Interfacial area measurement

Coughlin and von Berg [Chem. Eng. Sci., 21, 3 (1966)]. Continuous heat transfer and extraction of ethylbiityric acid between kerosine and water unbaffled vessel, Pump-Mix design (Fig. 15-28). Interfacial area measured. 

Auxiliary data are the sizes of bubbles and droplets. These data and the holdups of the two phases are measured by a variety of standard techniques. Interfacial area measurements utihze techniques of transmission or reflection of light. Data on and methods for finding sohi-bihties of gases or the relation between partial pressure and concentration in hquid are also well estabhshecT... 

Interfacial area measurement. Knowledge of the interfacial area is indispensable in modeling two-phase flow (Dejesus and Kawaji, 1990), which determines the interphase transfer of mass, momentum, and energy in steady and transient flow. Ultrasonic techniques are used for such measurements. Since there is no direct relationship between the measurement of ultrasonic transmission and the volumetric interfacial area in bubbly flow, some estimate of the average bubble size is necessary to permit access to the volumetric interfacial area (Delhaye, 1986). In bubbly flows with bubbles several millimeters in diameter and with high void fractions, Stravs and von Stocker (1985) were apparently the first, in 1981, to propose the use of pulsed, 1- to 10-MHz ultrasound for measuring interfacial area. Independently, Amblard et al. (1983) used the same technique but at frequencies lower than 1 MHz. The volumetric interfacial area, T, is defined by (Delhaye, 1986)... 

S.A. Patel, J.G. Daly, D.B. Bukur, Holdup and interfacial area measurements using dynamic gas disengagement, AIChE J. 35 (1989) 931-942. 

The specific interfacial areas measured by pure oxygen absorption were expressed as a function of the total specific power dissipated in the liquid as follows ... 

The gas-liquid interfacial area measured form the physical techniques is generally about 35% higher than the one measured by the chemical technique. The chemical technique is generally more accurate than the physical technique. The reaction systems described in Table XXXI are reliable for the gas-liquid system. For gas-liquid-solid systems, the method is not reliable even when solids are inert, because of possible adsorptions of gas and/or liquid on the solid surface. 

The interfacial area can be measured in specific systems using chemical reactions in which the absorption rate kinetics are a known function of the gas-liquid interfacial area. For example, Vasquez et al. (2000) compared three different chemical methods (i) Danckwerts method using the absorption of CO2 in sodium or potassium carbonate buffer solutions, (ii) the sodium sulfite method involving the oxidation of sulfite ions, and (iii) the sodium dithionite method involving the oxidation of dithionite ions. All three methods were shown to produce similar interfacial area measurements. 

Another interesting example is polycondensation reactions to procedure polyesters and polyamides (73). Sharma (3,4) discusses also some aspects of interfacial polycondensation here, for instance, the diacyl chloride, dissolved in a water immiscible organic solvent, may be contacted with hexamethylene diamine to proceduBs the polyamide. Nylon 66. Since diamine is very soluble in the organic phase and the reaction is very fast, the reaction occurs probably in organic phase, therefore acyl chloride cannot get an opportunity to get into aqueous phase where concurrent hydrolysis would have occured Usually, a film of polymer is formed on the organic phase droplets disposed in water and thus droplets are encapsulated and interfacial area measurements can well be envisaged. 

Holdup, bubble size and interfacial area. Measurements on gas holdup and bubble sizes are hardly to be found for hydrocarbons at higher temperatures. Only recently were gas holdup data and bubble sizes... 

Raghuram PT. (2007) Interfacial area measurement in a gas liquid ejector. Ind. J. Chem. Tech., 16 278-282. 

The interfacial tension is the difference between the actual Helmholtz energy per unit interfacial area, measured on a plane normal to z, and that which the system would have if the properties of the bulk phases on both sides of the interface were constant up to a plane located so as to satisfy a condition of zero surface excess of matter... 

Xue J, Al-Dahhan M, Dudukovic MP, Mudde RF (2008) Bubble velocity, size, and interfacial area measurements in a bubble column by four-point optical probe. AIChE J 54(2) 350-363... 

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