ArticlePDF Available

Large Scale Sonochemical Processing: Aspiration and Actuality



It has been recognised for many years that power ultrasound has great potential in a wide variety of processes in the chemical and allied industries. Some of these processes have been known for many years and continue to flourish as major commercial applications, e.g. plastic welding and cleaning. Others, like ultrasonic drilling, while showing great potential have not been widely exploited to date. The potential for the industrial use of power ultrasound is enormous, and yet industry seems somewhat reluctant to adopt it. In this article the existing uses of power ultrasound in processing are reviewed and the potentials are explored.
Ultrasonics Sonochemistry 7 (2000) 145149
Large scale sonochemical processing: aspiration and actuality
Timothy J. Mason
Sonochemistry Centre, School of Natural and Environmental Sciences, Coventry University, Coventry CV1 5FB, UK
It has been recognised for many years that power ultrasound has great potential in a wide variety of processes in the chemical
and allied industries. Some of these processes have been known for many years and continue to flourish as major commercial
applications, e.g. plastic welding and cleaning. Others, like ultrasonic drilling, while showing great potential have not been widely
exploited to date. The potential for the industrial use of power ultrasound is enormous, and yet industry seems somewhat reluctant
to adopt it. In this article the existing uses of power ultrasound in processing are reviewed and the potentials are explored. © 2000
Elsevier Science B.V. All rights reserved.
Keywords: Cavitation; Industry; Power ultrasound; Reactor design; Sonochemistry; Transducer
1. Introduction key to sonochemical processing is acoustic cavitation,
but the secret of its success is the ability to control and
limit its eects to the reaction and not the reactor. ThisLarge scale processing using power ultrasound is not
a new concept. In the 1960s the industrial uses of power can often be achieved by focusing (concentrating) the
acoustic field within the liquid reaction medium.ultrasound were recognised [1,2]. There are many exam-
ples in the literature which also testify to this, for A further complication is the tendency of practi-
tioners to believe that increased input of acoustic powerexample a series of papers appeared in the journal
Ultrasonics back in the 1970s, entitled ‘Macrosonics in is related directly to increased yield or eect. This very
seldom holds true. There are many examples of an eectIndustry’ [3]. One of the more recent additions has been
a text translated from the Russian [4]. Progress over known as ‘decoupling’, where the eciency of transfer
of power from an ultrasonically vibrating source into athe last few years has been more rapid for two reasons:
firstly the greater general awareness of the possibilities liquid suddenly decreases above a certain level. Consider
for example the production of iodine from aqueous KIfor ultrasonic processing, and secondly the ever-widen-
ing span of applications which has attracted the atten- (Fig. 1) [5]. In this classic example the initial iodine
yield first increases in a relatively linear fashion abovetion and investment of more companies.
Whatever claims are made for sonochemical process- the cavitation threshold but then reaches a plateau for
a while before decoupling sets in and the yield dropsing, there remains one term used in its description which
is a turn-o for engineers that word is cavitation.
Certainly it is true that cavitation is normally considered
to be something to be avoided in the construction of
reactors. This is because erosion damage from hydrody-
namic cavitation (the type which aects propeller blades)
can cause problems to surfaces in contact with flowing
systems. In sonochemical processing the driving force is
acoustic (rather than hydrodynamic) cavitation, and
certainly there are many examples of surface damage
through acoustic cavitation. A typical example is the
pitting of aluminium foil when placed in the cavitating
liquid of an ultrasonic cleaning bath. Nevertheless, the
Fig. 1. The eect of ultrasonic power on iodine yield in the sonochemi-
* Tel.: +44-1203-838173; fax: +44-1203-838173. cal oxidation of I to iodine in aqueous solution.
1350-4177/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S1350-4177(99)00041-3
146 T.J. Mason / Ultrasonics Sonochemistry 7 (2000) 145–149
dramatically, despite the increased power supplied by an alloy of the rare earth elements terbium and dyspro-
sium with iron which is zone refined to produce athe transducer. Generally, for any sonochemical process,
there will be an optimum power for maximum eect. material almost in the form of a single crystal. It can be
produced in various forms, rods, laminates, tubes, etc.This will depend on a range of conditions, but will mean
that process optimisation can lead to a considerable and several major advantages have been claimed for this
material compared with the more conventional alloyssaving in overall economics of the process.
used, e.g. it can generate more power, it is more compact
(about 50% smaller) and also lighter than other magne-
tostrictives. Like other magnetostrictive materials,2. Ultrasonic transducers
Terfinol does has an upper limit of frequency response
of about 70 kHz.Whatever application of sonochemical processing is
to be studied and developed, one essential component Piezoelectric transducers are the most widely used
devices for the generation of ultrasound and can be usedof the system will be the transducer, of which there are
three main types. One is liquid driven and the other two over the whole range of ultrasonic frequencies. Current
developments using such transducers exploit their versa-are electromechanical; all of them have been in use for
many years. A fourth type of transducer has been tility in terms of both size and available frequency range.
