Chemical and Biomolecular Engineering - Research Publications

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    Mechanisms for the ultrasonic enhancement of dairy whey ultrafiltration
    Muthukumaran, S ; Kentish, SE ; Ashokkumar, M ; Stevens, GW (ELSEVIER SCIENCE BV, 2005-08-01)
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    The use of ultrasonic cleaning for ultrafiltration membranes in the dairy industry
    Muthukumaran, S ; Yang, K ; Seuren, A ; Kentish, S ; Ashokkumar, M ; Stevens, GW ; Grieser, F (ELSEVIER SCIENCE BV, 2004-10-01)
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    Operating temperature effects on the plasticization of polyimide gas separation membranes
    Duthie, X ; Kentish, S ; Powell, C ; Nagai, K ; Qiao, G ; Stevens, G (ELSEVIER SCIENCE BV, 2007-05-15)
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    Development of membrane testing protocols for characterisation of RO and NF membranes
    Northcott, K ; Kentish, SE ; Best, J ; Stevens, G (ELSEVIER, 2009-01-31)
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    Effect of surfactants on the rate of growth of an air bubble by rectified diffusion
    Lee, J ; Kentish, S ; Ashokkumar, M (AMER CHEMICAL SOC, 2005-08-04)
    The rectified diffusion growth of a single air bubble levitated in an acoustic field (frequency = 22.35 kHz) in water and in aqueous solutions containing surfactants (sodium dodecyl sulfate and sodium dodecylbenzene sulfonate) was investigated. As reported by Crum (J. Acoust. Soc. Am. 1980, 68, 203), the presence of surfactants at the bubble/liquid interface enhanced the growth rate of the bubble by rectified diffusion. It is suggested in this paper that in addition to the effect of surfactants on the surface tension and interfacial resistance to mass transfer, the effect of surface rheological properties may also contribute to the cause of the enhancement observed in the bubble growth rate.
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    Determination of the size distribution of sonoluminescence bubbles in a pulsed acoustic field
    Lee, J ; Ashokkumar, M ; Kentish, S ; Grieser, F (AMER CHEMICAL SOC, 2005-12-07)
    A simple method is described for determining the size of sonoluminescence bubbles generated by acoustic cavitation. The change in the intensity of sonoluminescence, from 4 ms pulses of 515 kHz ultrasound, as a function of the "off" time between acoustic pulses, is the basis of the method. The bubble size determined in water was in the range of 2.8-3.7 mum.
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    The dissolution of a stationary spherical bubble beneath a flat plate
    Kentish, S ; Lee, J ; Davidson, M ; Ashokkumar, M (PERGAMON-ELSEVIER SCIENCE LTD, 2006-12-01)
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    The use of ultrasonics for nanoemulsion preparation
    Kentish, S ; Wooster, TJ ; Ashokkumar, A ; Balachandran, S ; Mawson, R ; Simons, L (ELSEVIER SCI LTD, 2008-04-01)
    Oil-in-water emulsions are an important vehicles for the delivery of hydrophobic bioactive compounds into a range of food products. The preparation of very fine emulsions is of increasing interest to the beverage industry, as novel ingredients can be added with negligible impact to solution clarity. In the present study, both a batch and focused flow-through ultrasonic cell were utilized for emulsification with ultrasonic power generation at 20-24 kHz. Emulsions with a mean droplet size as low as 135±5 nm were achieved using a mixture of flaxseed oil and water in the presence of Tween 40 surfactant. Results are comparable to those for emulsions prepared with a microfluidizer operated at 100 MPa. The key to efficient ultrasonic emulsification is to determine an optimum ultrasonic energy intensity input for these systems, as excess energy input may lead to an increase in droplet size. Industrial relevance: The preparation of oil-in-water emulsions is a common feature of food processing operations. The use of ultrasound for this purpose can be competitive or even superior in terms of droplet size and energy efficiency when compared to classical rotor-stator dispersion. It may also be more practicable with respect to production cost, equipment contamination and aseptic processing than a microfluidisation approach. The present paper shows that ultrasound can be effective in producing nanoemulsions for use in a range of food ingredients.