Embed Size (px)
Citation preview
Introduction
Page 1
1.0. Introduction
Ultrasound is the part of spectrum which ranges from about 20 KHz to 10 MHz which
can be roughly sub-divided in three main regions; low frequency- high power
ultrasound (20-100 KHz), high frequency-medium power ultrasound (100 KHz – 1
MHz) and high frequency-low power ultrasound (1-10 MHz). The range from 20 KHz
to about 1 MHz is used in sonochemistry whereas frequencies far above 1MHz are
used as medical and diagnostic ultrasound.
Figure 1.1: Spectrum of ultrasonic
They are distinct from electromagnetic waves in the way that they need a medium to
propagate. Like any other wave, an ultrasound wave is defined by its frequency,
velocity and amplitude or intensity. Acoustic waves can be classified as longitudinal
waves, shear waves and surface or Rayleigh waves. The particles in the longitudinal
Introduction
Page 2
waves move in the direction of displacement, whereas in shear waves the movement
is perpendicular to the movement of wave. The waves which travel very close to the
surface are called surface or Rayleigh waves.
Sonochemistry is the application of ultrasound to the chemical reactions and
processes. Acoustics is the science of sound which deals with the production of sound
from the source to the receiver, the detection and perception of sound. Acoustics has
become a broad interdisciplinary field, covering the areas of physics, chemistry, bio-
chemistry, engineering, speech, audiology, music, architecture, neuroscience and so
on. In fact, one of the oldest branches of physics, i.e., acoustic initially originated with
Pythagoras’s study of music over approximately three thousand years ago. The word
acoustics is derived from the Greek Word “AKOUEIN” which means “to hear”. The
first person to use the term acoustic to the science of sound was Sauveur1.
In the present usage, the term sound implies not only phenomenon in air responsible
for the sensation of hearing but also whatever else is governed by analogous physical
principles. Thus, disturbances with frequencies too high (ultrasound) or too low
(infrasound) to be heard by a normal person are also regarded as sound. Ultrasound is
important not only in medical science but is also useful in industrial imaging. It finds
applications in scientific researches especially in the study of solids and liquids2.
Natural phenomena are generators of infrasound. The sudden shock waves of an
explosion propel complex infrasonic signals far beyond the shattered perimeter. The
earthquakes also generate intense infrasonic waves. The faster moving primary waves
arrive at distant locations much before the destructive secondary waves. The primary
waves carry the information whereas the secondary waves carry energy. Certain
animals and fish have the capacity to sense these infrasonic waves and thus have
natural tendency to react with fear and anxiety.
Sound is considered to be older than light because the astronomical evidences suggest
that sound waves was a plasma of charged particles and opaque to electromagnetic
radiations and these waves propagated in the universe at a very low frequency in the
initial years of the existence of universe. Sound can be produced by a number of
different processes, for example, vibrating bodies, changing airflow, time dependent
heat sources, supersonic flow, etc. Unlike electromagnetic radiations, which can travel
Introduction
Page 3
in the vacuum, the sound waves require a medium (for example: solid, liquid or gas)
to travel. Another important difference is that the sound travels much slower than
electromagnetic radiations. The speed of sound in air at sea level is approximately 300
m/sec which is roughly one millionth the speed of light in air.
1.1. Speed of sound in air
From earliest times, there was agreement that sound is propagated from one place to
another by some activity of the air. The Jesuit priest Athanasius Kircher was one of
the first to observe the sound in a vacuum chamber and since he could hear the bell he
concluded that air was not necessary for the propagation of sound. Robert Boyle,
however, repeated the experiment with a much improved pump and noted the much
observed decrease in sound intensity as the air is pumped out. We now know that
sound propagates quite well in rarified air, and that the decrease in intensity at low
pressure is mainly due to the impedance mismatch between the source and the
medium as well as the impedance mismatch at the walls of the container. As early as
1635, Gassendi measured the speed of sound using firearms, assuming that the light
of the flash is transmitted instantaneously. His value came out to be 478 m/s. In a
more careful experiment, Lenihan et al3. determined the speed of sound to be 450 m/s.
In 1650, G.A.Borelli and V. Viviani of the Accademia del Cimento of Florence
obtained a value of 350 m/s for the speed of sound4. Another Italian G.L. Bianconi,
showed that the speed of sound in air increases with temperature5. The first attempt to
the speed of sound in air was apparently made by Sir Isaac Newton. He assumed that
when a pulse is propagated through a fluid, the particles of fluid move in simple
harmonic motion and that if this is true for one particle, it must be true for all adjacent
ones. The result is that the speed of sound is equal to the square root of the ratio of the
atmospheric pressure to the density of the air. This leads to values that are
considerably less than those measured by Newton and others.
In 1816, Pierre Simon Laplace suggested that in Newton and Lagrange’s calculations
an error had been made in using for the volume elasticity of the air pressure itself,
which is equivalent to assuming the elastic motions of the air particles taking place at
constant temperature. In view of the rapidity of the motions, it seemed more
reasonable to assume that the compressions and rarefactions follow the adiabatic law.
Introduction
Page 4
The adiabatic elasticity is greater than the isothermal elasticity by a factor γ (gamma)
which is the ratio of the specific heat at constant pressure to that at constant volume.
The speed of sound should, thus, be given by c = (γ p/ρ) 1/2
, where p is the pressure
and ρ is the density. This gives much better agreement with experimental values6.
1.2. Speed of sound in liquids and solids
The first serious attempt to measure the speed of sound in liquid was probably that of
the Swiss physicist Daniel Colladon, who in 1826 conducted studies in Lake Geneva.
Colladon measured the static compressibility of several liquids and decided to check
the accuracy of his measurements by measuring the speed of sound which depends on
the compressibility. The compressibility of water computed from the speed of sound
turned out to be very close to the statically measured values7. In 1808, the French
physicist, J. B. Biot measured the speed of sound in 1000 m long iron water pipe in
Paris by direct timing of the sound travel8. He compared the arrival times of the sound
through the metal and through the air and found the speed to be much greater in
metal. Chladni had earlier studied the speed of sound in solids by noting the pitch
emanating from a struck solid bar, just as we do today. He deduced that the speed of
sound in tin is about 7.5 times greater than in air, while in copper it was about 12
times greater. Biot’s values for the speed of sound in metals agreed well with
Chladni’s.
1.3. Speed of sound in liquids
a) Liquid structure and its relation to sound speed
From an acoustical point of view, the liquid is a state intermediate between a gas and
a solid. It is gas like in that, in the absence of losses, it does not offer resistance to a
shear stress and solid like in that its bulk modulus is determined by intermolecular
bonding forces and not by external forces (e.g., gravity) or constraints (enclosure
walls), as in a gas.
