
A B S T R A C T
Densities (r) and speeds of sound (u) of betaine hydrochloride (B.HCl) drug (0.01–0.06) mol kg�1 in (0.10,0.20 and 0.30) mol kg�1aqueous NaCl and KCl solutions have been reported as a function of temperatureat T = (293.15 –313.15) K and at atmospheric pressure. Using experimental data the apparent molarvolume (V2,f), partial molar volume (V2
1), transfer partial molar volume (DtV21), apparent molar
isentropic compressibility (Ks,2,f), partial molar isentropic compressibility (Ks,21), transfer partial molar
isentropic compressibility (DtKs,21), partial molar expansion (E21) and Hepler’s constant (@2V2
1/@T2)Pwere calculated. Further, all these parameters are employed to understand the temperature and cosoluteeffects on B.HCl drug–solvent interactions. Cosphere overlap model is used to analyze the hydrophilic/ionic-ionic interactions in (B.HCl drug + NaCl/KCl + H2O) ternary mixture. The sign of Hepler’s constanthave been used to interpret the structure making or braking tendency of B.HCl drug in aqueous NaCl andKCl solutions at probed compositions and temperatures.
ã 2014 Elsevier B.V. All rights reserved.
Contents lists available at ScienceDirect
Thermochimica Acta
journa l home page : www.e l sev ier .com/ loca te / tca
1. Introduction
The solvation behavior of drug molecules in solutions has asignificant role to understand the activity of drugs in biologicalsystem. It is difficult to understand these drug–solvent interactionsdirectly in biological system, these interactions can be altered bythe cosolutes such as salt, polymer, carbohydrate, osmolytes,surfactant, amino acid, protein, peptide, alcohol, etc., furthermore,drug–solvent interactions also vary with the temperature of thesolutions [1–3]. However, it is possible for some extent to examinecosolute and temperatures effects on drug–solvent interactionsthrough thermophysical properties at various temperatures andcompositions [4–6]. Most of the biochemical processes occur inaqueous media, the drug–water molecular interactions and theirtemperature dependence play an important role in finding thedrug action across the biological membrane [7].
We are engaged in systematic study of solvation behavior of B.HCl drug in various solvents [8] through thermophysical propertymeasurements since volumetric and acoustic properties have been
* Corresponding author. Tel.: +91 44 22574248; fax: +91 44 22574202.** Corresponding author. Tel.: +91 99 08455351.
E-mail addresses: [email protected] (S.J. Tangeda), [email protected](R.L. Gardas).
http://dx.doi.org/10.1016/j.tca.2014.10.0190040-6031/ã 2014 Elsevier B.V. All rights reserved.
used as potential tools to understand and analyze the solvationbehavior of solutes in aqueous and non-aqueous solutions [9–12].In this work, we have studied the volumetric properties of B.HCldrug in aqueous NaCl and KCl solutions, to understand themolecular interactions at different temperatures and compositionsof solute and cosolute. Densities (r) and speeds of sound (u) of(0.01–0.06) mol kg�1 B.HCl drug in (0.10, 0.20 and 0.30) molkg�1aqueous NaCl and KCl solutions have been measured as afunction of temperature at T = (293.15, 298.15, 303.15, 308.15 and313.15) K and at atmospheric pressure. Results are interpreted interms of ion–ion, hydrophilic-ionic, ion-hydrophobic, electrostaticinteractions and structure making/breaking ability of B.HCl drug inaqueous NaCl and KCl solutions. To the best of our knowledge,densities and speeds of sound of B.HCl drug in aqueous NaCl andKCl solutions are not reported in the literature.
2. Experimental
2.1. Chemicals
For the investigation of thermophysical properties of B.HCldrug in aqueous NaCl and KCl solutions, the following chemicalshave been used; betaine hydrochloride were obtained from Sigma–Aldrich Co. and the structure of B.HCl drug shown in Scheme 1,sodium chloride supplied by Himedia Laboratory, potassium
Scheme 1. Structure of betaine hydrochloride.
Table 1Specifications of the chemicals used in this work.
Compounda Mass fractionpurity
CAS no. Source Purificationmethod
Betaine HCl �0.99 590-46-5
Sigma–AldrichCo.
None
NaCl �0.99 7647-14-5
Himedialaboratory
None
KCl �0.99 7447-40-7
Merckchemicals
None
a Used as received from source, without further purification.
72 S. Ryshetti et al. / Thermochimica Acta 597 (2014) 71–77
chloride have been received from Merck Chemicals. All thecompounds were of �0.99 mass fraction purity and were usedafter drying over P2O5 in vacuum desiccators at room temperaturefor 48 h. The details of the chemical compounds used in this workare shown in the Table 1.