Piezoelectric systems have been used to drive large andintroduced, the magnetically driven vibrating bar which
generates very high power vibrations in the audible powerful ultrasonic welders and cleaning baths, but are
also finding more refined uses in a new field of medicinefrequency range. This has some potential for heavy duty
processing and has been described elsewhere [6 ]. called therapeutic ultrasound [8]. One example of this
is the use of an extracorporeal array of transducers toLiquid whistles are particularly useful in applications
where homogenisation and ecient mixing are impor- produce a high intensity focus capable of destroying
tumours (HIFU ). Another is the use of a miniaturisedtant. Process material is forced under pressure generated
by a powerful pump through an orifice from which it ultrasonic device (1 MHz) attached to the end of a
catheter which can then be inserted into a blood vesselemerges, as a jet, into a mixing chamber. The jet impacts
upon a thin steel blade which is caused to vibrate and and used for the destruction of blood clots.
New possibilities exist for the development of piezo-thereby produce mixing of the process material flowing
over it. Additional mixing is produced through the electric devices using so-called 13 composites. These
consist of an array of piezoelectric pillars embedded inVenturi eect as the liquid rapidly expands into a larger
volume on exiting the orifice. There have been no a pliable material providing a transducer in the form of
a flexible sheet (Fig. 2) which can be moulded to fit thesignificant advances in the basic design of this type of
device in recent years, but the range of applications is shape of a reactor. A particular advantage of such a
system is that the emitting face is a combination ofbroad and new uses continue to emerge. Examples of
existing commercial processes include the preparation ceramic and plastic and can provide much better acoustic
transmission into aqueous systems.of soups, sauces, gravies and ketchup; in cosmetics
manufacture to make skin cream; and in textiles to There is also a great deal of interest in the production
of single crystal piezo material from a mixture of lead,increase the quality of dyeing in fabrics by improving
the general dispersion of the pigments. In the plastics zirconium and niobium compounds (from which they
get the name PZN ). Such single crystal transducersindustry, ultrasound has been used to disperse clay or
special thickening agents in polyester resin to give it the would provide low loss, high strain, low modulus and
have high coupling coecients. At the time of writingrequired characteristics. It can also be used to disperse
tinting pigments, which are mixed with the basic poly- these materials are not yet commercially available.
mer, a thickening agent and a solvent to produce the
coloured finish seen on most fibre glass products.
Magnetostrictive transducers use a property of certain
materials, e.g. nickel, which reduces in size when placed
in a magnetic field (magnetostriction) and then returns
to normal dimensions when the field is removed.
Improvements in the operating eciency of this type of
transducer have been based on finding a more ecient
magnetostrictive core. The original nickel alloys have
been replaced by more electrically ecient cobalt/iron
combinations and, more recently, aluminium/iron with
a small amount of chromium. One of the latest develop-
ments in magnetostrictive technology has been the intro-
Fig. 2. Schematic representation of a 13 piezoceramic array
duction of a new material called Terfinol-D [7]. This is
147T.J. Mason / Ultrasonics Sonochemistry 7 (2000) 145149
3. Industrial uses of power ultrasound biocide used in sterilisation, however, some bacteria are
capable of building up resistant strains which may
require a higher concentration. Power ultrasound aordsA selection of current uses of power ultrasound is
presented (Table 1). The first two of these are not driven the opportunity of increasing the eciency of existing
biocides through two major eects. Firstly the mechan-by acoustic cavitation, but the remaining fields generally
utilise cavitation to some extent. ical eects of cavitation can break down either bacterial
clumps or agglomerates of material to which the bacteria
adhere. This will remove the protection aorded to live3.1. Cleaning and decontamination
bacteria in the centre of the clumps or agglomerates.
Secondly ultrasound can increase the permeability ofUltrasonic cleaning is now such a well established
general technology that laboratories without access to biological cell walls so that the rate of uptake of the
biocide by the bacteria is ultrasonic cleaning bath are in a minority. Although
the laboratory ultrasonic cleaning bath is familiar, the A treatment system for the water in cooling towers
has been developed which involves a combination ofindustrial applications of such cleaning are perhaps less
well known. Ultrasonic cleaning can be either delicately ultrasound and electromagnetic radiation. The system,
registered under the name Sonoxide [10], tackles twoapplied for the cleaning of microcomponents under
clean room conditions or used for very large items such major drawbacks of cooling circuits, namely the build
up of algae and limescale. It is able to kill algae onas engine blocks in factories. It is particularly eective
in the removal of biological contamination because the exposure to ultrasound at a flow rate of 2 m3 h1 using
an acoustic power of only 450 W. The same low energycleaning action is through jets induced by cavitational
collapse on and near surfaces. These jets are easily requirement is sucient to take care of the problem of
the accumulation of limescale because it creates a formcapable of dislodging bacteria which may be adhering
to the surfaces. The particular advantage of ultrasonic of calcium carbonate crystal which does not settle as
scale. The crystals are carried away by the water in thecleaning in this context is that it can reach crevices that
are not easily reached by conventional cleaning methods. cooling circuit and separated using a hydrocyclone. The
major advantages of such treatment are its low energyFor this reason such cleaning is used for a range of
items from large crates used for food packaging to consumption, the elimination of the need for water
softening or biocidal chemicals, and also a large reduc-delicate surgical implements such as endoscopes.