This state of affairs is best explained by a modern picture of liquid structure9. The
radial distribution function (molecular number density v/s radial distance) obtained
from x-ray and neutron diffraction patterns clearly shows regions of highly ordered
structure as found in a crystalline solid. These regions, called aggregates or sometimes
Introduction
Page 5
clusters, are of limited spatial extent, ranging from a few molecular diameters to
macroscopic dimensions. Liquids showing little tendency toward aggregation are
called unassociated; those containing a substantial distribution of small-sized
aggregates are called associated and those containing long chains of aggregates are
called polymerized. The prevailing amorphous matter contains an abundance of micro
cavities, called holes, of varying size and distribution which are responsible for the
fluidity of the liquid. The major impact of the holes is an enhancement of the free
volume, which plays a key role in the emergence of many equilibrium and transport
properties of the liquid.
The derivation of the sound speed of a liquid from its microscopic properties requires
realistic expressions for the equation of state and the internal energy, leading in turn
to the bulk modulus and specific heat. Successful theoretical developments in these
areas have been limited. Among the difficulties are the incorporation of the free
volume into the equation of state and the tabulation of contributions to the free
energy, which is not as straight forward as in a gas. The most successful efforts are,
for the most part, at least partially empirical.
b) The equation of state
The general form of an equation of state
,...,TfP …. (1.1)
yields a bulk modulus
T
fPM
s
…. (1.2)
As a gas condenses to a liquid, the second term becomes decisive owing to the large
increase in density.
The development of a successful equation of state of a liquid must address the issues
of molecular bonding, association and polymerization, and free volume in both the
ordered and disordered structure. The principal approaches are as follows:
Introduction
Page 6
1. Semirigorous derivations based on a liquid model: These include the celebrated
Lennard Jones and Devonshire cell model, the Eyring hole model and correlation
models to determine the radial distribution function. Although these models have
had some success in predicting many physical properties of liquids, they have
been less successful in predicting sound speed.
2. Semi empirical modifications to existing equations of state: A noteworthy
example is the theory of Schaaffs10
, who modified van der Waals equation to
include an improved expression for molecular volume as well as the specifics of
bonds between various types of atoms or molecular complexes. Schaaffs’s
treatment has enjoyed remarkable success in predicting the sound speeds of
unassociated organic liquids.
3. Empirical expressions fitted to experimental data: A common procedure is to
expand one state variable in a series (not necessarily a power series) of the others.
In applications to sound speed, however, the specific heat at one reference point
remains an unknown parameter. Therefore, it is useful to expand the sound speed
itself in terms of state variables, an approach taken by Itterbeek and Dael11
for
cryogenic liquids.
c) Speed of sound in unassociated liquid: Schaaffs’s method
Schaaffs’s formulas10
to compute the sound speed are
BM
BCC R
.… (1.3)
i
ii ,MzM .… (1.4a)
B = ∑ zi Bi …. (1.4b)
i
iiz .… (1.4c)
where M is the molecular mass, B the external addendum (molecular volume per
mole), the internal addendum (heavy atom corrective volume), zi the number and
Mi the mass of the ith species, CR = 4450 m/s, and Bi and i contribution from the ith
species.
Introduction
Page 7
d) Speed of sound in associated liquids (water)
A successful treatment of many physical properties of an associated liquid must
account for the role of structural complexes. For illustration, one of the models of
water12
- considered an exemplary associated liquid - assumes the liquid composition
to be a mix of the open tridymite (ice like) structure and more closely packed quartz
like structure. Another model12
assumes the structure to contain a distribution of
polymeric units, namely, the monomer, dimer, tetramer and octamer, the last of which
has the open tridymite structure. As the temperature increases toward the boiling
point, the closely packed constituents gain at the expense of the vanishing tridymite.
The competition between structural redistribution and thermal expansion explains
such exceptional properties of water as the density maximum at 4 0C and the sound
speed maximum at 74 0C.
A precise expression for the sound speed in saturated water versus temperature,
promising an error not to exceed 0.05%, is given by Chavez etal.13
.
5
01
k
k
k
a
c
TbT
Tc …. (1.5)
where Tc, a and the coefficients are given in Table 1.1. Equation (1.5) yields c =
1481.8 m/s. An increase in pressure increases the sound speed14
.
1.4. Different branches of acoustics
Various branches of acoustics that deal with different aspects of sound and hearing
include the following:
Physical acoustics
Musical acoustics
Underwater acoustics
Engineering acoustics
Architectural acoustics
Speech communication
Introduction
Page 8
Structural acoustics and vibration
Physiological and psychological acoustics.
Table 1.1: Parameters entering Chavez, Sosa, and Tsumura’s formula (Eq. 1.5)
for temperature dependence of sound speed in pure water
K bk
0 -19214.88484
1 230.1609318
2 -1.028803876
3 0.002414336487
4 -2.902395566 x10-6
5 1.4304933449 x 10-9
A 0.75
Tc (k) 647.067
Physical acoustics
Although all of acoustics, the science of sound, incorporates the laws of physics, we
usually think of physical acoustics as being concerned with fundamental acoustic
wave propagation phenomena, including transmission, reflection, refraction,
interference, diffraction, scattering, absorption, dispersion of sound and the use of
acoustics to study physical properties of matter and to produce changes in these
properties. The foundation for physical acoustics was laid by such 19th
century giants
as Helmholtz, Rayleigh, Tyndall, Stokes, Kirchhoff and others.
Introduction
Page 9
As acousticians had extended their studies to frequencies above and below the audible
range, it is conventional to identify these frequency ranges as “ultrasonic” and
“infrasonic” respectively, while letting the word “acoustic” refer to the entire
frequency range without limit.
Human ear is sensitive to sounds of frequency lying between 20 Hz and 20,000 Hz.
The ear is unable to hear sounds of frequency less than 20 Hz and more than 20,000
Hz. The sounds of frequency less than 20 Hz are called “infrasonic”, while those of
frequency more than 20,000 Hz are called “ultrasonic”. In other words, ultrasonic is
longitudinal mechanical waves of frequency beyond the highest audible frequency
(i.e., 20,000 Hz).
In the past, ultrasonic technique has been used in the study of solute-solute and solute-
solvent interactions for amino acids, sugars, polyols, etc. in aqueous as well as in
mixed aqueous solution. Because of the complex nature of these molecules, it is very
difficult to understand the nature of interactions they have in aqueous solutions. It is
the structure of water which governs the properties of solute in aqueous solutions.
Therefore, it becomes necessary to give a brief review of structure of water and
aqueous solutions to study such interactions and various thermodynamic properties
associated with it.
1.5. Water: Structure and properties
Water is a unique, ubiquitous substance which is a major component of all living
things. Its nature and properties have intrigued philosophers, naturalists and scientists
since antiquity. Water continues to engage the attention of scientists today as it
remains incompletely understood in spite of intense study over many years. This is
primarily because water is anomalous in many of its physical and chemical properties.
