The experimental determinate values of density (ρ), viscosity (η) and sound velocity (u) of all the pure liquids at 303.15 K are presented in Table 1 and the same for the six binary systems are listed in Table 2. The excess value of viscosity (\({\eta }^{E}\)), sound velocity (\({u}^{E}\)), free volume (\({V}_{f}^{E}\)) and internal pressure (\({p}_{i}^{E}\)) at 303.15 K are reported in Table 3. The result present in Table 2 show non-linear behavior of viscosity, sound velocity, free volume and internal pressure, which is further substantial by their excess values (Table 3). All the seven organic compounds namely 1,4-dioxane, methanol, ethanol, propanol, butanol, hexanol and octanol are a polar organic compounds having dipole moment 0.45 D, 1.70 D, 1.69 D, 1.68 D, 1.66 D, 1.60 D and 1.68 D respectively. Normally more the dipole moment, stronger is the intermolecular interaction, which result is decreasing of free space between molecules and increase in the ultrasonic velocity.
The measured values density (ρ), viscosity (η) and sound velocity (u) and the evaluated parameters are presented in Table 2. For the binary system 1,4-dioxane + methanol, 1,4-dioxane + ethanol, 1,4-dioxane + propanol, 1,4-dioxane + butanol, 1,4-dioxane + hexanol and 1,4-dioxane + octanol at 303.15 K. From Tables it can be noticed that, at the 303.15 K temperature the value of sound velocity, viscosity and free volume increase with increase in mole fraction of 1,4-dioxane (\({x}_{1}\)) but the value of density (ρ) and internal pressure decrease with increase in mole fraction of 1,4-dioxane (\({x}_{1}\)). It is evident that the pronounced increase or decrease in these parameters with composition of mixtures indicates the presence of interaction between the component molecules in the binary mixtures. This trend indicates specific interactions among the constituents of the mixtures. This behavior can be attributed to intermolecular interaction [16–37]. The chemical interaction may involve the association due to hydrogen bonding order to dipole-dipole interaction or may be due to the formation of charge-transfer complexes. All these process may lead to strong interaction forces [38].
An analysis of the viscosity values from the Table 2 it can be observed that the viscosity is in decrease trend with increase in mole fraction of 1,4-dioxane. Similar trend is also observed for the internal pressure values. This kind of non-linearity indicates the presence of molecular interactions.
It is observed that for the binary liquid mixtures, the density (ρ) and free volume (\({V}_{f}\)) increase with increase in concentration of 1,4-dioxane. The increases the density (ρ) and free volume (\({V}_{f}\)) in these liquid mixtures suggest that molecular interaction among the molecules of the components of liquid mixture.
Table 2
Values of density, sound velocity, viscosity, free volume and internal pressure properties for binary liquids mixtures of 1,4-dioxane + 1-methanol, 1,4-dioxane + 1-ethanol, 1,4-dioxane + 1- propanol, 1,4-dioxane + 1-butanol, 1,4-dioxane + 1-hexanol and 1,4-dioxane + 1-octanol at 303.15 K
Mole fraction of 1,4-dioxane
(\({X}_{1}\))
|
Density
(ρ )
g.m− 3
|
Sound velocity
( u )
m.s− 1
|
Viscosity
(η)
cp
|
Free volume
(\({V}_{f}\))
ml mol-1
|
Internal pressure
(\({p}_{i}\)×\({10}^{4}\))
atm.