Power ultrasound is currently under investigation for tion in the requirement for make-up water in the
cooling circuit.use in the biological decontamination of water [9].
Conventional methods of disinfection involve the use of A further possibility for environmental use of sono-
chemistry is in the treatment of sewage sludge.a biocide which, for the large scale water industry, is
commonly chlorine, chlorine dioxide or ozone. Current Anaerobic fermentation is the most commonly applied
process for stabilisation of sewage sludge and providestrends are towards the reduction in quantity of the
mass reduction, methane production, and improved
dewatering properties. A disadvantage of the fermenta-
Table 1
tion technique is that it is slow, with conventional
Some industrial uses for ultrasound
residence times in anaerobic digesters of about 20 days.
Field Application
Ultrasound has been used to accelerate the anaerobic
digestion of sewage sludge [11]. Ultrasonic treatment at
Welding Fabrication of thermoplastic articles and
a frequency of 31 kHz and high acoustic intensities at
welding of metals via specific heating at the
half technical scale shortened the residence time to eight
junction between the pieces
of material.
days with a biogas production 2.2 times that of a control
Cutting Accurate cutting of all forms of material
fermenter. Once optimised it is likely that this type of
from brittle ceramics to food products.
process will also be adopted on an industrial scale.
Atomisation Water sprays for dust suppression and
Ultrasonic irradiation has also been employed for
humidifiers, low velocity spray coating, spray
chemical remediation of water. The mode of sonochemi-
drying nozzles.
Cleaning and Cleaning of engineering items,
cal degradation of organic compounds in aqueous solu-
decontamination small electronic items and jewellery using
tion depends upon their physical and chemical
aqueous based solvents.
properties. This is because there are two ways in which
Cleaning and disinfection of medical
the cavitation bubble can function. In the case of volatile
instruments and food processing
chemicals which enter the bubble, destruction occurs
Processing Dispersion of pigments and powders
through the extreme conditions generated on collapse.
in liquid media and emulsification. Extraction,
In the case of chemicals remaining in the aqueous phase,
impregnation, crystallisation
the bubble acts as a source of radicals (H · ,HO· and
and filtration.
HOO · ) which enter the bulk solution and react with
148 T.J. Mason / Ultrasonics Sonochemistry 7 (2000) 145149
Table 2
pollutants. This is neatly illustrated in a comparative
Species employed for extractive value experiments
study of the decomposition of phenol (to carboxylic
acids) and carbon tetrachloride (to CO
and Cl)in
Plant species Main components Part of plant used
water saturated with oxygen at dierent frequencies
Foeniculum vulgare essential oils seeds
[12]. The results clearly show a dierence in the behavi-
(fennel )
our of the chemical contaminants, with the phenol
Humulus lupulus resin, essential oils female strobiles
degradation mirroring the peroxide formation, indicat-
ing that this reaction proceeds at the bubble interface
Calendula ocinale flavonoids, resin flowers
or outside the bubble. The volatile CCl
, however, is
Mentha piperita essential oils, pigments leaves
decomposed within the bubble and increased frequency
slightly accelerates the process.
On oshore oil drilling rigs an environmental problem
exists related to the disposal of drilling mud. This
material is a complex mixture of components which is of time with agitation, often in the form of tumbling.
Ultrasound has been shown to increase the rate ofinjected into the drill hole to serve as a lubricant and
flotation agent. After it has been used the mud, together penetration of the dye into the leather, and this oers
the commercially attractive possibility of attaining awith earth from the drill hole, is contaminated with oil
which must be thoroughly removed before the solids are more rapid turnover by reducing immersion times [15].
