Simulation and experimental analysis of mass transfer in a liquid-liquid stirred tank extractor

Ahn, Byoung Sung; Lee, Won Kook

doi:10.1021/ie00105a027

Cited by 5 publications

(4 citation statements)

References 15 publications

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“…Indeed in this test, the phenomenon of methanol drawdown in oil was practically instantaneous, and the influence of interfacial mass-transfer was considered very small, on the basis of the analysis illustrated in section 3.1; the observed initial reaction rate was therefore assumed to be an acceptable approximation of the actual rate of chemical reaction. The evaluation of the parameters and mass-transfer coefficients contained in the expressions of t T,NP , t T,P and t D,P , derived from refs − , is illustrated in the Supporting Information. The Sauter mean diameter ( d 32 ) relative to each configuration at the beginning of the reaction test was estimated on the basis of eq , thus neglecting the evolution of d 32 from the initial value to the stationary value provided by eq . ,,, This choice implies an underestimate of the mass-transfer resistance during the initial part of the reaction.…”

Section: Resultsmentioning

confidence: 99%

Optimization of Mechanical Agitation and Evaluation of the Mass-Transfer Resistance in the Oil Transesterification Reaction for Biodiesel Production

Frascari

Zuccaro

Paglianti

et al. 2009

Ind. Eng. Chem. Res.

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The KOH-catalyzed transesterification of sunflower oil with methanol was studied in batch conditions in a 22 L stirred reactor in order to (i) develop criteria for the energetic optimization of mechanical agitation in the biodiesel synthesis reaction; (ii) obtain preliminary information on the decantation of the reaction products; (iii) evaluate the influence of the mass-transfer resistance under different mixing conditions. Different combinations of radial, axial, and pitched-blade impellers were tested. For each combination an optimal rotational speed was identified, characterized on the one hand by a drastic reduction of the specific mixing energy, and on the other by a 20−30% increase of reaction time. An evaluation of the reaction and mass-transfer characteristic times showed that the optimized tests are characterized by a not negligible mass-transfer resistance. The complete halt of the agitation after a 1−2 min mixing time led to a further decrease of mixing energy, without any increase of reaction time. Preliminary decantation tests showed that the individuation of an optimized agitation speed for the reaction step, combined with the agitation halt after a short mixing time, has positive effects on the liquid−liquid separation step. The results were compared with those of a twin study conducted with static mixing.

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Section: Resultsmentioning

confidence: 99%

Optimization of Mechanical Agitation and Evaluation of the Mass-Transfer Resistance in the Oil Transesterification Reaction for Biodiesel Production

Frascari

Zuccaro

Paglianti

et al. 2009

Ind. Eng. Chem. Res.

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“…Information deficiencies with respect to the specific interfacial areas involved in such reactor systems prevents a direct determination of the film transfer coefficient, although values can be estimated using system-specific correlations (4,5,15,16). Information deficiencies with respect to the specific interfacial areas involved in such reactor systems prevents a direct determination of the film transfer coefficient, although values can be estimated using system-specific correlations (4,5,15,16).…”

Section: Introductionmentioning

confidence: 99%

“…Deviations exceeding a factor of 2 have been noted in a few instances however (10,13,14 Liquid-liquid mass transfer in packed columns, in slurry systems, and in dispersed liquid-liquid systems is typically described in terms of a lumped mass transfer coefficient, which is given in turn by the product of the film transfer coefficient and the specific interfacial area. Information deficiencies with respect to the specific interfacial areas involved in such reactor systems prevents a direct determination of the film transfer coefficient, although values can be estimated using system-specific correlations (4,5,15,16). In contrast, mass transfer in non-dispersed liquid-liquid systems having easily quantifiable specific interfacial areas can be described more directly in terms of film mass transfer coefficients.…”

Section: Introductionmentioning

confidence: 99%

Mass Transfer of Polynuclear Aromatic Hydrocarbons from Complex DNAPL Mixtures

Mukherji

Peters

Weber

1997

Environ. Sci. Technol.