|
1,4-Dioxane + 1-Methanol
|
0.00000
|
0.7840
|
1084.0
|
0.4949
|
0.06639
|
1.85827
|
0.09770
|
0.82748
|
1092.0
|
0.5704
|
0.06873
|
1.55867
|
0.20043
|
0.86692
|
1130.0
|
0.6005
|
0.08297
|
1.29924
|
0.28674
|
0.89696
|
1155.0
|
0.6339
|
0.09268
|
1.13200
|
0.38010
|
0.91716
|
1176.0
|
0.6703
|
0.10226
|
0.98575
|
0.49857
|
0.94224
|
1240.0
|
0.7168
|
0.11938
|
0.83121
|
0.59198
|
0.96312
|
1266.0
|
0.7802
|
0.12298
|
0.75747
|
0.70860
|
0.98772
|
1289.0
|
0.8441
|
0.12956
|
0.67723
|
0.80020
|
0.99876
|
1306.0
|
0.9426
|
0.12420
|
0.63839
|
0.90362
|
1.00892
|
1330.0
|
1.0244
|
0.12564
|
0.58824
|
1.00000
|
1.0108
|
1348.0
|
1.0303
|
0.13976
|
0.52793
|
1,4-Dioxane + 1-Ethanol
|
0.00000
|
0.7720
|
1141.0
|
1.1399
|
0.03536
|
1.48567
|
0.09885
|
0.80944
|
1150.0
|
1.1038
|
0.04274
|
1.33256
|
0.20465
|
0.8426
|
1170.0
|
1.0986
|
0.05016
|
1.17588
|
0.29964
|
0.8652
|
1189.0
|
1.0814
|
0.05849
|
1.02250
|
0.39745
|
0.8990
|
1217.0
|
1.0740
|
0.06775
|
0.92291
|
0.50220
|
0.92016
|
1285.0
|
1.0710
|
0.08167
|
0.81416
|
0.59502
|
0.94108
|
1288.0
|
1.0697
|
0.08941
|
0.75046
|
0.69003
|
0.9720
|
1298.0
|
1.0593
|
0.09964
|
0.69393
|
0.79934
|
0.98624
|
1310.0
|
1.0485
|
0.11215
|
0.62849
|
0.89342
|
0.99356
|
1340.0
|
1.0406
|
0.12619
|
0.57388
|
1.00000
|
1.0108
|
1348.0
|
1.0303
|
0.13976
|
0.52793
|
1,4-Dioxane + 1-Propanol
|
0.00000
|
0.80708
|
1182.0
|
1.5477
|
0.03511
|
1.12536
|
0.10006
|
0.82064
|
1202.0
|
1.4964
|
0.04054
|
1.02842
|
0.12264
|
0.84796
|
1215.0
|
1.2610
|
0.05407
|
0.94383
|
0.29821
|
0.87008
|
1248.0
|
1.1498
|
0.07234
|
0.79892
|
0.40573
|
0.89936
|
1264.0
|
1.1319
|
0.08050
|
0.74945
|
0.50439
|
0.91672
|
1270.0
|
1.1274
|
0.08633
|
0.70945
|
0.60251
|
0.93908
|
1275.0
|
1.1097
|
0.09391
|
0.67187
|
0.69410
|
0.9558
|
1284.0
|
1.0881
|
0.10268
|
0.63513
|
0.79626
|
0.98084
|
1290.0
|
1.0711
|
0.11164
|
0.60302
|
0.89926
|
1.0054
|
1312.0
|
1.0534
|
0.12362
|
0.56923
|
1.00000
|
1.0108
|
1348.0
|
1.0303
|
0.13976
|
0.52793
|
1,4-Dioxane + 1-Butanol
|
0.00000
|
0.8040
|
1196.0
|
2.2045
|
0.02879
|
0.93886
|
0.09734
|
0.8136
|
1203.0
|
1.7804
|
0.04113
|
0.82365
|
0.19759
|
0.84252
|
1209.0
|
1.4627
|
0.05720
|
0.73831
|
0.30443
|
0.86264
|
1221.0
|
1.3458
|
0.06771
|
0.69325
|
0.40480
|
0.87696
|
1268.0
|
1.1934
|
0.08813
|
0.62881
|
0.49442
|
0.90224
|
1282.0
|
1.1939
|
0.09166
|
0.62110
|
0.59768
|
0.92744
|
1287.0
|
1.1879
|
0.09539
|
0.61152
|
0.68628
|
0.95028
|
1297.0
|
1.1044
|
0.11009
|
0.58231
|
0.79076
|
0.97392
|
1315.0
|
1.0953
|
0.11678
|
0.56878
|
0.89091
|
0.99836
|
1334.0
|
1.0728
|
0.12616
|
0.55292
|
1.00000
|
1.0108
|
1348.0
|
1.0303
|
0.13976
|
0.52793
|
1,4-Dioxane + 1-Hexanol
|
0.00000
|
0.8128
|
1298.0
|
4.5642
|
0.01768
|
0.76533
|
0.09108
|
0.83796
|
1302.0
|
3.2904
|
0.02848
|
0.67619
|
0.19485
|
0.85408
|
1311.0
|
2.7369
|
0.03711
|
0.63767
|
0.29842
|
0.86024
|
1314.0
|
2.2727
|
0.04815
|
0.59775
|
0.40439
|
0.88144
|
1320.0
|
1.9013
|
0.06191
|
0.56874
|
0.45430
|
0.88996
|