Since most of the processes in leather technology involvedumped at sea. Cleaning technologies exist for this, but
the cleaned material is then in the form of small agglom- liquid treatments and surface penetration, there are a
number of tanning processes which are under investiga-erates which, when dumped in the sea, sink to the sea
bed and accumulate around the platform legs. This tion with a view to increasing their eciency by
sonication.presents a problem to sea life and a hindrance to rig
maintenance. An ultrasonic device has been built for
the de-agglomeration of the cleaned mud on site, i.e. on 3.3. Crystallisation and precipitation
the rig. The equipment comprises four modules, each
one rated at 2 kW, and consisting of a stainless steel In conventional crystallisation techniques (e.g. in
penicillin production), a solution containing materialstube 1 m in length and 12 cm in diameter with an array
of piezoelectric transducers bonded to the outside, the to be crystallised is supersaturated either by cooling or
by evaporation and is then seeded. The problem withwhole enclosed in a casing [13]. The equipment provides
a flow treatment for the drilling mud which substantially seeding is that it may be initiated non-uniformly and
this can result in crystal growth proceeding at dierentreduces particle size. As a result, when the mud is
jettisoned from the oil rig it disperses across the sea bed rates at dierent nuclei sites. The resulting crystals may
then show a very broad and uneven crystal size distribu-and does not accumulate around the platform legs.
tion. It is also of considerable practical importance to
be able to control the onset of crystallisation in a large3.2. Extraction and impregnation
scale production process. Often it occurs in an uncon-
trolled manner simply due to a slight change in externalWhen cavitation bubble collapse occurs near a porous
material the jet which is generated is able to force liquid factors, such as a temperature or pressure fluctuation.
Ultrasound has proved to be extremely useful ininto the bulk material. This eect can be utilised to
enhance any process which involves either extraction or crystallisation processes since it can initiate seeding and
control subsequent crystal growth in a saturated orimpregnation of a liquid in a solid.
The classical techniques for the solvent extraction of supercooled medium. This is thought to be due to
cavitation bubbles themselves acting as nuclei for crystalchemical compounds from vegetable material are based
upon the correct choice of solvent and mixing condi- growth and to the disruption of seeds/nuclei already in
the medium, thus increasing the number of nuclei pre-tions, e.g. heating and agitation. A range of commer-
cially important pharmaceuticals, flavours and colorants sent. Through the correct choice of sonication conditions
it is possible to produce crystals of a uniform andare now derived from vegetable sources by solvent
extraction. One method of improving the extraction of designated size, which is of great importance in pharma-
ceutical preparations [16 ].organic compounds from within the body of plants and
seeds has been shown to be through the use of power Power ultrasound also has an additional property
which is particularly beneficial in crystallisation opera-ultrasound [14] (Table 2).
The same process of sonochemically forced impregna- tions, namely that the cleaning action of the cavitation
eectively stops the encrustation of crystals on coolingtion can be used to improve dying. The conventional
method for the dying of leather involves steeping the elements in the crystallisation vat and thereby ensures
continuous ecient heat transfer.material in an aqueous solution of the dye for a period
149T.J. Mason / Ultrasonics Sonochemistry 7 (2000) 145149
3.4. Electrochemistry 4. Conclusions
Aspirations for sonochemical processing are those
There are many examples of the large scale use of
which all production managers would welcome: faster
electrochemistry in industry, particularly in electroplat-
reactions, better conversions, improved and perhaps
ing, but most of them are not ecient in terms of
even new products. In truth there are many large
electrical power consumed. For some years there has
ultrasonic systems available and used in processing, but
been interest in the potential for improvement of such
few are optimised. There are now several multi-disciplin-
processes by the application of ultrasound
ary groups involved in sonochemical projects, and this
sonoelectrochemistry [17]. Electrochemical reactions are
is undoubtedly the way forward. The future for sono-
often complex but can be thought of as essentially the
chemical processing is therefore rosy, both from the
transfer of ions to and/or from the electrode surface.
point of view of greater interest in the fundamental
When an electrode is immersed in an aqueous solution
principles of its action, and in the development of
a thin diusion layer forms at the interface and, since
international programmes in applied research and
electrochemistry must involve ions crossing this layer,
any disturbance of it will influence that process. The jet
eect produced by cavitational collapse will reduce the
thickness of this diusion layer and assist diusion to
and from the electrode surface, which is often the
rate-controlling step. A number of beneficial sono-
[1] B. Brown, J.E. Goodman, High Intensity Ultrasonics, Ilie
electrochemical eects follow from this, including:
Books, London, 1965.
enhanced mass transport; altered adsorption phenomena
[2] J.R. Frederick, Ultrasonic Engineering, Wiley, London, 1965.
[3] E.A. Neppiras, Introduction, Macrosonics in IndustryUltrasonics
and surface eects; diminishing of electrode fouling;
10 (1972) 9.
manipulation of reaction mechanisms; production of
[4] O.V. Abramov, High-Intensity Ultrasound: Theory and Industrial
altered product distributions; increased yields and cur-
Applications, Gordon and Breach, London, 1998.
rent eciencies; improved synthetic routes; increased
[5] A. Henglein, M.J. Guitierrez, J. Phys. Chem. 94 (1990) 5169.