2.2. Equipment and procedure
The aqueous solutions were prepared by using the doublydistilled, degassed water with a specific conductance less than1 �10�6 S cm�1 at 298.15 K. All aqueous solutions were made atroom temperature on the mass basis over a concentration range(0.01–0.06) mol kg�1 and these solutions kept in airtight bottles toavoid contamination of air and moisture. The weighting wasperformed by using an electronic analytical balance (Sartorius,Model CPA225D) with a precision of �0.01 mg. The densities (r)and speeds of sound (u) have been measured using Anton Paar DSA5000M instrument on the same day of sample preparation. Theinstrument was calibrated with doubly distilled water and dry airat the investigated temperatures; uncertainty in the measure-ments of density (r) and speed of sound at 3 MHz frequency are (u)is �5 �10�3 kg m�3 and �0.5 m s�1, respectively. The experimentswere carried out at T = (293.15, 298.15, 303.15, 308.15 and 313.15) Kwith an accuracy of �0.01 K. The temperature was controlled by aPeltier thermostat (PT 100) which is in-built on Anton Paar DSA5000M instrument [13]. The instrument was calibrated withdoubly distilled freshly degassed water and dry air in frequentintervals of time. Details about instrument calibration andmeasurement procedures are explained in our recent work [14].
Table 2Densities (r) and apparent molar volumes (V2,f) of B.HCl inaqueous NaCl and KCl solu
m/(mol kg�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
293.15 K 298.15 K 303.15 K
(B.HCl + 0.10 mol kg�1NaCl)0 1.00242 1.00121 0.99977
0.00949 1.00275 118.59 1.00153 119.12 1.00009
0.01968 1.00309 118.87 1.00188 119.38 1.00043
0.02922 1.00342 119.09 1.00219 119.61 1.00074
0.03906 1.00374 119.37 1.00252 119.86 1.00106
0.05026 1.0041 119.63 1.00287 120.16 1.00141
0.05896 1.00438 119.84 1.00315 120.4 1.00168
(B.HCl + 0.20 mol kg�1NaCl)0 1.00667 1.00541 1.00393
0.00968 1.007 118.93 1.00573 119.54 1.00425
0.02043 1.00736 119.28 1.00609 119.82 1.0046
0.02942 1.00765 119.47 1.00638 120.01 1.00489
0.03792 1.00793 119.66 1.00665 120.26 1.00516
0.04799 1.00825 119.85 1.00697 120.46 1.00547
0.05952 1.00862 120.1 1.00732 120.76 1.00582
(B.HCl + 0.30 mol kg�1 NaCl)0 1.01064 1.00934 1.00781
0.0097 1.01096 119.46 1.00965 119.97 1.00813
0.02097 1.01133 119.7 1.01002 120.28 1.00848
0.03052 1.01163 119.92 1.01032 120.55 1.00878
0.04055 1.01195 120.21 1.01063 120.83 1.00908
0.04969 1.01223 120.49 1.0109 121.04 1.00936
0.06009 1.01254 120.73 1.01121 121.34 1.00966
The standard uncertainties (u) of molalities, density, speed ofsound, temperature and pressure are shown in respective table as afoot notes. Doubly distilled freshly degassed water is used for thepreparation of binary mixtures and water + salt solution is used forthe preparation of ternary mixtures.
3. Results and discussion
3.1. Partial molar properties
The experimental results of densities (r) and speeds of sound(u) for B.HCl drug in aqueous NaCl/KCl solutions are presented inTables 2 and 3, respectively. Experimentally measured density, rand speed of sound, u of aqueous NaCl and aqueous KCl solutionsare in good agreement with the corresponding available literaturevalues as presented in Supporting material (Table S1 and Figs. S1and S2). It can be seen from Tables 2 and 3, the values of density (r)and speed of sound (u) are varying with temperature, compositionsof cosolute and solute at a given pressure, which furnish the effectof temperature and composition of additives on the solvationbehavior of solute in probed solutions. Furthermore, the apparentmolar volumes (V2,f) and apparent molar isentropic compress-ibility (Ks,2,f) for ternary mixtures are calculated from thedensities (r) and speeds of sound (u) of solutions by using Eqs.(1) and (2), respectively.