1334.0
|
1.7643
|
0.06733
|
0.55520
|
0.60286
|
0.92576
|
1338.0
|
1.4365
|
0.09206
|
0.53273
|
0.69974
|
0.9486
|
1340.0
|
1.2914
|
0.10590
|
0.53284
|
0.80182
|
0.9684
|
1342.0
|
1.2103
|
0.11426
|
0.52919
|
0.88834
|
0.99384
|
1346.0
|
1.1144
|
0.12731
|
0.52758
|
1.00000
|
1.0108
|
1348.0
|
1.0303
|
0.13976
|
0.52793
|
1,4-Dioxane + 1-Octanol
|
0.00000
|
0.8242
|
1327.0
|
7.8512
|
0.01166
|
0.66872
|
0.09780
|
0.8284
|
1329.0
|
5.1466
|
0.02098
|
0.57272
|
0.20653
|
0.83708
|
1330.0
|
4.6513
|
0.02313
|
0.58289
|
0.29810
|
0.85292
|
1332.0
|
3.2294
|
0.03818
|
0.51855
|
0.40275
|
0.85956
|
1334.0
|
2.5625
|
0.05113
|
0.49443
|
0.49229
|
0.88528
|
1336.0
|
2.3806
|
0.05439
|
0.51382
|
0.60068
|
0.90304
|
1338.0
|
1.8916
|
0.07220
|
0.49788
|
0.69888
|
0.92664
|
1339.0
|
1.4950
|
0.09686
|
0.48131
|
0.79610
|
0.95648
|
1341.0
|
1.3490
|
0.10643
|
0.49999
|
0.89749
|
0.98596
|
1345.0
|
1.1845
|
0.12142
|
0.51467
|
1.00000
|
1.0108
|
1348.0
|
1.0303
|
0.13976
|
0.52793
|
Table 3
Excess values of sound velocity (\({u}^{E})\), viscosity (\({\eta }^{E}),\)free volume( \({V}_{f}^{E}\)) and internal pressure (\({P}_{i}^{E}\)) properties for binary liquids mixtures of 1,4-dioxane + 1-methanol, 1,4-dioxane + 1-ethanol, 1,4-dioxane + 1-propanol, 1,4-dioxane + 1- butanol, 1,4-dioxane + 1-hexanol and 1,4-dioxane + 1-octanol at 303.15 K.
Mole fraction of 1,4-dioxane
(X1)
|
Excess sound velocity
(\({u}^{E})\)
m.s− 1
|
Excess
Viscosity
(\({\eta }^{E})\)
cp
|
Excess
Free volume \({(V}_{f}^{E}\))
ml mol-1
|
Excess
internal pressure (\({p}_{\text{i}}^{\text{E}} \times {10}^{4}\))
atm.
|
1,4-Dioxane + 1-Methanol
|
0.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
0.09770
|
17.68
|
-0.2075
|
-0.00482
|
-0.16943
|
0.20043
|
16.79
|
-0.2116
|
-0.00500
|
-0.29226
|
0.28674
|
14.58
|
-0.2820
|
-0.00525
|
-0.34470
|
0.38010
|
13.23
|
-0.3650
|
-0.00798
|
-0.36667
|
0.49857
|
12.51
|
-0.4043
|
-0.01641
|
-0.36374
|
0.59198
|
11.85
|
-0.5216
|
-0.01315
|
-0.31323
|
0.70860
|
11.04
|
-0.4523
|
-0.01118
|
-0.23817
|
0.80020
|
10.86
|
-0.3916
|
-0.00889
|
-0.15515
|
0.90362
|
7.56
|
-0.3416
|
-0.00704
|
-0.06757
|
1.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
1,4-Dioxane + 1-Ethanol
|
0.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
0.09885
|
13.43
|
-0.2160
|
-0.00294
|
-0.05836
|
0.20465
|
13.3
|
-0.2215
|
-0.00656
|
-0.11371
|
0.29964
|
13.05
|
-0.2298
|
-0.00814
|
-0.17610
|
0.39745
|
12.96
|
-0.3115
|
-0.00910
|
-0.18209
|
0.50220
|
12.54
|
-0.4160
|
-0.01010
|
-0.19038
|
0.59502
|
11.78
|
-0.4965
|
-0.00806
|
-0.16522
|
0.69003
|
10.58
|
-0.4510
|
-0.00775
|
-0.13077
|
0.79934
|
9.76
|
-0.3920
|
-0.00666
|
-0.09162
|
0.89342
|
8.54
|
-0.2361
|
-0.00244
|
-0.05613
|
1.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
1,4-Dioxane + 1- Propanol
|
0.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
0.10006
|
12.96
|
-0.2165
|
-0.00503
|
-0.03714
|
0.12264
|
12.66
|
-0.2232
|
-0.00613
|
-0.10824
|
0.29821
|
12.51
|
-0.2435
|
-0.00682