[6] J.P. Russell, M. Smith, Sonic energy in processing: use of a large
limiting current in analytical applications and lessened
scale, low frequency sonic reactor, in: T.J. Mason (Ed.), Advances
cell power requirements. Sonoelectrochemical methodol-
in Sonochemistry Vol. 5, JAI Press, Stamford, CA, 1999,
ogy can therefore oer considerable benefit for a range
pp. 279–302.
of dierent applications, including electroplating, syn-
[7] Information on Terfinol-D and applications of transducers uti-
lising this material may be obtained from Etrema Products Inc.,
thesis, analysis, environmental science, biotechnology,
2500 North Loop Drive, Ames, IA 50010, USA.
catalysis, sensor science and polymer synthesis [18,19].
[8] L. Crum, K. Hynynen, Physics World (1996) 28.
Although research in this field continues to be mainly
[9] S.S. Phull, T.J. Mason, The use of ultrasound in microbiology
on a laboratory scale, it is likely that industrial applica-
sonomicrobiology, in: T.J. Mason (Ed.), Advances in Sonochem-
istry Vol. 5, JAI Press, Stamford, CA, 1999, pp. 175208.
tions may be in place in the not too distant future.
[10] E. Cordemans, B. Hannecart, World Patent WO 98/01394, 1998.
[11] A. Tiehm, K. Nickel, U. Neis, Water Sci. Technol. 36 (1997) 121.
[12] C. Petrier, A. Francony, Ultrason. Sonochem. 4 (1997) 295.
3.5. Reactor design
[13] N. Avern, P.A. Copercini, World Oil (1997) 75.
[14] M. Vinatoru, M. Toma, T.J. Mason, Ultrasonically assisted
extraction of bioactive principles from plants and their constitu-
If sonochemical processing is to become more com-
ents, in: T.J. Mason (Ed.), Advances in Sonochemistry Vol. 5,
monplace in industry there will certainly be a need for
JAI Press, Stamford, CA, 1999, pp. 209248.
a stronger theoretical back-up to the work. In the past,
[15] J.-P. Xie, J.F. Ding, T.J. Mason, G.E. Attenburrow, J. Am.
using power ultrasound in a process was accepted if it
Leather Chem. Assoc. 94 (1999) 146.
[16 ] C. Price, Pharm. Technol. Euro. October (1997)
proved to be simply a better method than the existing
[17] T.J. Mason, J.P. Lorimer, D.J. Walton, Ultrasonics 28 (1990) 333.
technology. This is a good rationale, but often the
[18] D.J. Walton, S.S. Phull, Sonoelectrochemistry, in: T.J. Mason
sonochemical process used was not optimised. A much
(Ed.), Advances in Sonochemistry Vol. 5, JAI Press, Stamford,
greater input from chemical engineering and computer
CA, 1996, pp. 205284.
[19] R.G. Compton, J.C. Eklund, F. Marken, Electroanalysis 9
modelling will be needed in the design of the next
(1997) 509.
generation of sonochemical reactors [20]. With these
[20] J.-L.Y. Migeot, Proc. 16th Int. Congress on Acoustics/135th
new reactors will come the true scale up of processing
Meeting of Acoustical Society of America Vol. 3 (1998) 1539, see
also other papers in this special issue of Ultrasonics Sonochemistry.
and indeed of sonochemistry itself.
... Even then, it suffers from low efficiency [Michalke et al., 2002; Hassas-Roudsari et al., Yu et al., 2015]. A development in the neutraceutical extraction field has appeared in the form of ultrasound-assisted extraction [Vinatoru et al., 1997;Mason et al., 2000;Wu et al., 2001]. ...
... The probe was directly inserted into the sample vial so that the tip was fully immersed into the GLS solution. This direct sonication was employed to amplify the mechanical impact on large complex polysaccharides, enhancing their dissolution and extraction [Vinatoru et al., 2001;Mason et al., 2000;Wu et al., 2001]. Studies have shown a gain in neutraceutical yield from a higher proximity of the probe to the sample [Saleh et al., 2015]. ...
... most efficient" method is a not always relevant, nor practical. The literature review described numerous studies documenting the extraction of GLS using some traditional methods, and there is evidence supporting the efficiency of both solvent extraction and ultrasound-assisted extraction in extracting polysaccharides from GLS[Mason et al., 2000;Wu et al., 2001;Cares et al., 2010] -however it remains an area of intriguing research. ...