tions at T = (293.15–313.15) K and pressure p = 0.1 MPa.a
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
308.15 K 313.15 K
0.99812 0.99628119.77 0.99844 120.33 0.99659 121.02120.01 0.99877 120.56 0.99693 121.13120.24 0.99908 120.77 0.99723 121.34120.47 0.9994 121.03 0.99754 121.58120.76 0.99974 121.31 0.99788 121.87120.98 1.00001 121.56 0.99815 122.1
1.00225 1.00038120.18 1.00257 120.74 1.00069 121.42120.39 1.00291 120.92 1.00103 121.53120.58 1.0032 121.1 1.00131 121.71120.76 1.00346 121.25 1.00158 121.92120.98 1.00377 121.48 1.00188 122.11121.31 1.00412 121.83 1.00222 122.42
1.0061 1.0042120.62 1.00641 121.07 1.00451 121.75120.93 1.00676 121.42 1.00485 122.11121.17 1.00705 121.65 1.00514 122.28121.43 1.00736 121.9 1.00544 122.49121.68 1.00762 122.17 1.0057 122.79121.9 1.00793 122.42 1.006 123.03
Table 2 (Continued)
m/(mol kg�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
r � 10�3/(kg m�3)
V2,f�106/(m3 mol�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
(B.HCl + 0.10 mol kg�1KCl)0 1.00299 1.00179 1.00036 0.99871 0.996880.00891 1.00331 117.97 1.0021 118.41 1.00067 119.09 0.99902 119.56 0.99718 120.290.01924 1.00366 118.25 1.00245 118.82 1.00101 119.41 0.99936 119.91 0.99752 120.590.02749 1.00395 118.51 1.00273 119.08 1.00129 119.67 0.99963 120.18 0.99778 120.780.03999 1.00436 118.91 1.00314 119.46 1.00169 120.04 1.00003 120.56 0.99818 121.170.04956 1.00467 119.22 1.00345 119.8 1.002 120.35 1.00033 120.82 0.99847 121.490.05943 1.00499 119.55 1.00376 120.07 1.0023 120.65 1.00064 121.12 0.99877 121.76
(B.HCl + 0.20 mol kg�1KCl)0 1.00772 1.00648 1.00502 1.00335 1.001490.00888 1.00803 118.37 1.00678 118.92 1.00532 119.49 1.00365 119.97 1.00178 120.690.01993 1.0084 118.65 1.00715 119.2 1.00568 119.82 1.00401 120.27 1.00214 120.930.02938 1.00872 118.87 1.00746 119.45 1.00599 120.04 1.00431 120.49 1.00244 121.130.04163 1.00912 119.27 1.00786 119.83 1.00638 120.38 1.0047 120.84 1.00282 121.490.04853 1.00934 119.47 1.00807 120.03 1.00659 120.58 1.00491 121.04 1.00303 121.640.05846 1.00964 119.89 1.00837 120.41 1.00689 120.98 1.0052 121.42 1.00332 122.01
(B.HCl + 0.30 mol kg�1 KCl)0 1.01342 1.01213 1.01063 1.00894 1.007020.0099 1.01375 118.59 1.01246 119.1 1.01095 119.82 1.00926 120.26 1.00734 120.930.01907 1.01406 118.98 1.01276 119.45 1.01125 120.04 1.00955 120.55 1.00763 121.190.02932 1.01439 119.28 1.01308 119.76 1.01157 120.36 1.00987 120.84 1.00794 121.420.03865 1.01468 119.61 1.01338 120.05 1.01186 120.64 1.01016 121.09 1.00823 121.70.04616 1.01491 119.84 1.01361 120.29 1.01209 120.79 1.01038 121.34 1.00845 121.88
a Standard uncertainties u are u (m) = 2 � 10�5mol kg�1,u (r) = 5 �10�3 kg m�3, u (T) = 0.01 K and u (p) = 0.01 MPa. m is molality of betaine hydrochloride in per kg of water or(water + salt) mixture. Molality of salts in per kg of water is prepared with standard uncertainty of 3 � 10�5mol kg�1.