|
-0.14826
|
0.40573
|
11.67
|
-0.2858
|
-0.01292
|
-0.13350
|
0.50439
|
11.29
|
-0.3515
|
-0.01456
|
-0.11455
|
0.60251
|
10.97
|
-0.4262
|
-0.01405
|
-0.09351
|
0.69410
|
10.53
|
-0.3004
|
-0.01207
|
-0.07554
|
0.79626
|
9.27
|
-0.2645
|
-0.00680
|
-0.04662
|
0.89926
|
8.54
|
-0.1290
|
-0.00557
|
-0.01831
|
1.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
1,4-Dioxane + 1-Butanol
|
0.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
0.09734
|
11.78
|
-0.3097
|
-0.00153
|
-0.07519
|
0.19759
|
11.02
|
-0.5096
|
-0.00648
|
-0.11934
|
0.30443
|
10.98
|
-0.5211
|
-0.00813
|
-0.12050
|
0.40480
|
10.49
|
-0.5367
|
-0.01241
|
-0.14369
|
0.49442
|
10.25
|
-0.5516
|
-0.01800
|
-0.11458
|
0.59768
|
9.17
|
-0.3147
|
-0.01273
|
-0.08173
|
0.68628
|
8.56
|
-0.2941
|
-0.00913
|
-0.07453
|
0.79076
|
8.18
|
-0.1805
|
-0.00420
|
-0.04512
|
0.89091
|
7.26
|
-0.0855
|
-0.00250
|
-0.01983
|
1.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
1,4-Dioxane + 1-Hexanol
|
0.00000
|
0
|
0.0000
|
0.0000
|
0.00000
|
0.09108
|
10.54
|
-0.9518
|
-0.00032
|
-0.06751
|
0.19485
|
10.28
|
-1.1385
|
-0.00435
|
-0.08139
|
0.29842
|
10.1
|
-1.2368
|
-0.00596
|
-0.09673
|
0.40439
|
9.85
|
-1.2397
|
-0.00614
|
-0.10058
|
0.45430
|
9.36
|
-1.2943
|
-0.00881
|
-0.10227
|
0.60286
|
9.25
|
-1.0971
|
-0.00780
|
-0.08947
|
0.69974
|
8.72
|
-0.9999
|
-0.00279
|
-0.06636
|
0.80182
|
8.52
|
-0.9825
|
-0.00130
|
-0.04578
|
0.88834
|
7.23
|
-0.3103
|
-0.00117
|
-0.02685
|
1.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
1,4-Dioxane + 1-Octanol
|
0.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
0.09780
|
9.04
|
-2.0374
|
-0.00320
|
-0.08222
|
0.20653
|
8.92
|
-2.7911
|
-0.01498
|
-0.05674
|
0.29810
|
8.86
|
-2.9833
|
-0.01526
|
-0.10819
|
0.40275
|
8.54
|
-3.5414
|
-0.01863
|
-0.11758
|
0.49229
|
8.26
|
-3.1126
|
-0.02033
|
-0.08558
|
0.60068
|
8.1
|
-2.8623
|
-0.01641
|
-0.08626
|
0.69888
|
7.66
|
-1.5891
|
-0.01433
|
-0.08901
|
0.79610
|
7.27
|
-1.0720
|
-0.00722
|
-0.05664
|
0.89749
|
7.12
|
-0.5448
|
-0.00522
|
-0.02768
|
1.00000
|
0
|
0.0000
|
0.00000
|
0.00000
|
4.1 Excess Acoustical and Thermodynamic Parameters
The nature of molecular interactions between the components of the liquid mixtures, it is of interest to discuss the same in terms of excess parameters rather than actual values. Non-ideal liquid mixtures show considerable deviation from linearity in their concentrations and this can be interpreted as the presence of strong or weak interactions. The extent of deviation depends upon the nature of the constituents and composition of the mixtures. The thermodynamic excess properties are found to be more sensitive towards intermolecular interaction among the component molecules of liquid mixtures. The sign and extent of deviation of excess parameters depend upon on the strength of interaction between unlike molecules [39]. So various excess acoustic and thermodynamic parameters have been evaluated and corresponding graphs are also given.