In recent decades the traditional Chinese medicinal mushroom Ganoderma lucidum (GL), a fungal specie widely consumed homoeopathically in the Eastern Hemisphere, has been studied particularly with respect to antitumour and immunoenhancing effects. Research into the various claims however remains limited owing to the lack of quality and consistency across investigations. As such, efficacy and feasibility of scaleup has not been evaluated in a way that allows widespread consumption or approved treatment. This project tackles three aspects of drug development from Ganoderma lucidum: Biocompound extraction, healthcare evaluation via in-vitro testing, and encapsulation for smart delivery. These avenues are brought together for the first time to evaluate the prospects of developing GL for effective and safe healthcare. This research investigates the parameters that would influence the extractability of a biocompound from the spores of Ganoderma lucidum (GLS), via two conventional methods: Hot Water Extraction (HWE) and Ultrasound-Assisted Extraction (UAE). They are evaluated with respect to their crude water-soluble polysaccharide yield (GLPS). Solvent polarity and process duration were statistically significant factors affecting extract yield, with both extraction methods showing considerable gains over similar setups in literature, recovering over 6% crude GLPS using shorter durations and lower temperatures than other published investigations. This investigation highlighted the importance of solvent viscosity on specific DGlucan extraction in the GLPS yield. Bioactive effects of the extract were evaluated via cytotoxicity toward Human Osteosarcoma (HOS) cells in-vitro, achieving over 40% cell growth inhibition. Cytotoxicity however was only achieved when water-insoluble fractions were administered – suggesting cytotoxicity was a result of the unextracted crude triterpenoids (GLTP) containing Ganoderic Acids. Therefore, HOS-inhibitory capabilities are then compared to a GLPS extract containing Ganoderic Acids (in this work termed “PSGA”), extracted using HWE subject to supervised machine learning optimisation. As well as determining that this yield was maximised at the longest HWE duration and smallest solvent volume, it was observed to inhibit HOS growth by nearly 58% after 24 hours. Low doses and shorter incubation were most effective - suggesting concepts such as resistance (clonal selectivity) and delayed apoptosis, but further work will verify the reported effects of PSGA dosage and exposure time on cancer proliferation. Lastly, research effort is devoted to creating an alginate matrix for the controllable delivery of GLS using Electrohydrodynamic Atomisation (EHDA). Significant effects of the system’s process parameters on particle morphology are observed, in particular EHDA voltage. The carrier’s size, shape and surface features are correlated with its release profile. Importantly, GLS content (something traditionally compromised to maintain particle integrity) was maximised at 50 wt% whilst maintaining a controlled and spherical shape and size – making this study novel and extremely important. It is established that GLS-Alginate particles could offer controlled release over a 2-week administration in pH-neutral conditions; an environment not yet established as “stable” for alginate, yet reflective of physiological passage. Thus, for the first time sodium alginate is proven to be a real contender in controlling the delivery of GLS biomolecules. The reconciliation of these essential stages of drug development highlights some crucial points of focus as GL continues to undergo rigorous development in the realm of drug discovery.
... The application of ultrasounds at large scales to promote electrochemical and sonoelectrochemical processes has been known since 1960, for the degradation of organic compounds and the treatment of sewage sludge (Mason, 2000). However, the use of sonochemical and ultrasound-assisted pathways for hydrogen production is currently under investigation only at laboratory and pilot scales. ...
... Mason (Mason, 2000) reported that transducers are essential components to consider when studying sonochemical processes. In addition, efficient transducers that ensure uniform cavitational activity at large scale are a major challenge (Gogate et al., 2011). ...
The present chapter tackles the topic of the sonochemical and ultrasound-assisted production of hydrogen from a multi-scale point of view. It starts from the state of the art of the processes known to lead to the formation of hydrogen while partially relying on either the physical, chemical or both effects of ultrasound, namely, the ultrasound-assisted processes for hydrogen production. It then focuses on the sonochemical pathway for hydrogen production by investigating the mechanisms explaining hydrogen emergence and inspecting their concordance with the experimental findings. The second section of the chapter aims to initiate the readers to a comprehensive methodology around the “properly speaking” ultrasound assisted production of H2. Finally, the chapter addresses the future of the sonolytic pathway of hydrogen production by questioning some macroscopic aspects related to energy, yields and technology. The final section discusses the perspectives of the technique by raising the most noticeable challenges and limitation known today, especially in terms of the greenness and sustainability.
... Despite its potential for industrial use [26][27][28], most sonochemical effects are studied at the laboratory scale. The challenge of designing cavitational reactors on an industrial scale is related to many problems, including the lack of precise quantification of the bubbles location and dynamic behaviour according to different operating and geometric conditions, the absence of appropriate design strategies connecting the theoretically available information (bubble dynamics) with the experimental results, and the unavailability of a trustworthy tool available to predict and design sonochemical reactors. ...