Table 3Speed of sound (u) and apparent molar isentropic compressibilities (Ks,2,f) of B.HCl in aqueous NaCl and KCl solutions at T = (293.15–313.15) K and pressure p = 0.1 MPa.a
m/(mol kg�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1 GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1 GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1 GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1GPa�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
(B.HCl + 0.10 mol kg�1NaCl)0 1489.33 1503.31 1515.48 1525.88 1534.760.00949 1490.35 �26.98 1504.32 �25 1516.48 �23.16 1526.86 �21.01 1535.72 �18.930.01968 1491.44 �26.57 1505.38 �24.04 1517.53 �22.25 1527.9 �20.46 1536.75 �18.820.02922 1492.43 �25.67 1506.32 �22.55 1518.5 �21.56 1528.82 �19.12 1537.65 �17.390.03906 1493.41 �24.42 1507.31 �21.95 1519.46 �20.51 1529.76 �18.16 1538.53 �15.860.05026 1494.5 �23.21 1508.43 �21.36 1520.49 �18.98 1530.85 �17.66 1539.62 �15.690.05896 1495.29 �21.95 1509.23 �20.28 1521.19 �17.16 1531.59 �16.29 1540.35 �14.45
(B.HCl + 0.20 mol kg�1NaCl)0 1496.19 1509.89 1521.8 1532.03 1540.670.00968 1497.24 �26.04 1510.92 �23.47 1522.83 �22.3 1533.03 �19.67 1541.66 �18.250.02043 1498.43 �26.43 1512.07 �23.41 1523.93 �20.93 1534.12 �18.97 1542.7 �16.590.02942 1499.37 �25.33 1512.99 �22.46 1524.86 �20.61 1534.99 �17.88 1543.53 �15.260.03792 1500.22 �24.07 1513.82 �21.24 1525.7 �19.79 1535.75 �16.35 1544.34 �14.840.04799 1501.22 �23.04 1514.78 �20.07 1526.59 �17.9 1536.72 �15.95 1545.26 �14.060.05952 1502.3 �21.53 1515.89 �19.16 1527.67 �16.93 1537.69 �14.19 1546.25 �12.76
(B.HCl + 0.30 mol kg�1 NaCl)0 1502.35 1515.8 1527.55 1537.63 1546.230.0097 1503.42 �25.57 1516.84 �22.57 1528.59 �21.45 1538.64 �18.96 1547.22 �17.030.02097 1504.65 �24.97 1518.02 �21.53 1529.79 �20.94 1539.76 �17.28 1548.36 �16.460.03052 1505.63 �23.5 1519 �20.72 1530.74 �19.47 1540.69 �16.37 1549.27 �15.270.04055 1506.69 �22.98 1520.01 �19.89 1531.7 �18.04 1541.67 �15.81 1550.26 �14.970.04969 1507.59 �21.82 1520.89 �18.93 1532.64 �17.88 1542.51 �14.82 1551.08 �13.780.06009 1508.56 �20.39 1521.83 �17.5 1533.59 �16.62 1543.44 �13.78 1551.99 �12.63
(B.HCl + 0.10 mol kg�1 KCl)0 1488.5 1502.45 1514.56 1525.09 1534.020.00891 1489.46 �27.68 1503.4 �25.72 1515.51 �24.44 1526.02 �22.26 1534.93 �20.060.01924 1490.55 �26.68 1504.48 �24.68 1516.61 �24.11 1527.09 �21.7 1536 �20.220.02749 1491.4 �25.8 1505.34 �24.22 1517.46 �23.25 1527.95 �21.51 1536.81 �19.260.03999 1492.68 �24.84 1506.65 �23.8 1518.73 �22.22 1529.18 �20.18 1538.09 �19.080.04956 1493.63 �23.94 1507.66 �23.54 1519.75 �22.19 1530.19 �20.3 1538.98 �17.860.05943 1494.58 �22.91 1508.61 �22.43 1520.78 �21.88 1531.18 �19.79 1539.92 �17.18
(B.HCl + 0.20 mol kg�1 KCl)0 1493.78 1507.35 1519.28 1529.6 1538.42
S. Ryshetti et al. / Thermochimica Acta 597 (2014) 71–77 73
Table 3 (Continued)
m/(mol kg�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1GPa�1)
u/(m s�1)
Ks,2,f�106/(m3mol�1 GPa�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
0.00888 1494.74 �26.34 1508.3 �24.37 1520.23 �23.24 1530.53 �21.11 1539.33 �18.960.01993 1495.94 �26.27 1509.5 �24.65 1521.39 �22.34 1531.66 �20.12 1540.44 �18.170.02938 1496.93 �25.35 1510.48 �23.63 1522.35 �21.35 1532.61 �19.39 1541.39 �17.830.04163 1498.14 �23.53 1511.79 �23.36 1523.59 �20.51 1533.86 �19.03 1542.64 �17.680.04853 1498.78 �22.34 1512.49 �22.75 1524.3 �20.28 1534.56 �18.79 1543.29 �16.990.05846 1499.8 �21.92 1513.53 �22.29 1525.27 �19.38 1535.58 �18.5 1544.22 �16.05
(B.HCl + 0.30 mol kg�1 KCl)0 1497.6 1510.98 1522.76 1532.93 1541.640.0099 1498.69 �26.14 1512.06 �24.32 1523.83 �22.52 1533.97 �20.05 1542.66 �18.120.01907 1499.71 �26.09 1513.04 �23.39 1524.81 �21.99 1534.92 �19.41 1543.58 �17.20.02932 1500.78 �24.56 1514.15 �23.17 1525.89 �21.3 1535.94 �18.24 1544.63 �17.140.03865 1501.75 �23.63 1515.1 �22.05 1526.84 �20.4 1536.9 �18.05 1545.56 �16.60.04616 1502.46 �22.22 1515.89 �21.71 1527.62 �20.11 1537.65 �17.59 1546.25 �15.62
a Standard uncertainties u are u (m) = 2 � 10�5mol kg�1, u (u) = 0.5 m s�1, u (T) = 0.01 K and u (p) = 0.01 MPa. m is molality of betaine hydrochloride in per kg of water or(water + salt) mixture. Molality of salts in per kg of water is prepared with standard uncertainty of 3 � 10�5mol kg�1.