Some of water’s unique properties are literally essential for life, while others have
profound effects on the size and shape of living organisms, how they work and the
physical limits or constraints within which they must operate. The structure and
properties of water at the molecular level has been studied through spectroscopic and
thermodynamic experiments. The more recent discipline of computer simulation has
also played a role, having achieved a level of sophistication in the study of water in
Introduction
Page 10
which it can be used to interpret experiments and simulate properties not directly
accessible by experiment.
1.6. Basic physical properties
Selected physical properties of water are given in Table 1.2. To put these in context,
comparison is made with the organic solvents methanol and dimethyl ether, where
one and two of the hydrogen atoms are replaced by a methyl group, respectively.
Water is a small solvent, occupying about 0.003 nm3 per molecule in the liquid state
at room temperature and pressure, yet it is highly cohesive because of the strong
intermolecular interactions (hydrogen bonds or H-bonds) between the oxygen and
hydrogen atoms. This is reflected in its high boiling point, the large amount of heat
needed to vaporize it and its high surface tension. Replacement of one or both of the
hydrogen dramatically weakens these intermolecular interactions, reducing the
magnitude of these quantities. The strong cohesive interactions in water also result in:
(1) A high viscosity, since for a liquid to flow interactions between neighboring
molecules must constantly be broken; and
(2) A high specific heat capacity – the ability to store a large amount of potential
energy for a given increment in kinetic energy (temperature).
Table 1.2: Selected physical properties of water, methanol and dimethyl ether at
298 K
Property Water Methanol Dimethyl ether
Formula H2O CH3OH (CH3)2O
Molecular weight (g mol–1
) 18 32 46
Density (kg L–1
) 0.998 0.7914 0.713
Boiling point (K) 373 338 248
Volume of fusion (nm3) 0.0027 Negative Negative
Introduction
Page 11
Liquid density maximum (K) 277 None None
Specific heat (JK–1
g–1
) 4.18 2.53 2.37
Specific heat (JK–1
mol–1
) 75.2 81.0 109.0
Heat of vaporization (kJ g–1
) 2.3 1.16 0.40
Heat of vaporization (kJ mol–1
) 41.4 37.1 18.4
Surface tension (mN m–1
) 72.8 22.6 16.4
Viscosity (μPa s) 1002 550 233
Dielectric constant 78.6 33.6 5.0
Dipole moment (Cm×1030
)a, a=(gas)
6.01 5.68 4.34
In part water’s high specific heat and heat of vaporization relative to other liquids
results from its small size. More intermolecular interactions are contained in a given
volume of water than comparable liquids. When this is taken into account by
expressing the specific heat and heat of vaporization on a molar basis, methanol and
water are comparable. The surface tension of water, however, is still anomalously
large after accounting for differences in size. Water has one of the highest dielectric
constants of any non-metallic liquid. It also has the remarkable properties of
expanding when it is cooled from 4 0C to its freezing point and again when it freezes.
Both the expansion of water and its high dielectric constant reflect subtle structural
features of liquid water at the molecular level.
1.7. Biological relevance of water’s physical properties
Water, owing to its high boiling point, exists predominantly in its liquid form in the
range of environments where life flourishes, although the other two phases, ice and
vapor, play an essential role in shaping the environment. The high specific heat and
heat of vaporization of water have important consequences for organisms at the
Introduction
Page 12
cellular and physiological level, in particular, for the efficiency of processes involving
heat transfer, temperature regulation, cooling, etc. Viscosity is the major parameter of
water that determines how fast molecules and ions can be transported and how rapidly
they diffuse in aqueous solution. It, thus, provides a physical upper limit to the rates
of many molecular level events within which organisms must live and evolve. These
include the rates of ion channel conductance, association of substrates with enzymes,
binding rates and rates of macromolecular assembly. It also sets an upper bound to the
length scale over which biological processes can occur purely by diffusion. In many
cases, for example, in enzyme–substrate reactions, evolution has pushed the
components of living systems to the limits set by water’s viscosity.
The high surface tension of water is relevant at two levels. First, below a length scale
of about 1 mm surface tension forces dominate gravitational and viscous forces, and
the air – water interface becomes an effectively impenetrable barrier. This becomes a
major factor in the environment and life style of small insects, bacteria and other
microorganisms. Second, at the molecular (0.1–100 nm) scale, the surface tension
plays a key role in water’s solvent properties. The high dielectric constant of water
also plays an important role in its action as a solvent. The biological significance of
the expansion of water upon cooling below 4 0C and upon freezing, though crucial, is
largely indirect through geophysical aspects such as ocean and lake freezing, the
formation of the polar ice cap and in weathering by freeze–thaw cycles.
1.8. Hydrogen bonding
Water exists in three phases: vapor, liquid and ice, the last of which has at least nine
known forms. For biological phenomena, the most important is the liquid phase. It is
useful, however, when describing its structure of which the simplest form of ice, Ice I,
is used as a reference. The structures of both are dominated by the hydrogen-bonding
interaction. The hydrogen bond (H-bond) is a strong bond formed between a polar
hydrogen and another heavy atom, usually, carbon, nitrogen, oxygen or sulfur in
biological molecules. In the gas phase, the strength of H-bond between two waters is
22.7 kJmol-1
, although in liquids and solids its strength is greatly dependent on
geometry and the surrounding molecules. It is, sometimes, characterized as
intermediate between ionic and covalent bonds in character, although its energy as a
Introduction
Page 13
function of the length and angle can be quite accurately described by coulomb
interaction between the partial atomic charges on the hydrogen, the heavy atom it is
covalently attached to and the oxygen, nitrogen, carbon or sulfur atoms with which it
is making the H-bond.
1.9. Different models for structure of water
Water is unique among liquids due to its anomalous physico-chemical properties
usually not found in other liquids, for example, contraction upon melting (as in
Germanium and Bismuth), density maximum, negative pressure coefficient of
viscosity, high melting and boiling points, high latent heats of fusion and evaporation,
high dielectric constant and high molar heat capacity. In spite of extensive efforts and
investigations carried out to understand the structure of water not a single completely
satisfactory self-consistent model capable of explaining all these anomalous
properties has been proposed.
The structural research on water originated in a classical paper by Bernal and
Fowler15
. They showed that liquid water is best described as a rather broken down and
slightly expanded (mean o-o distance: ice 276 pm, liquid water 292 pm) form of the
ice lattice. Thus X-ray and other techniques indicate that in water there is a
considerable degree of short range order which is characteristic of tetrahedral bonding
in ice.
