Cavitation techniques

Sivakumar M, Pandit AB (2002) Wastewater treatment A novel energy efficient hydrodynamic cavitational technique. Ultrason Sonochem 9 123-131... 

In heterogeneous liquid/liquid reactions, cavitational collapse at or near the interface will cause disruption and mixing, resulting in the formation of very fine emulsions. When very fine emulsions are formed, the surface area available for the reaction between the two phases is significantly increased, thus increasing the rates of reaction. The emulsions formed using cavitation, are usually smaller in size and more stable, than those obtained using conventional techniques and often require little or no surfactant to maintain the stability [8]. This is very beneficial particularly in the case of phase-transfer catalyzed reactions or biphasic systems. 

Fig. 2.10 Classification of different types of techniques for understanding cavitational activity distribution...

In the case of a venturi flow, the most economical technique for increasing cavitation intensity would be to reduce the length of venturi, but for higher volumetric flow rates there could be a limitation due to the possibility of flow instability and super-cavitation. A similar argument can be given for the enhancement in the cavitation intensity by reducing the venturi throat to pipe diameter ratio. 

The above two studies with actual contaminated water (possibly containing a wide range of bacteria/microorganisms) confirm the suitability of the hydrodynamic cavitation phenomena for microbial disinfection. Cost of the treatment is another important factor, which needs to be ascertained, before cavitation can be recommended as a replacement technique for the conventional methods of... 

The similarity between the mechanism of destruction and some of the common optimum operating conditions in the case of different advanced oxidation techniques point towards the synergism between these methods and fact that combination of these advanced oxidation processes should give better results as compared to individual techniques [70]. This indeed is applicable to hydrodynamic cavitation as well and there have been reports where hydrodynamic cavitation has been combined with other advanced oxidation processes with great success. 

Ambulgekar GV, Samant SD, Pandit AB (2005) Oxidation of alkylarenes using aqueous potassium permanganate under cavitation Comparison of acoustic and hydrodynamic techniques. Ultrason Sonochem 12 85-90... 

Patil MN, Pandit AB (2007) Cavitation-A novel technique for nano-suspensions/nanoemul-sions. Ultrason Sonochem 14 519-530... 

Gogate PR (2008) Treatment of wastewater streams containing phenolic compounds using hybrid techniques based on cavitation a review of the current status and the way forward. Ultrason Sonochem 15 1-15... 

Ultrasonic irradiation of a liquid leads to the generation of cavitation phenomenon which comprised of unique reaction fields in addition to physical and mechanical effects the formation of micro-meter sized bubbles, formation of bubbles with high temperature and high pressure conditions, formation of shock waves, and strong micro-stirring effects are produced. Table 5.1 shows representative ultrasound techniques to synthesize inorganic and metal nanoparticles and nanostructured materials. 

Cavitation bubble pyrolysis technique Fe, Fe/Co, M02C, CoFe204 [8-10]... 

Sonochemical reduction technique using reductants formed from hot cavitation bubbles Au, Pd, Pt, Ag, Ru, Au/Pd [9]... 

SnO has received much attention as a potential anode material for the lithium-ion-secondary-battery. The conventional techniques require temperatures above 150°C to form phase pure SnO. Whereas, sonication assisted precipitation technique has been used to prepare phase-pure SnO nanoparticles at room temperature by Majumdar et al. [25]. In this study, ultrasonic power has been found to play a key role in the formation of phase pure SnO as with a reduction in the ultrasonic power authors have observed a mixed phase. For the case of high ultrasonic power, authors have proposed that, intense cavitation and hence intense collapse pressure must have prevented the conversion of SnO to Sn02-... 

Physical Chemist who specializes in Sonochemistry, teaches undergraduate and postgraduate Chemistry and is a senior academic staff member of the School of Chemistry, University of Melbourne. Ashok is a renowned sono-chemist who has developed a number of novel techniques to characterize acoustic cavitation bubbles and has made major contributions of applied sonochemistry to the Food and Dairy industry. His research team has developed a novel ultrasonic processing technology for improving the functional properties of dairy ingredients. Recent research also involves the ultrasonic synthesis of functional... 

The comparison between pore sizes evaluated by Hg intrusion and N2 volumetry for MCM-41 and SBA-15 samples are reported in Fig. 3. The data obtained from the two techniques coincide for MCM-41, while Hg intrusion underevaluates the pore size of the SBA-15 samples. The Washbum-Laplace model (Fig. la) [1] does not account for the cavitation effects in the retraction of Fig [9], which are taken into account by the Kloubek-Rigby-Edler model (Fig. lb) [2], The pore size evaluated by N2 adsorption is not affected by the defects of the pore walls of SBA-15, as these defects have already been filled when capillary condensation takes place [10]. 

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