74 S. Ryshetti et al. / Thermochimica Acta 597 (2014) 71–77
V2;f ¼ Mr� 1000ðr � roÞ
mrro(1)
Ks;2;f ¼ ksMr
� 1000 kosr � ksro
� �mrro
(2)
where M and m are molar mass and molality of B.HCl drug, r and ro
are the densities of solution and solvent, ks and kso are the
isentropic compressibilities of solution and solvent, respectively.Isentropic compressibilities (ks) are evaluated from the values ofdensity (r) and speed of sound (u) by using the following relation:
ks ¼ 1u2r
(3)
In the present work, it is evident from the Tables 2 and 3, thevalues of V2,f and Ks,2,f increases with increase in temperature,concentrations of solute and cosolute; this suggests the increasingof solute–solvent interactions along with raise in temperature ofthe solution and composition of the solute/cosolute, Pal andChauhan [15] and Nain et al. [16] also observed similar results forother ternary systems. The variation of apparent molar volume
118
119
120
121
122
123
0.00 0.0 2 0.0 4 0.06
V2,φ.106/(m
3 .mol-1)
m/(mol. kg-1)
Fig. 1. Plot of apparent molar volumes (V2,f) versus molality (m) of B.HCl drug inaqueous 0.10 mol dm�3 NaCl solution at temperatures, T = ^, 293.15 K; &, 298.15 K;~, 303.15 K; �, 308.15 K; *, 313.15 K.
(V2,f) with molality (m) of B.HCl drug in aqueous NaCl solution atdifferent temperatures is represented in Fig. 1. The concentrationdependence of V2,f and Ks,2,f values at a given temperature andpressure have been measured by the Eq. (4) and (5), respectively.
V2;f ¼ V12 þ Sv � m (4)
Ks;2;f ¼ K1s;2 þ Sk � m (5)
here Sv and Sk are the experimental or limiting slopes which areaccountable for the solute–solute interactions. The Sv and Sk arealso known as semi-empirical parameters which depends onsolvent, solute, and temperature of the solution; for non-electrolytic solutes the values of Sv and Sk are not of muchsignificance [17]. The solute–solvent interactions at infinitedilutions can be analyzed by the values of V2
1 and Ks,21, and
these values (along with standard deviations) are reported inTables 4 and 5, respectively. In the present investigation, thepositive values of V2
1 or negative values of Ks,21 indicates the
presence of strong solute–solvent interactions between B.HCl drugand water or (water + NaCl/KCl) at all the investigated composi-tions and temperatures. The values of V2
1 and Ks,21 are increased
with increase in temperature which may be due to the results ofreleasing of water molecules from the second solvation layer of
Table 4Partial molar volumes (V2
1) of B.HCl in aqueous NaCl and KCl solutions atT = (293.15–313.15) K and pressure p = 0.1 MPa.a
V21�106/(m3mol�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
B.HCl + 0.10 mol kg�1 NaCl 118.37 118.86 119.52 120.07 120.73�0.01 �0.01 �0.01 �0.02 �0.05
B.HCl + 0.20 mol kg�1 NaCl 118.77 119.32 119.94 120.49 121.16�0.04 �0.02 �0.03 �0.05 �0.05
B.HCl + 0.30 mol kg�1 NaCl 119.17 119.72 120.38 120.83 121.53�0.03 �0.01 �0.02 �0.02 �0.04
B.HCl + 0.10 mol kg�1 KCl 117.66 118.16 118.81 119.32 120.01�0.02 �0.03 �0.01 �0.02 �0.02
B.HCl + 0.20 mol kg�1KCl 118.04 118.61 119.21 119.68 120.41�0.06 �0.04 �0.05 �0.04 �0.05
B.HCl + 0.30 mol kg�1 KCl 118.31 118.82 119.54 119.98 120.66�0.03 �0.03 �0.02 �0.01 �0.02
Molality of salts in per kg of water is prepared with standard uncertainty of3 � 10�5mol kg�1.
a Standard uncertainties u are u (T) = 0.01 K and u (p) = 0.01 MPa.