Thus, liquid water partly retains the tetrahedral bonding resulting in network structure
characteristic of crystalline ice. In addition to the water molecules that are part of the
network, some structurally free, non associated water molecules can be present in the
interstitial region of the network (Fig. 1.2). When a network water molecule breaks its
hydrogen bonds with the network, it can move as an interstitial water molecule that
can rotate freely. The classification of water molecules into network water and free
(or interstitial) water is not static but dynamic one
Introduction
Page 14
Figure 1.2: Schematic diagram to show that in liquid water there are networks of
associated water molecules and also a certain fraction of free, unassociated water
molecules
.
Introduction
Page 15
Figure 1.3: Schematic representation of the crystal structure of ice-I at low pressure
In a classical paper by Frank andWen16
, it was argued that clusters of water molecules
co-operate to form networks and at the same time the networks break down. A water
molecule may be free in an interstitial position at one instant and in the next instant it
may become as a unit of the network. Later, the tetrahedral model was also supported
by Morgan and Warren17
which is similar to that in ice-I (Fig. 1.3). Taking this as a
starting point, various models have been suggested to explain water structure which
can be grouped into two general categories: “continuum” model and “mixture” model.
Continuum model
Using continuum model, one describes liquid water as still essentially complete
hydrogen bonded network with a distribution of hydrogen bond energies and
geometries18-21
. This model considers the average strength of hydrogen bonds in water
to be weaker than in ice as a result of irregular distortion and elongation both of which
Introduction
Page 16
increase with temperature. This model fails to explain the entropy data and, therefore,
also hydration properties of non-polar molecules.
Mixture model
Using mixture model, one describes liquid water as an equilibrium mixture of
molecular species with different number of hydrogen bonds per molecule22-26
. Such a
description implies the disruption of a well defined proportion of hydrogen bonds at
any temperature. Depending on the nature of species involved, a number of models
have been reported to explain structure of water.
1. Interstitial model
2. Water hydrate model
3. Flickering cluster model
Out of these three models, flickering cluster model is most important in the area of
solution chemistry, which is described briefly below.
Flickering cluster model
This model was proposed by Frank and Wen16
. They considered water as a mixture of
cluster of hydrogen bonded water molecules (bulky water) and monomers (denser
water) in equilibrium with each other. The phenomenon of formation of hydrogen
bonds in liquids is a co-operative phenomenon, i.e., the bonds are not made and
broken singly but several at a time, thus, producing short lived clusters of highly
hydrogen bonded regions surrounded by non-hydrogen bonded molecules. The
formation and dissolution of these flickering clusters of water molecules of short life
time (10-11
s to 10-10
s) is governed by local energy fluctuations. This model can
account qualitatively for various experimentally observed quantities such as density
data, relaxation times in various processes, the structural changes in solutions of non-
polar substances and the subsequent changes in thermodynamic parameters.
1.10. Review of literature
A literature survey shows that ultrasonic studies have been carried out in a variety of
binary liquid mixtures. It reveals the fact that ultrasonic has been a subject of active
interest during the recent past. Recent literature on ultrasonic studies show that
Introduction
Page 17
ultrasonic still exists as a potential tool in evaluating intermolecular interactions,
energy exchange between various degrees of freedom and non-linear properties in
binary liquid mixtures.
1.10.1. Intermolecular interactions in binary liquid mixtures
Ultrasonic velocity and intermolecular interactions existing in binary liquid mixtures
are clearly explained using excess thermodynamic functions derived from ultrasonic
velocity and density measurements. Rajaguru and Jeyaraj27
studied the excess
thermodynamic functions of binary mixtures of allyl alcohol with 1,4 dioxane and
carbon tetrachloride at two different temperatures and concluded that heteromolecular
interactions exist in the allyl alcohol + 1,4 dioxane system and dispersion forces exist
in allyl alcohol + carbon tetrachloride system. Reddy et al.28
studied the volumetric
and ultrasonic behavior of ethyl acetate with some chloroethanes and chloroethenes.
The experimental data was used to explain the effect of successive chlorination and
unsaturation of ethane molecule. Belsare et al.29
determined specific acoustic
impedance and adiabatic compressibilities in binary mixtures of o-chlorophenol, p-
chlorophenol, chlorobenzene and nitrobenzene with benzene. They suggested that
only a weak interaction such as dispersion forces should be active in these mixtures.
Govindappa et al.30
measured sound velocities in binary mixtures of 1-chlorobutane
with benzene, toluene, o-xylene, m-xylene, p-xylene, chlorobenzene, bromobenzene
and nitrobenzene. From the sound velocity and density data, excess compressibilities
were derived and it was concluded that weak dipole- induced dipole interactions and
dipole-dipole interactions were present in these systems. Rao et al.31
estimated several
excess functions like excess enthalpy, excess viscosity and excess Gibb's free energy
from ultrasonic velocity and viscosity determinations in binary liquid mixtures of
toluene with different alcohols. They observed that as the concentration of toluene
was increased, there was a possibility of breaking of the hydrogen bonds, which
associates the alcohol molecule. Srinivasulu and Naidu32
evaluated the
compressibility and excess compressibility from ultrasonic velocity and density
measurements in binary mixtures of l, l, l-trichloroethane with different alcohols and
observed that excess compressibilities were positive in all these binary systems which
Introduction
Page 18
indicated that weak interactions, due to the structure breaking effects of 1, l, l-
trichloroethane, were present. Chennarayappa et al.33
determined the excess
compressibility values in binary mixtures of methyl cyclohexylamine with several
alcohols. From the magnitude and sign of the excess compressibilities they found that
strong hydrogen bond interactions exist in these systems. Singh and Kalsh34
studied
various thermo acoustical parameters and excess thermodynamically functions in
binary mixtures of tetrabutyltin chloride, tributyltin chloride and dibutyltin dichloride
with tetrahydrofuran. They concluded that complex formations are absent in these
liquid mixtures and molecules interact weakly through dispersion forces. Dewan et
al.35
determined the experimental values of ultrasonic velocities in binary mixtures of
ethylbenzene with acetonitrile, butyronitrile, nitromethene and nitroethane at 303.15
K. The experimental velocities were compared with the theoretical values calculated
by Flory, Jacobson and Schaaffs theories. They observed that the velocity values
computed using Schaaff's theory10
agreed well with the experimental values of
ultrasonic velocity in these binary mixtures. Rajendran and Benny36
measured the
ultrasonic velocity in the binary mixtures of triethylamine with different alcohols and
evaluated the compressibility and its excess value. From the magnitude and sign of
excess compressibility values they suggested that strong hydrogen bond interactions
between NH2 group of triethylamine and OH group of alcohols were present in these
binary systems. Ramanjappa et al.37
evaluated excess sound velocity and excess
specific acoustic impedance in binary mixtures of di-n-propylether + n - heptane, 3, 6-
dioxaoctane + n-heptane and 2, 5, 8-trioxanonane + n-heptane. In these studies, they
concluded that due to inductive effect several oxygen atoms weakens the C-H bonds
and enhance the hydrogen bonding and this leads to self association of molecules. Rao
et al.38
studied ultrasonic speed and isentropic compressibilities of binary mixtures of
acetonitrile with some amines of n-butylamine, sec-butylamine, tert-butylamine, n-
pentylamine, n-hexylamine, n-heptylamine, n-octylamine, and cyclohexylamine at
303.15 K. In such studies, the excess isentropic compressibility was found to be
negative for the binary mixtures of n-butylamine, sec-butylamine and tert-butalamine
with acetonitrile while positive excess compressibilities were found in the mixtures of
hexylamine, octylamine, pentylamine and heptylamine with acetronitrile. From these
Introduction
Page 19
observations, they suggested that positive excess compressibility is an indication of
weak interaction (due to loss of dipolar association), which contributes to increase in
the interspace between molecules in the mixture and negative excess compressibility
is an indication of strong interaction between electrostatic forces of dipoles.