Full-text available
This investigation focuses on the influence of geometric factors on cavitational activity within a 20kHz sonoreactor containing water. Three vessels with different shapes were used, and the transducer immersion depth and liquid height were varied, resulting in a total of 126 experiments conducted under constant driving current. For each one, the dissipated power was quantified using calorimetry, while luminol mapping was employed to identify the shape and location of cavitation zones. The raw images of blueish light emission were transformed into false colors and corrected to compensate for refraction by the water-glass and glass-air interfaces. Additionally, all configurations were simulated using a sonoreactor model that incorporates a nonlinear propagation of acoustic waves in cavitating liquids. A systematic visual comparison between luminol maps and color-plots displaying the computed bubble collapse temperature in bubbly regions was conducted. The calorimetric power exhibited a nearly constant yield of approximately 70% across all experiments, thus validating the transducer command strategy. However, the numerical predictions consistently overestimated the electrical and calorimetric powers by a factor of roughly 2, indicating an overestimation of dissipation in the cavitating liquid model. Geometric variations revealed non-monotonic relationships between transducer immersion depth and dissipated power, emphasizing the importance of geometric effects in sonoreactor. Complex features were revealed by luminol maps, exhibiting appearance, disappearance, and merging of different luminol zones. In certain parametric regions, the luminol bright regions are reminiscent of linear eigenmodes of the water/vessel system. In the complementary parametric space, these structures either combine with, or are obliterated by typical elongated axial structures. The latter were found to coincide with an increased calorimetric power, and are conjectured to result from a strong cavitation field beneath the transducer producing acoustic streaming. Similar methods were applied to an additional set of 57 experiments conducted under constant geometry but with varying current, and suggested that the transition to elongated structures occurs above some amplitude threshold. While the model partially reproduced some experimental observations, further refinement is required to accurately account for the intricate acoustic phenomena involved.
... For an efficient design, the first step is understanding the mechanisms of interaction from the observed phenomena so that the desired cavitation field can be created on a larger scale to promote similar interactions. The important scaleup consideration is to establish the optimum conditions for the transformation in terms of the operating or design variables that influence the cavitation phenomena (Mason, 2000). In this analysis, the nature of the transformation also has an impact on the suitability of the given cavitational reactor. ...
... Considerable effort has been put into this aspect of ultrasonic engineering and a range of possibilities now exist. [10][11][12] In the food industry itself, the interest in the use of ultrasonics has grown to encompass a wide range of applications (Table 10.1). ...
This multi-authored book is edited by an expert in the field and includes chapters from international contributors. It is fully cross disciplinary relating green principles to the food industry, covering legal and policy issues, engineering, food processing and food science. It addresses the alternatives to conventional food processing that have reduced energy requirements or solvent use and how they affect final food quality. Initially, the principles of green chemistry and technologies are outlined to provide a justification and basis for the processing methods that are addressed. This is followed by a discussion of legal and policy issues in both the EU and the US which provide further justification for the need for such technologies and the constraints and benefits of current policies and regulations. The major green technologies available to the food industry are discussed, outlining the main principles and applications of each. The degree to which they are already in commercial use and developments needed to extend their use further are also covered.
In the present study, a novel designed ultrasound-equipped microchannel reactor has been used to improve the CO2 desorption process from aqueous N-methyldiethanolamine (MDEA) solutions. CO2 desorption rate for a microreactor without ultrasound irradiation was compared with an ultrasound-equipped one at various temperatures, flow rates, and ultrasound powers. The results revealed that ultrasound vibrations could facilitate CO2 desorption and cause a significant increase in the rate of that through generation of cavitation bubbles and turbulence. Evaluation of energy and mass transfer characteristics was performed; 37.8% energy saving and 144.2% increase in mass transfer coefficient was obtained using ultrasound at its maximum power compared to microreactor without ultrasound irradiation. Also, comparisons between the designed sono-microreactor and conventional methods for CO2 desorption were performed in terms of desorption energy consumption and mass transfer coefficient, indicating 40.9% energy saving compared to 30 wt% MEA benchmark process and 160 times increase in mass transfer coefficient. Due to its high performance in terms of energy saving and mass transfer enhancement compared to the conventional method, the newly designed sono-microreactor can be introduced as a highly efficient technique for solvent regeneration.
Full-text available
Over the last few years, many scientists and engineers have formed an interest in sonochemistry associated with production and processes for the application of power ultrasound. Literature with remarkable outcomes using sonochemistry are enormous but rarely accepted within the scientific community due to two factors, namely specific resistance toward ideas producing sound energy that is used as a driving force for chemical modifications and insufficient equipment for scaling-up activities. The energy provided through ultrasound is known to considerably enhance the production and quality of product facilitating purification and recovery processes for varied industrial items. There are varied fields where there will be high progress in sonochemistry in near future but more of them would be in smaller scale. Outstanding laboratory results are continuously thriving for scaling up of the existing systems. Higher collaboration and cooperation amongst interested scientific fields for effective application of cavitation principle due to ultrasonication are needed now.
Multibubbles in a cavitation reactor are subjected to both external and mutual acoustic radiation forces. The radiation forces by a plane traveling wave, a standing wave, and radiating waves between bubbles are described. These forces influence the spatial distribution, the kinetics of bubble clustering, and bubble coalescence in the cavitation reactor, which in turn directly impacts the reactor performance. Recent developments showed that measurement of acoustic radiation energy from a multibubble cavitation field could be adapted for quantitative analysis of cavitation number density and size distribution. Further development of this approach has the potential to transform how sonochemical reactors will be designed and how cavitation processes can be scaled and optimized in the future.