Table 5Partial molar isentropic compressibilities (Ks,2
1) of B.HCl in aqueous NaCl and KClsolutions at T = (293.15–313.15) K and pressure p = 0.1 MPa.a
Ks,21� 106/(m3mol�1GPa�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
B.HCl + 0.10 mol kg�1NaCl �28.4 �25.7 �24.63 �22.02 �20.13�0.30 �0.28 �0.42 �0.26 �0.42
B.HCl + 0.20 mol kg�1NaCl �27.81 �24.91 �23.44 �20.97 �18.86�0.55 �0.38 �0.35 �0.31 �0.34
B.HCl + 0.30 mol kg�1NaCl �26.83 �23.63 �22.58 �19.61 �18.09�0.29 �0.19 �0.35 �0.24 �0.27
B.HCl + 0.10 mol kg�1KCl �28.47 �26 �24.89 �22.68 �21.01�0.26 �0.25 �0.28 �0.25 �0.36
B.HCl + 0.20 mol kg�1KCl �27.83 �25.12 �23.81 �21.24 �19.41�0.49 �0.29 �0.15 �0.26 �0.27
B.HCl + 0.30 mol kg�1KCl �27.45 �24.72 �23.31 �20.77 �19.12�0.45 �0.29 �0.11 �0.24 �0.49
a Standard uncertainties u are u (T) = 0.01 K and u (p) = 0.01 MPa. Molality of saltsin per kg of water is prepared with standard uncertainty of 3 � 10�5mol kg�1.
Table 6Transfer partial molar volumes (DtV2
1) of B.HCl in aqueous NaCl and KCl solutionsat T = (293.15–313.15) K and pressure p = 0.1 MPa.a
DtV21�106/(m3mol�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
B.HCl + 0.10 mol kg�1 NaCl 2.82 2.9 3 3.16 3.25B.HCl + 0.20 mol kg�1 NaCl 3.22 3.35 3.42 3.58 3.67B.HCl + 0.30 mol kg�1 NaCl 3.63 3.76 3.86 3.93 4.05B.HCl + 0.10 mol kg�1 KCl 2.12 2.2 2.29 2.41 2.53B.HCl + 0.20 mol kg�1 KCl 2.5 2.65 2.69 2.78 2.92B.HCl + 0.30 mol kg�1 KCl 2.77 2.86 3.02 3.08 3.17
Molality of salts in per kg of water is prepared with standard uncertainty of3 � 10�5mol kg�1.
a Standard uncertainties u are u (T) = 0.01 K and u (p) = 0.01 MPa.
S. Ryshetti et al. / Thermochimica Acta 597 (2014) 71–77 75
solute in water as well as in aqueous NaCl and KCl solutions[18–20]. The plot of partial molar volumes (V2
1) versus tempera-ture (T) for B.HCl drug in aqueous NaCl solutions is shown in Fig. 2,similar behavior was also observed for B.HCl drug in aqueous KClsolutions with rise in temperature. The concentrations of thecosolute are also having the notable impact on the values ofV2
1and Ks,21, this can be inferred from the increasing values of V2
1
and Ks,21 with increasing molalities of the NaCl and KCl. For the
studied systems, higher values of V21 and Ks,2
1 in aqueous NaClsolutions suggest that the mixtures with aqueous NaCl solutionsare having strong solute–solvent interactions compare to thesystems (B.HCl+ aqueous KCl solutions). Thus, studied experimen-tal properties along with derived thermodynamic properties areuseful to understand the effects of experimental temperature andcompositions on the molecular interactions of B.HCl drug inaqueous NaCl and KCl solutions. Furthermore, these molecularinteractions can be interpreted on the basis of cosphere overlapmodel which is developed by Gurney, Frank and Evans [21–23].According to this model solute–solvent interactions can beclassified as: (i) ionic/hydrophilic-ionic interactions between theionic (—N+(CH3)3/Cl�)/hydrophilic (—COOH) groups of B.HCl drugand ions of NaCl/KCl and (ii) hydrophobic-ionic interactionsbetween the —CH2 groups of B.HCl drug and ions of NaCl/KCl.
118
119
120
121
122
288.15 298.15 308.15 318.15
V2∞.10
6 /(m3 .mol-1)
T/K
Fig. 2. Plot of partial molar volumes (V21) versus temperature (T) for: &, B.HCl
drug + 0.10 mol kg�1 NaCl; ^, B.HCl drug + 0.20 mol kg�1 NaCl; ~, B.HCl drug + 0.30mol kg�1 NaCl.
3.2. Transfer partial molar properties
The values of transfer partial molar volume (DtV21) and
transfer partial molar compressibility (DtKs,21) are having signifi-
cant role in analyzing the solute–solvent interactions [24]. Thevalues of DtV2
1 and DtKs,21 can be obtained from the following
Eq. (6) and are given in Table 6 and 7, respectively.