Padmasree and Prasad39
studied ultrasonic behavior in binary mixture of ethylacetate
+ n-butanol at 303.15 K, 313.15 K and 323.15 K. Jacobson and Schaaff”s theories
were successfully applied to these binary mixtures. From the characteristics of excess
functions, they found that interactions between unlike molecules are predominant in
the binary mixtures besides interstitial occupation which dominates other types of
interactions. Reddy et al.40
evaluated the excess thermodynamic functions of three
binary mixtures of acetophenone, 4-chloro acetophenone and 2-hydroxy
acetophenone with isopropanol as the common component by measuring ultrasonic
velocity, density and viscosity. They observed that there was no complex formation
but a strong molecular interaction was present in those binary systems which were
due to the interstitial accommodation of acetophenone molecule in the H-bonded
alcohol structures and orientational ordering leading to more compact structures. Siva
Prasad and Venkateswarlu41
determined ultrasonic velocity in the binary mixtures of
2-butoxyethanol with benzene, toluene, o-xylene, m-xylene, p-xylene, chlorobenzene,
bromobenzene and nitrobenzene at 303.15 K. The excess compressibility curve
showed a positive deviation for the binary mixture of 2-butoxyethanol with three
xylenes and a negative deviation for other mixtures. The positive deviation of excess
compressibility revealed that structural effects predominated over the effects of
complex formation between ᴨ electrons of benzene ring and oxygen in 2-
butoxyethanol and the negative deviation was attributed to the decrease in free length
due to complex formation through charge transfer and dipolar association between the
component molecules. Pandey et al.42
measured sound velocity and density in six
binary mixtures namely n-heptane + toluene, n-heptane + n-hexane, toluene + n-
hexane, cyclohexane + n-heptane, cyclohexane + n-hexane and n-decane + n-hexane
at 298.15 K. The calculated isothermal compressibility was compared with the
theoretically calculated values using hard sphere equation of state and Flory's
statistical theory and a satisfactory agreement was found. Kalra et al.43
studied the
Introduction
Page 20
molecular interactions in mixtures of quinoline with some aromatic hydrocarbons
using ultrasonic, dielectric and viscometric methods. From the study, they concluded
that strong specific interactions resulting from H-bond formation, closer molecular
arrangement, donor acceptor interaction and self association of quinoline exists
between unlike molecules. Chauhan et al.44
studied ultrasonic velocity and viscosity
in a binary mixture of acetonitrile with propylene carbonate. The excess
compressibility was evaluated and the negative nature of excess compressibility
revealed that strong dipole-dipole interaction existed in the binary mixture. Rout and
Chakravortty45
studied the molecular interaction existing in binary mixtures of
acetylacetone with isoamyl alcohol, benzene and carbon tetrachloride at four
temperatures. The excess thermodynamically functions were evaluated from
ultrasonic velocity, viscosity and density measurements. The nature and sign of
excess functions indicated that strong dipole-induced dipole interactions were present
in acetylacetone + carbon tetrachloride mixture while the interactions present in the
other two systems were weak. Rajendran and Marikani46
measured ultrasonic
velocities in liquid mixtures of aniline with methanol, ethanol and phenol at 303.15 K.
From nature of excess compressibility and excess internal pressure, they found that
hydrogen bond interaction was present in aniline-methanol and aniline-ethanol binary
systems while a 2: 1 complex formation was predominant in aniline-phenol mixture.
Lafuente et al.47
studied the excess compressibilities of binary mixtures of several
isomers of chlorobutane with isomers of butanol. From these observations they found
that negative excess compressibility values might be due to better packing of the
molecules in the mixture that could lead to a smaller compressibility than that of the
ideal mixture. Chauhan et al.48
calculated several acoustical parameters in the binary
mixture of acetonitrile + propylene carbonate by measuring ultrasonic velocity and
density. The nature and behavior of acoustical parameter like Rao's constant, Wada's
constant, etc. revealed the absence of any complex formation and the presence dipole-
dipole interactions in this system. Nikam et al.49
studied the acoustical properties of
nitrobenzene with several alcohols at 303.15 K. The excess functions like excess
compressibility and excess intermolecular free length were found to be negative in all
these systems, which showed the presence of strong dipole-dipole type molecular
Introduction
Page 21
interactions between nitrobenzene and alcohols. Chauhan et al.50
measured ultrasonic
velocity, density and viscosities in the binary mixtures of methanol with dimethyl
sulphoxide and dimethyl formamide, and dimethyl sulphoxide with dimethyl
formarnide at 298 K, 308 K and 318 K. The excess functions revealed that hydrogen
bond interactions were present in methanol + dimethyl sulphoxide and methanol +
dimethyl formamide systems where as both dipolar and hydrogen bonding
interactions were present in dimethyl sulphoxide + dimethyl formamide systems.
Gupta and Shukla51
studied molecular association in binary mixtures of dioxane with
formic acid, salicylic acid and benzoic acid using ultrasonic velocity data. The non-
linear variations of velocity, intermolecular free length, specific acoustic impedance
and Rao's constant supported the existence of complex formation in these binary
systems. Rajendran52
carried out volumetric, viscometric and ultrasonic behaviour of
binary mixtures of n-heptane with some isomeric alcohols at 298.15 K. In these
measurements they found that the strength of intermolecular interactions decreased
with increase in size of alcohol molecules and complex formation was absent in these
systems.
1.10.2. Intermolecular interactions in solutions of amino acids
In the last chapter (Chapter –VII), work has also been reported on solution containing
amino acids. The survey of literature in this field suggests that vast amount of work
has been done on aqueous and mixed aqueous amino acid solutions. Many
researchers53-55
investigated the solubility of amino acids in terms of activity and
osmotic coefficients in water. Solubility of amino acids as a function of temperature
and pH was reported by Amend and Helgeson56
.