The slow degradation rate of sewage sludge in anaerobic digesters is due to the rate limiting step of sludge hydrolysis. The effect of ultrasound pretreatment on sludge degradability was investigated using ultrasound at a frequency of 31 kHz and high acoustic intensities. Ultrasound treatment resulted in raw sludge disintegration as was demonstrated by increase of Chemical Oxygen Demand in the sludge supernatant and size reduction of sludge solids. Semi-continuous fermentation experiments with disintegrated and untreated sludge were done for four months on a half-technical scale. One fermenter was operated as a control with a conventional residence time of 22 days. Four fermenters were operated with disintegrated sludge and residence times of 22, 16, 12, and 8 days, respectively. In the fermenters operated with identical residence times of 22 days reduction of volatile solids was 45.8% for untreated sludge and 50.3% for disintegrated sludge. The fermentation of disintegrated sludge was stable even at the shortest residence time of 8 days with biogas production 2.2 times that of the control fermenter. Due to ultrasound disintegration a better degradability of raw sludge was achieved that permitted a substantial increase in throughput.
MOST of us who have recently become parents are familiar with the use of ultrasound in medicine. We have seen "baby's first picture" and thrilled to the ghost-like images of the head, the beating heart and perhaps even the face. These images are produced by ultrasound: a transducer projects high-frequency sound waves into the uterus and collects the reflected waves, which are then used to build up an image.
Application of power ultrasound (18kHz - IMHz) to leather processing has become more viable due to (I) increased commercial availability and advances of ultrasound technology, (2) the apparent applicability of ultrasound across the whole breadth of "wet" processes in leather manufacturing, and (3) tightened environmental legislation which demands new efficient processing technology. Thus power ultrasound (38 kHz, 1.36 W cm-2) has been employed in our systematic investigations on a number of leather processes. In this first part of a series of papers, the effects of power ultrasound on leather dyeing and the factors influencing the effectiveness of ultrasonic dyeing, such as timing, mechanical agitation, temperature, type of dyes, type of leather and dye concentration, have been investigated. It was found that ultrasonic dyeing can increase the degree of dye penetration by 50-120%, shorten the process time by 40-70%, facilitate low temperature dyeing or allow a reduction of the dye offer by 30%. In addition, it can also improve the color fastness particularly to wet rubbing. This remarkable enhancing effect is attributed mainly to an increased diffusion coefficient of dyestuff in leather in the presence of power ultrasound. The results have shown that ultrasound is best applied in the initial stage of the dyeing for a short period of time and is most effective for a dyeing system which has difficulty in achieving high dye exhaustion or penetration. It was found that ultrasound is more effective than mechanical stirring and can be combined with mechanical agitation in accelerating the dyeing process. The influence of temperature is system dependent and there exists an optimal temperature for maximizing the effectiveness of 'ultrasonic dyeing.
The slow degradation rate of sewage sludge in anaerobic digesters is due to the rate limiting step of sludge hydrolysis. The effect of ultrasound pretreatment on sludge degradability was investigated using ultrasound at a frequency of 31 kHz and high acoustic intensities. Ultrasound treatment resulted in raw sludge disintegration as was demonstrated by increase of Chemical Oxygen Demand in the sludge supernatant and size reduction of sludge solids. Semi-continuous fermentation experiments with disintegrated and untreated sludge were done for four months on a half-technical scale. One fermenter was operated as a control with a conventional residence time of 22 days. Four fetmenters were operated with disintegrated sludge and residence limes of 22, 16, 12, and 8 days, respectively. In the fermenters operated with identical residence times of 22 days reduction of volatile solids was 45.896 for untreated sludge and 50.3% for disintegrated sludge. The fermentation of disintegrated sludge was stable even at the shortest residence time of 8 days with biogas production 2.2 times that of the control fermenter. Due to ultrasound disintegration a better degradability of raw sludge was achieved that permitted a substantial increase in throughout.
The oxidation of iodide and main-chain degradation of poly(acrylamide) were studied under continuous and pulsed 1-MHz ultrasound irradiation of aqueous solutions containing both solutes simultaneously. The ratio of the rates of degradation to oxidation strongly increases with the intensity of the ultrasound. In the intensity range where the coalescence of cavitation bubbles causes the oxidation yield to diminish, the degradation is little affected. It is concluded that strong shear forces (producing fast degradation) are still generated in the vicinity of oscillating or collapsing gas bubbles when the temperature reached in the adiabatic compression phase of the bubbles is not high (i.e., little oxidation occurs). A high ratio of polymer degradation to iodide oxidation was also found in the irradiation with intense 20-kHz ultrasound from a commercial generator (horn diameter 14 mm). It is concluded that free-radical side effects, such as oxidations, are relatively unimportant when 20-kHz ultrasound is used to mechanically rupture large structures.