The effect of surface active agents in liquid extraction processes

Garner, F. H.; Hale, AR

doi:10.1016/0009-2509(53)80037-0

Cited by 95 publications

(36 citation statements)

References 11 publications

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“…The ability of surfactants to affect mass transfer by reducing internal circulation, oscillations, turbulence, and interfacial movement in drops has been used to explain the results of several experimental studies (Garner and Hale, 1953;Lewis, 1954). In many cases it is difficult to determine whether hydrodynamic effects or barrier effects are responsible for changes in mass transfer rates.…”

Section: Eflects Of Surfactants On Mass Transfermentioning

confidence: 98%

Effects of surfactants on mass transfer during spray drying

Frey

King

1986

AIChE Journal

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A study was conducted to investigate the effects of added surfactants on mass transfer during spray drying. Measurements were made of retention of volatile components and amount of water evaporation at various points near the atomizer inside a spray dryer of pilot plant scale. Experimental data indicate that surfactants can have a substantial effect on transport processes when certain types of liquid solutions are spray dried. Experimental results are interpreted in terms of transport mechanisms and are compared with relevant previous studies on nonspray systems. D. D. Frey C. J. King Department of Chemical EngineeringUniversity of California Berkeley, CA 94720 SCOPESpray drying is widely used for dehydration of liquid foods such as coffee and tea extracts, milk concentrates, and purees. Because of the economic importance of these products, and because of numerous other industrial applications of spray drying, there is growing interest in a better understanding of the mechanisms of mass transfer during spray drying. This knowledge should aid optimization of these processes for minimum cost, for better retention of volatile aroma components, and/or for improving other product quality factors.In spite of the large number of fundamental mass transfer studies to be described below, most previous work dealing with added surfactants has been on idealized systems and does not take into account the following complexities which are characteristic of industrial spray drying: Haven. CT 06520.3. Turbulence and oscillations in drops caused by 4. Effects of drying on the internal motions of drops 5. Formation of a surface crust or a selective-diffusion barrier Notwithstanding the relatively small amount of past work in this area, it is important to understand the effects of surfactants upon spray drying. Many or all liquid foods contain natural surfactants. In situations such as foam-spray drying, it may be necessary to add surfactants to the liquid feed to obtain the desired processing effect. Finally, addition of surfactants may be a convenient means to affect and control mass-transfer rates during spray drying or in other types of spray contacting.For these reasons, an experimental and theoretical investigation was undertaken of the spray drying of surfactant-containing aqueous sucrose and coffee solutions, with acetates as model aroma components. The principal aims of this investigation were to determine the effects of various surfactants on the retentions of highly volatile aromalike components and on the rate of water evaporation in regions close to the nozzle. An aerodynamic model of spray behavior was used to interpret the experimental results. CONCLUSIONS AND SIGNIFICANCEThis study indicates that surfactants can have a large effect on volatiles retention during spray drying. The primary effect of a surfactant appears to be on droplet hydrodynamics and particularly on oscillations, turbulence, and internal circulation in drops. In solutions of high solids content where volatiles losses from drops are small, surfactant...

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Section: Eflects Of Surfactants On Mass Transfermentioning

confidence: 98%

Effects of surfactants on mass transfer during spray drying

Frey

King

1986

AIChE Journal

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“…Ltd. for RO C2H4 (OC2H4)nOH of mean molecular weight 572), to the water the mass transfer rate is lowered to about 50% of the theoretical rate, since not only the turbulent tipples at the rear of the bubbles are suppressed, but the surface renewal due to circulation of the bubble is also eliminated [23]. This reduction of kL can be offset by the addition of few percent of short-chain alcohol or acetic acid [24][25][26].…”

Section: B} Mass Transfer Coefficientmentioning

confidence: 99%

Application of tower bioreactors in cell mass production

Schügerl

Lücke

Lehmann³

et al. 1978

Advances in Biochemical Engineering, Volume 8

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“…On the molecular level, the presence of surfactant molecules at a gas-liquid interface affects the mass transfer rate of a solute from the liquid to the gas by altering the interfacial region and providing additional resistance to diffusion through formation of a "condensed" layer of adsorbed surfactant [55,56]. Numerous studies have shown that the presence of adsorbed surfactant film at the interfaces retards the diffusion across interface in gas-liquid [57][58][59][60] and liquid-liquid systems [61][62][63]. Quantifying the individual mass transfer coefficients (i.e., k l , k m , and k g ) is beyond the scope of this study.…”

Section: Hollow Fiber Membrane Air-stripping Resultsmentioning

confidence: 99%