The determination of the factors governing the conformational stability of
biopolymers is of fundamental importance for many biological phenomena. Solute-
solvent and solute-solute interactions are of primary importance in the maintenance of
native conformation of proteins and nucleic acids. Thermodynamic and transport
properties such as partial molar/molal volume, heat capacity, free energy, enthalpy,
compressibility, viscosity, surface tension, etc. have been shown to yield valuable
information regarding the relative magnitude of various solute-solvent and solute-
solute interactions.
Introduction
Page 22
Millero et al.57
determined the apparent molal volume and adiabatic compressibility of
several amino acids in water and calculated the number of water molecules bonded to
the charged centers of α-amino acids. The number of hydrated water molecules,
electrostriction partial molal volume and compressibility were also determined from
partial molal volume and compressibility data. They have also estimated various
group contributions for the partial molal volume and compressibility by different
methods for the studied amino acids.
Cabani et al.58-60
reported the volumes, compressibilities, expansibilities and heat
capacities of α-amino acids, ω-amino acids and polypeptides in the temperature range
of 298.15 – 328.15 K. The volume change in the formation of zwitterionic structures
are estimated and correlated with distance between the NH3+ and COO
- groups and
with the nature of the chain separating them. It was also shown that partial molar
volumes of amino acids were less than those of neutral molecules and approaches
those of ionic species of similar size. Similar studies on α, ω amino acids were also
carried out by Shahidi and Farrell61
.
Kharakoz62
reported the apparent volume of fourteen amino acids in aqueous solutions
within the temperature range of 288 - 328 K. The decrease in volume of polar and
charged atomic groups as well as the temperature dependences of the partial volumes
was analyzed. The differences in behavior between charged, polar and nonpolar
atomic groups were determined. The surface area of the molecule, in addition to the
van der Waals volume, was considered as an essential parameter in comparing polar
and nonpolar molecules.
Kharakoz63
also measured apparent adiabatic compressibilities of twenty one amino
acids over a wide temperature range. Partial compressibilities of atomic groups have
been determined as function of temperature and interpreted in terms of hydration and
intramolecular interactions between different parts of a molecule.
Jolicoeur and Boileau64
discussed apparent molar volumes and heat capacities of
glycine, alanine, serine and their oligopeptides at 298.15 K. The data was described in
terms of contributions from amino acid side chains –CH3 and –CH2OH and end group
hydration effects. Yayanos65, 66
reported the volumes and compressibilities of aqueous
Introduction
Page 23
amino acids at 298.15 K. The volume change at 1000 atmospheric pressure was also
reported and it was observed that apparent molar volume of dipolar amino acids
increases with pressure. Electrostriction decreases with increasing pressure and
appeared to be dependent on the dipole moment of amino acids.
Partial molar heat capacities and volumes of transfer of some amino acids and
peptides from water to aqueous NaCl and CaCl2 were studied by Bhat and
Ahluwalia67, 68
. The transfer properties were positive because of dominant interactions
of Na+, Ca
2+ and Cl
- with charged centers of amino acids and peptides. The peptide
group is strongly salted in or stabilized by CaCl2 and less so by NaCl. The results
were rationalized by co-sphere overlap model. Positive transfer compressibilities were
also obtained in presence of NaCl and glucose solution by Banipal and Sehgal69
. A
detailed study of apparent molar volumes, compressibilities and refractive indices of
glycine (full concentration range) in aqueous NaCl, KCl, KNO3 and NaNO3 at 298.15
K was also carried out70, 71
. The positive transfer properties obtained indicate glycine
has larger size in aqueous electrolytes than in H2O. This effect was attributed to
doubly charged behavior of glycine and formation of physically bonded ion–pairs
between charged groups of glycine and ions.
Mishra and Ahluwalia72
determined partial molar volumes of zwitterionic α-amino
acids and peptides in aqueous solutions. They have observed deviations from apolar
group additivity up to a distance of four consecutive -CH2 groups remote from the
hydrophilic groups which indicate the long-range of zwitterionic hydration on the
contributions of apolar groups to the volumes.
Taulier and Chalikian73
reviewed the results of compressibility studies on proteins
and low molecular weight compounds that model the hydration properties of these
biopolymers. These analyses were used to define the changes in the hydration
properties and intrinsic packing associated with native to-molten globule, native-to-
partially unfolded and native-to-fully unfolded transitions of globular proteins.
Singh and Banipal74
reported positive partial molar adiabatic compressibility of
transfer at infinite dilution and B-Coefficient of transfer of some amino acids in
aqueous glycerol solutions at 298.15 K. They also calculated activation energy of
Introduction
Page 24
viscous flow in aqueous and mixed aqueous glycerol solutions from B-Coefficient
and partial molar volume data. They also reported hydration number, interaction
coefficients and results had been discussed in terms of solute-cosolute interactions.
Zhao75
has reviewed the viscosity B-coefficients and standard partial molar volumes
of amino acids at various temperatures. He discussed the effect of organic solutes and
various ions on the viscometric and volumetric properties in terms of their
kosmotropic (structure making) and chaotropic effects on the hydration of amino
acids and also interpreted their role on protein stability. In addition to this, he also
reported the volumetric behavior of amino acid ions (cations and anions) because
these ions have been incorporated as a part of novel ionic liquids which have wide
applications in biocatalysts and protein stability.
Pal and Chauhan76
determined partial molar volume, partial molar adiabatic
compressibility, transfer volume, transfer B-coefficients, hydration number and
interaction coefficients of L-alanine in aqueous carbohydrate solution at different
temperatures. These parameters have been discussed in terms of solute-solvent
interactions.
Some data is also available for the thermodynamic properties of amino acids in
presence of aqueous sugars. Uedaira77
reported the activity coefficients of α-
aminobutyric acid and glycylglycine in aqueous sucrose. Bhat et.al.78
measured
densities and heat capacities of some amino acids and peptides in aqueous glucose. It
was found that at low concentration of solute salting in of amino acids takes place,
whereas at higher concentrations salting out of amino acids predominates.
Friedman79
proposed a simple statistical theory called Cluster Integral Expansion
theory for the quantification of interactions between like and unlike charged ions. In
order to derive the theory he used Mayer’s ionic solution theory80
. It has been possible
to compute the excess Gibbs free energy of mixing in terms of contributions made by
pairs, triplets, quadruplets and high order mixing terms. The limiting laws of mixing
of two ions of the same sign have been accurately derived and demonstrated
successfully.
Introduction
Page 25
1.11. Aim of research work
The knowledge of thermo acoustic properties is of great significance in
understanding the physico chemical behavior and molecular arrangement in
various liquid mixtures and solutions. Ultrasonic study of liquids and liquid mixtures is
of considerable importance in understanding intermolecular interactions
between the component molecules and finds applications of such mixtures in
several industrial and technological process81-86
. Speed of sound itself is highly
sensitive to the structure and interactions present in the liquid mixtures as it is
fundamentally related to the binding forces between the constituents of the
medium87
. For the qualitative estimation of the molecular interactions in solutions,
the ultrasonic velocity approach was first studied by Lagemann and Dunbar88
.