DtX12 ¼ X1
2in aqueous glycineL � prolinesolutions
� �� X1
2 inwaterð Þ (6)
here DtX21 = (DtV2
1 or DtKs,21), X2
1 = (V21 or Ks,2
1). According tocosphere overlap model, the positive values of DtX2
1 areresponsible for ionic/hydrophilic-ionic interactions (first type)and the negative values of DtX2
1 are accountable for hydrophobic-ionic interactions (second type). In the present work, the positivevalues of DtX2
1 indicate the presence of ionic/hydrophilic-ionicinteractions in (B.HCl drug + aqueous NaCl/KCl solutions). Thevalues of DtX2
1 are increasing with increase in the temperaturewhich may be due to increasing of dehydration around the ionic(—N+(CH3)3/Cl�)/hydrophilic (—COOH) groups of B.HCl drug. Theincreasing concentrations of cosolute are responsible for the ionic/hydrophilic-ionic interactions over hydrophobic-ionic interactions[25–27], and this behavior is more favorable in aqueous NaClsolutions compare to aqueous KCl solutions, suggested by thehigher positive values of DtX2
1 in aqueous NaCl solutions thanaqueous KCl solutions. These results indicate the increasing of B.HCl drug–solvent interactions by the addition of cosolute andincreasing temperature.
The values of V21 can be analyzed by using Shahidi’s equation
[28,29], which provides the valuable information regardingelectrostricted water molecules around the ionic (—N+(CH3)3/Cl�)/hydrophilic (—COOH) groups of B.HCl drug.
Table 7Transfer partial molar isentropic compressibilities (DtKs,2
1) of B.HCl in aqueousNaCl and KCl solutions at T = (293.15–313.15) K and pressure p = 0.1 MPa.a
DtKs,21� 106/(kg m3mol�2GPa�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
B.HCl + 0.10 mol kg�1 NaCl 1.15 1.4 1.53 1.99 2.48B.HCl + 0.20 mol kg�1 NaCl 1.75 2.2 2.72 3.05 3.76B.HCl + 0.30 mol kg�1 NaCl 2.73 3.48 3.59 4.41 4.53B.HCl + 0.10 mol kg�1 KCl 1.09 1.11 1.27 1.33 1.61B.HCl + 0.20 mol kg�1 KCl 1.72 1.99 2.35 2.78 3.21B.HCl + 0.30 mol kg�1 KCl 2.1 2.39 2.85 3.24 3.5
a Standard uncertainties u are u (T) = 0.01 K and u (p) = 0.01 MPa. Molality of saltsin per kg of water is prepared with standard uncertainty of 3 �10�5mol kg�1.
Table 8Partial molar expansions (E21) of B.HCl in aqueous NaCl and KCl solutions at T = (293.15–313.15) K and pressure p = 0.1 MPa.a
E21� 106/(m3mol�1 K�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K
B.HCl + 0.10 mol kg�1 NaCl 0.107 0.113 0.119 0.125 0.131B.HCl + 0.20 mol kg�1 NaCl 0.11 0.114 0.119 0.124 0.128B.HCl + 0.30 mol kg�1 NaCl 0.111 0.114 0.117 0.119 0.122B.HCl + 0.10 mol kg�1 KCl 0.103 0.11 0.117 0.124 0.132B.HCl + 0.20 mol kg�1 KCl 0.106 0.111 0.116 0.121 0.127B.HCl + 0.30 mol kg�1 KCl 0.114 0.115 0.117 0.119 0.12
Molality of salts in per kg of water is prepared with standard uncertainty of 3 � 10�5mol kg�1.a Standard uncertainties u are u (T) = 0.01 K and u (p) = 0.01 MPa.
Table 9The values of (@Cp,21/@P)T and (@2V2
1/@T2)P of B.HCl drug in aqueous NaCl and KCl solutions at T = (293.15–313.15) K and pressure p = 0.1 MPa.a
(@Cp,21/@P)T/(cm3mol�2 K�1)
293.15 K 298.15 K 303.15 K 308.15 K 313.15 K (@2V21/@T2)P/(cm6mol�2 K�2)
B.HCl + 0.10 mol kg�1 NaCl �0.352 �0.358 �0.364 �0.37 �0.376 0.0012B.HCl + 0.20 mol kg�1 NaCl �0.272 �0.277 �0.281 �0.286 �0.291 0.0009B.HCl + 0.30 mol kg�1 NaCl �0.153 �0.155 �0.158 �0.161 �0.163 0.0005B.HCl + 0.10 mol kg�1 KCl �0.419 �0.427 �0.434 �0.441 �0.448 0.0014B.HCl + 0.20 mol kg�1 KCl �0.309 �0.314 �0.32 �0.325 �0.33 0.0011B.HCl + 0.30 mol kg�1KCl �0.092 �0.094 �0.096 �0.097 �0.099 0.0003
Molality of salts in per kg of water is prepared with standard uncertainty of 3 � 10�5mol kg�1.a Standard uncertainties u are u (T) = 0.01 K and u (p) = 0.01 MPa.