The sign and magnitude of excess ultrasonic velocity (\({u}^{E}\)) play an important role in describing molecular rearrangement as a result of the molecular interaction between the component molecules in the mixtures. The excess ultrasonic velocity (\({u}^{E}\)) curves at 303.15 K varying with mole fraction of 1,4-dioxane are represented in Figure-1 for the six binary systems. The excess ultrasonic velocity values exhibiting positive in all six binary systems. Generally, the value of the excess function (\({u}^{E}\)) depend upon several physical and chemical contributions [40–41]. The physical contribution depends mainly on two factors, namely:
1. The Dispersion Forces Or Weak Dipole-dipole Interaction That Leads To Positive Values.
2. The geometrical effect allowing the fitting of molecules of two different sizes in to each other’s structure resulting in negative values
The chemical contributions include breaking up of the associates present in pure liquids, resulting in positive \({u}^{E}\). In the present mixture the graphical representation of excess sound velocity (\({u}^{E}\)) are positive, presented in Fig. 1. The positive values reveal that there are present weak interactions in the mixture.
The observed positive trends in excess sound velocity indicate that the effect due to the breaking up of self-associated structure of the components of the mixtures is dominant over the effect of hydrogen bonding and dipole dipole interaction between unlike molecule. The excess sound velocity values in the sequence 1-methanol < 1-ethanol < 1-propanol < 1-butanol < 1-hexanol < 1-octanol which also reflects the decreasing strength of interaction unlike molecule in the mixture.
The measurement of viscosity in binary liquid mixture gives some reliable information in the study of intermolecular interaction. The molecules of one or more components forming the temarise are either polar, associating or accordingly show non-ideal behavior’s in mixtures. Negative values of \({\eta }^{E}\) in most of the cases are the consequence of lower viscosity contributions of similar non-specific interaction and hydrogen bonding effect of molecular species in real mixtures rather than those in the corresponding ideal mixtures. In the present study, it is observed that, for the six binary systems the \({\eta }^{E}\) values gradually decrease up to the mole fraction around 0.5 and then begins to increase Fig. 2 more over it is observed that the \({\eta }^{E}\)values decrease as the concentration of \({x}_{1}\)increase. The negative values imply the presence of dispersion forces between the mixing components in the mixtures.
The excess free volume (\({V}_{f}^{E}\)) is another important parameter through which molecular interactions can be explained. In the present investigation the negative excess free volume (\({V}_{f}^{E}\)) for binary mixtures of 1,4-dioxane with alkanols may be attributed to hydrogen bond formation through dipole-dipole interaction between alkanol and 1,4-dioxane molecule or to structural contributions arising from the geometrical fitting of one component (alkanol) into the other (1,4-dioxane) due to difference in the free volume between components.
In order to substantiate the presence of interaction between the molecules, it is essential to study the excess parameter such as free volume. The deviation of physical property of the liquid mixtures from the ideal behavior is a measure of the interaction between the molecules which is attributed to either adhesive or cohesive forces [42]. In the present study, alkanols in a polar and has self - association character in other polar organic solvents.
The negative values of excess free volume (\({V}_{f}^{E}\)) indicate the presence of strong molecular interaction [43–44]. We may conclude that alkanols, which is a self – associating polar organic liquid has a tendency to form complexes with 1,4-dioxane and the increase in its dilution causes disruption of aromatic C – H bond stretching as the self – association of alkanols is disrupted. It is also concluded that suryanarayana approach for estimating free volume of binary liquid mixtures, based on dimensional analysis using thermodynamic consideration is very well applicable in the present case.
The excess internal pressure (\({p}_{i}^{E}\)) is another important parameter through which molecular interactions can be explained. In the present investigation for the six binary systems it is observed that, as the mole fraction of 1,4-dioxane increase, the \({p}_{i}^{E}\)values decreases. The values of 𝑝𝑖 are almost negative and gradually decrease and move towards the positive values by the increase of mole fraction of 1,4-dioxane. More over the 𝑝𝑖 𝐸 decrease with increase in 𝑋1. This situation is observed for all six binary system under study and can be viewed from plots Fig. 6.
This suggests that dipole and dispersion force are operative in these systems, when the 1,4-dioxane concentration low. When the concentration of 1,4-dioxane leads to specific interactions, i.e. the interactions move from weak to strong which supports the above arguments is case of other parameters