The experimental results of ultrasonic speed and density are used to
calculate acoustic and thermodynamic parameters that are found to be very
sensitive with regard to molecular interactions89-99
. The excess properties of the
acoustic and thermodynamic parameters will give the information about the nature and
strength of molecular interactions and are sensitive to the intermolecular forces as
well as to size of the molecules100
. Hence, such measurements are useful to study
the strength of molecular interactions in liquid mixtures.
The thesis is, thus, aimed to seek the following objectives:
(1) To collect a new set of experimental data on various physicochemical properties
such as density, speed of sound and viscosity for the binary liquid systems
containing higher alcohols and the aromatic hydrocarbons as one of the
components at different temperatures and compositions.
(2) To evaluate various thermodynamic functions for the individual properties from
the measured data on pure and mixture components.
(3) To examine the sensitivity of the composition dependence of various
thermodynamic properties to variations in temperature, size, shape and the nature of
the components.
(4) To understand the nature and extent of patterns of intermolecular interactions in
the binary liquid mixtures from the knowledge of the corresponding experimental
Introduction
Page 26
data.
(5) To measure the volumetric properties of amino acids in mixed aqueous solutions
and to study the various parameters like partial molal volume, partial molal
compressibility, etc.
(6) To gather information about interactions in amino acids-water-THF/Methanol.
(7) To study viscous behavior of the binary solutions as well as amino acid solutions
using Jones-Dole equation.
Introduction
Page 27
References
1. R. B. Lindsay, Acoustics: A historical and philosophical development
(Dowden, Hutchinson and Ross, Stroudsburg), Translation of Sauveur’s
paper, p.88, (1973).
2. R. N. Thurston and A. D. Pierce (editors), Physical Acoustics, Vol. XXV
(Academic, San Diego), (1999).
3. L. M. A. Lenihan, Mersenne and Gassendi, Acustica, 2, 96 (1951).
4. D. C. Miller, Anecdotal history of the science of sound (Macmillan, New
York), p.20, (1935).
5. L. M. A. Lenihan, Acustica, 2, 205 (1952).
6. R. B. Lindsay, J. Acoust. Soc. Am., 39, 629 (1966).
7. J. D. Colladon and J. K. F. Sturm, Ann. Chim. Phys., 36, 113 (1827).
8. J. B. Biot, Ann. Chim. Phys., 13, 5 (1808).
9. A. Muenster, “Theory of the liquid state,”in A.Van Itterbeek, Ed., Physics of
high pressures and the condensed phase, (North-Holland, Amsterdam)
(1965).
10. W. Schaaffs, Molekularakustik , (Springer-Verlag, Berlin) (1963).
11. A. Van Itterbeek and W. Van Dael, Physica, 28, 861 (1962).
12. K. F. Herzfeld and T.A. Litovitz, Absorption and dispersion of ultrasonic
Waves (Academic, New York and London), (1959).
13. M. Chavez, V. Sosa, and R. Tsumura, J. Acoust. Soc. Am., 77, 420 (1985).
14. C. C. Chen and F. J. Millero, J. Acoust. Soc. Am. 60, 1270 (1976).
15. J. D. Bernal and R. H. Fowler, J. Chem. Phys., 1, 515 (1933).
16. H. S. Frank and W. Y. Wen, Discuss. Faraday Soc., 24, 133 (1957).
17. J. Morgan and B. E. Warren, J. Chem. Phys., 6, 666 (1938).
18. J. Lennard-Jones and J. A. Pople, Proc. Roy. Soc. London, Ser. A, 205, 155
(1951).
19. J. A. Pople, Proc. Roy. Soc. London, Ser. A, 205, 163 (1951).
20. D. N. Glew, J. Phys. Chem., 66, 605 (1962).
21. J. A. Barker, Ann. Rev. Phys. Chem., 14, 229 (1963).
22. G. Nemethy and H. A. Scheraga, J. Chem. Phys., 36, 3382 (1962).
Introduction
Page 28
23. H. S. Frank, Federation Proc.24, No.2, Part-ΙΙΙ, Supp. No.15, 1 (1965).
24. R. P. Marchi and H. Eyring, J. Phys. Chem., 68, 221 (1964).
25. G. Wada, Bull. Chem. Soc. Japan, 34, 955 (1961).
26. M. D. Danford and H. A. Levy, J. Am. Chem. Soc., 84, 3965 (1962).
27. P. Rajaguru and M. Jeyaraj, Acoustics Letters, 13, 142 (1990).
28. D. Vijayabhaskar Reddy, K. Ramanjaneyulu and A. Krishnaiah, Ind. J. Pure
and Appl. Phys., 28, 107 (1990).
29. N. G Belsare, V. P Akhare and V. S Deogaonkar, Acoustic Letters, 14, 37
(1990).
30. J. Govindappa, K. Rama Babu, P. Venkateswarlu and G. K Raman, Ind. J.
Pure and Appl. Phys., 28, 145 (1990).
31. P. Srinivasa Rao, M. C. S. Subha and G. Narayana Swamy, Acoustica, 75, 86
(1991).
32. U. Srinivasulu and P. Ramachandra Naidu, Ind. J. Pure and Appl. Phys., 29,
576 (1991).
33. C. Chennarayappa, K. Rambabu, P. Venkateshwarla and G. K. Raman,
Acoustics Letters, 15, 83 (1991).
34. D. P. Singh and B.C. Kalsh, Acoustics Letters, 14, 206 (1991).
35. R. K. Dewan, S. K. Mehta and S. T. Ahmad, Acoustics Letters, 15, 193
(1992).
36. V. Rajendran and J. Christopher Newton Benny, Acoustics Letters, 17, 33
(1993).
37. T. Ramanjappa, E. Murahari Rao and E. Rajagopal, Ind. J. Pure and Appl.
Phys., 31, 348 (1993).
38. P. Srinivasa Rao, Rajaramamohan Rao and G. Narayana Swamy, Acoustics
Letters, 16, 163 (1993).
39. C. Padmasree and K. Ravindra Prasad, Ind. J. Pure and Appl. Phys., 32, 954
(1994).
Introduction
Page 29
40. N. Yanadi Reddy, P. Subramanyam Naidu and K. Ravindra Prasad, Ind. J.
Pure and Appl. Phys., 32, 958 (1994).
41. T. Siva Prasad and P. Venkateswarlu, Acoustics Letters, 18, 5 (1994) .
42. J. D Pandey, P. Jain and V. Vyas, Pramana, 43, 361(1994).
43. K. C Kalra, K. C Singh and Umesh Bhardwaj, Ind. J. Chem., 33A, 314
(1994).
44. S. Chauhan, V. K. Syal and M. S. Chauhan, Ind. J. Pure and Appl. Phys.,
32,186 (1994).