76 S. Ryshetti et al. / Thermochimica Acta 597 (2014) 71–77
V12 ¼ Vvw þ Vvoid � Vshrinkage (7)
where Vvw is the van der Waal’s volume, Vvoid is the volumeassociated with voids and Vshrinkage is the shrinkage volume due toelectrostriction of the solvents induced by the ionic (—N+(CH3)3/Cl�)/hydrophilic (—COOH) groups of B.HCl drug. In this presentstudy, Vvw and Vvoid are assumed to be constant in investigatedsolutions [12]. The positive values of DtV2
1 indicate decrees inVshrinkage in presence of cosolute [30]. The values of Vshrinkage aredecreasing with the increase in temperature and concentration ofNaCl and KCl. The extent of this decrement in Vshrinkage is more incase of aqueous NaCl solutions than aqueous KCl solutions, mainlydue to higher values of DtV2
1 in aqueous NaCl solutions.
3.3. Partial molar expansion
The temperature dependence of partial molar volume (V21) for
B.HCl drug in aqueous NaCl/KCl solutions can be determined by thefollowing expression.
V12 ¼ a0 þ a1T þ a2T
2 (8)
where T is the temperature in Kelvin. The values of coefficients a0,a1 and a2 have been estimated by the least-squares fitting of thevalues of V2
1 in Eq. (8). The partial molar expansion (E21) can bedetermined by differentiating Eq. (8) with respect to temperature.
E12 ¼ @V12
@T
� �P¼ a1 þ 2a2T (9)
The positive E21 values (Table 8) indicates the presence of strong
solute–solvent interactions in all investigated solutions, furtherthese solute–solvent interactions increases with increasing tem-perature at all compositions of NaCl and KCl, Roy et al. [31] also
observed the increasing E21 values along with increasing
temperature in a ternary mixture.The structure making/breaking capacity of B.HCl drug in
aqueous NaCl and KCl solutions can be interpreted by the Hepler’sequation [32].
@C1p;2
@P
!T
¼ �T@2V1
2
@T2
!(10)
Hepler suggested that the positive values of (@2V21/@T2)P (or
negative values of ((@Cp,21/@P)T) and negative values of (@2V21/
@T2)P (or positive values of (@Cp,21/@P)T) are responsible for thestructure making and structure breaking nature of solutemolecules in solutions, respectively [32]. In the present study(Table 9), the positive values of (@2V2
1/@T2)P indicate structuremaking effect of B.HCl drug in aqueous NaCl and KCl solutions andstructure making nature increases with increasing the concen-trations of NaCl and KCl.
4. Conclusions
In the present work, the apparent molar volume, partial molarvolume, transfer partial molar volume, partial molar expansionand Hepler’s constant and so on are calculated from theexperimental values of densities and speed of sound of betainehydrochloride (B.HCl) drug (0.01–0.06) mol kg�1 in (0.10, 0.20 and0.30) mol kg�1aqueous NaCl and KCl solutions at various temper-atures from 293.15 to 313.15 K. These derived thermodynamicproperties indicated the presence of ionic/hydrophilic-ionicinteractions between B.HCl drug and ions of NaCl and KCl. Theseparameters are important to understand the temperature, con-centrations of solute and cosolute effects on B.HCl drug–solventinteractions. The decrease in electrostriction of water moleculesaround the ionic/hydrophilic groups of B.HCl drug has been noticedwith raising temperature and concentration of NaCl and KCl. The
S. Ryshetti et al. / Thermochimica Acta 597 (2014) 71–77 77
sign and magnitude of the Hepler’s constant indicates the structuremaking ability of B.HCl drug in aqueous NaCl and KCl solutions. TheB.HCl drug–solvent interactions in ternary mixtures (B.HCl drug +NaCl/KCl + H2O) are significantly affected by the temperature,compositions of solute and cosolute.
Acknowledgments
Suresh Ryshetti and Bharath Kumar Chennuri are thankful toUniversity Grants Commission (UGC), Government of India, for thefinancial support in the form of Junior Research Fellowship (JRF).Authors are thankful to Council of Scientific and IndustrialResearch (CSIR) and Department of Science and Technology(DST), India, for their financial support.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, inthe online version, at http://dx.doi.org/10.1016/j.tca.2014.10.019.
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