45. B. K. Rout and V. Chakravortty, Ind. J. Chem., 33A, 303 (1994).
46. V. Rajendran and A. Marikani, Acoustics Letters, 18, 90 (1994).
47. C. Lafuente, J. Pardo, J. Santafe, F. M. Royo and J. S. Urieta, J. Chem.
Thermodynamics, 27, 541 (1995).
48. S. Chauhan, V. K Syal and M. S Chauhan, Ind. J. Pure and Appl. Phys., 33,
92 (1995).
49. P. S Nikam, M. C Jadhav and Mehdi Hasan, Ind. J. Pure and Appl. Phys., 33,
398 (1995).
50. M. S. Chauhan, K. C. Sharma, S. Gupta, M. Sharma and S. Chauhan,
Acoustic Letters, 18, 233 (1995).
51. Manisha Gupta and J. P. Shukla, Ind. J. Pure and Appl. Phys., 34, 769
(1996).
52. V Rajendran, Ind. J. Pure and Appl. Phys., 34, 52 (1996).
53. O. Bonner, J. Chem. Eng. Data, 27, 422 (1982).
54. R. Carta, J. Chem. Eng. Data, 44, 563, (1999).
55. E. L. Sexton and M. S. Dunn, J. Phys. Chem., 51, 648 (1947).
56. J. P. Amend and H. C. Helgeson, Pure and Appl. Chem., 69, 935 (1997).
57. F. J. Lo Millero, A. Surdo and C. Shin, J. Phys. Chem., 82, 784 (1978).
Introduction
Page 30
58. S. Cabani, G. Conti, E. Matteoli and A. Tani, J. Chem. Soc. Faraday Trans.,
I, 73, 476 (1977).
59. S. Cabani, G. Conti, E. Matteoli and M. R. Tine, J. Chem. Soc. Faraday
Trans., I, 77, 2377 (1981).
60. S. Cabani, G. Conti, E Matteoli and M. R. Tine, J. Chem. Soc. Faraday
Trans., I, 77, 2385 (1981).
61. F. Shahidi and P. G. Farrell, J. Chem. Soc. Faraday Trans., I, 74, 858 (1978).
62. D. P. Kharakoz, Biophys. Chem., 34, 115 (1989).
63. D. P. Kharakoz, J. Phys. Chem., 95, 5634 (1991).
64. A. Jolicoeur and J. Boileau , Can. J. Chem., 56, 2707 (1978).
65. A. A. Yayanos, J. Phys. Chem., 76, 1783 (1972).
66. A. A. Yayanos, J. Phys. Chem., 97, 13027 (1993).
67. R. Bhat and J. C. Ahluwalia, J. Phys. Chem., 89, 1099 (1985).
68. R. Bhat and J. C. Ahluwalia, Int. J. Peptide Protein Res., 30, 145 (1987).
69. T. S. Banipal and G. Sehgal, Thermochimica Acta, 262, 175 (1995).
70. A. Soto and M. Khoshkbarchi, Biophys. Chem., 74, 165 (1998).
71. A. Soto, A. Arce and M. K. Khoshkbarchi, Biophys. Chem., 76, 73 (1999).
72. A. K. Mishra and J. C. Ahluwalia, J. Chem. Soc. Faraday Trans., I, 77, 1469
(1981).
73. N. Taulier and T .V. Chalikian, Biochimica et Biophysica Acta , 1595, 48
(2002).
74. G. Singh and T. S. Banipal, Ind. J. Chem., 47A, 1355 (2008).
75. H. Zhao, Review Biophysical Chemistry, 122, 157 (2006).
76. A. Pal and N. Chauhan, Ind. J. Chem., 48A, 1069 (2009)
77. H. Uedaira, Bull. Chem. Soc. Jpn., 50, 1298 (1977).
Introduction
Page 31
78. R. Bhat, N. Kishore and J. C. Ahluwalia, J. Chem. Soc. Faraday Trans., I, 84,
2651 (1988).
79. H. L. Friedman, J. Chem. Phys., 32, 1134 (1960).
80. J. E. Mayer, J. Chem. Phys., 18, 1426 (1950).
81. D.Venkatesulu, P.Venkatesu and M.V. Prabhakararao, Phys. Chem. Liq., 32
127 (1996).
82. N.V. Sastry, M.C. Patel and S. Patel, Fluid Phase Equilib., 155, 261 (1996).
83. A. Ali, Abida, A. K. Nain and S. Hyder, J. Soln. Chem., 32, 865 (2003).
84. A .Moses, Ezhil Raj, L. B. Resmi, V. Bena Jothy, M. Jaychandran and C.
Sanjeeviraja, Fluid Phase Equilib., 282, 78 (2009).
85. Amalendu Pal and Gurucharan Das, J. Pure & Appl. Ultrasonics, 21, 9 (1990).
86. V.K.Syal, M.S.Chauhan, B.K.Chandra and S.Chauhan, J. Pure & Appl.
Ultrasonics, 18, 104 (1996).
87. G. Arul and L. Palaniappan, Indian J. Appl. Phys., 39, 561 (2001).
88. R. T. Lagemann and W. S. Dunbar, J. Phys. Chem., 49, 428 (1945).
89. D. S. Wankaede N.N Wankhede. M. K. Lande and B. R. Arbad, Indian
J. Pure & Appl. Phys., 44, 909 (2006).
90. M. Palaiologou, George. K. Arianas and Nikos. G. Tsierkezo J. Soln. Chem.,
35, 1551 (2006).
91. Ana B Pereiro and Ana Rodriguez, J. Chem. Eng. Data, 52, 600 (2007).
92. Ana Fransisca Ribeiro, Elisa Langa, A. M. Mainar, J. J. Pardo and J. S. Urieta,
J. Chem. Eng Data, 52, 1 (2006).
93. S. Nallani, S. Boodida and S. J. Tangeda, J. Chem. Eng. Data, 52, 405 (2007).
94. Monica Gepert and Barbara Stachowska, J. Soln. Chem., 35, 425 (2006).
95. V. K. Sharma and Satish Kumar, J. Soln. Chem., 34, 713 (2005).
96. S. J Kharat and P. S Nikam, J. Mol. Liq., 81, 13 (2007).
97. V. Kannappan, S. J. Askar Ali and P.A. Abdul Mahaboob, Indian J. Pure and
Appl. Phys., 44, 903 (2006).
98. Miroslow Chorozewski, J. Chem. Eng. Data, 52, 154 (2007).
99. S. Rodriguez, C. Lafuente, H. Artigal, F.M. Royo and J. S. Urieta, J. Chem.
Thermodyn., 31, 139 (1999).
Introduction
Page 32
100. M. Aravinthraj, C.Venkatesan and D. Meera, J. Chem. Pharm. Res., 3, 623
(2009).