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Parameters governing the rates of mass transfer of the individual components of four synthetic dense non-aqueous phase liquid (DNAPL) mixtures into the aqueous phase were evaluated. The DNAPL mixtures, composed of toluene and eight polynuclear aromatic hydrocarbons (PAHs), were designed to serve as models for coal tars and creosotes. The reactor employed provided a relatively stable interface between internally mixed but segregated aqueous and DNAPL phases. Two parameters, the aqueous phase concentration at equilibrium and the overall film mass transfer coefficient, were quantified by simulating aqueous concentration profiles with a mass-transfer-limited rate model using a statistical parameter search and data fitting routine. DNAPL phase activity coefficient values for the various compounds derived from equilibrium aqueous phase concentrations were typically within a factor of 2 of Raoult's law prediction of unity; refinement of fugacity ratio estimates for the solid PAHs brought the values even closer to unity. Film transfer coefficients for all components of the mixtures studied were similar in magnitude, in the range 0.8-3 × 10 -3 cm/s. No significant variations of the film transfer coefficient for naphthalene were noted across the DNAPL mixtures, over which the mole fraction of this compound was varied from 0.05 to 0.25.

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“…The distribution of the solutes between the NAPL and the aqueous phase is governed by the hydrodynamic conditions and the molecular diffusion of solutes in both the phases and the interphases. The kinetics of solute dissolution from NAPLs has been extensively studied, and several mass transfer models derived theoretically and empirically have been previously published (Ahn and Lee 1990; Alshafie and Ghoshal 2004;Benhabib et al 2006;Cho et al 2005;Chrysikopoulos et al 2003;Ghoshal et al 2004;Lee 2004;Lee et al 2007;Mukherji et al 1997;Schluep et al 2001). Critical reviews of recent work on NAPL dissolution in porous media have indicated that the most promising research progress, in addition to exploitation of combined large-scale field and computational investigations (Broholm et al 2005), may be determined by the clarification of the role of nonideal NAPL mixtures and identification of intra-NAPL mass transfer processes (Khachikian and Harmon 2000).…”

Section: Introductionmentioning

confidence: 99%

Contaminant Mass Transfer from NAPLs to Water Studied in a Continuously Stirred Flow-Through Reactor

et al. 2012

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The release of nonaqueous-phase liquids (NAPLs) from porous media to groundwater is a widespread environmental problem. The mass transfer of individual NAPL components controls both the extent of groundwater contamination and the persistence of the residual NAPL phase. In order to quantify this key process, small-scale experimental studies on NAPL-water mass transfer were performed in a dynamic system mimicking environmental conditions with "clean" water continuously flowing through the NAPL pool. To describe this process, a modified simulation method was developed and validated by the experimental data. The experimental system consisted of a custom-designed flow cell (with NAPL and water) connected to the peripheral equipment (e.g., pump, water source). This continuously stirred flow-through reactor was used to perform mass transfer experiments with simple and complex model NAPL-water systems. To simulate the experimental data (concentration versus time profiles of individual NAPL compounds), an analytical solution of a standard mass transfer model was adapted in simple model NAPL systems, and a numerical method was employed for complex multicomponent model NAPL-water systems containing phenols, heteroaromatic compounds, and polycyclic aromatic hydrocarbons (PAHs). The numerical model was developed based on a mass balance equation and a general form of Raoult's law. The simulated concentration profiles of the various solutes matched well the experimental data only if the nonideal behavior of the more polar solutes was accounted for. Using the developed numerical mode simulated mass transfer coefficients for individual NAPL components compared well with previously published values if available.

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Simulation and experimental analysis of mass transfer in a liquid-liquid stirred tank extractor

Cited by 5 publications

References 15 publications

Optimization of Mechanical Agitation and Evaluation of the Mass-Transfer Resistance in the Oil Transesterification Reaction for Biodiesel Production

Optimization of Mechanical Agitation and Evaluation of the Mass-Transfer Resistance in the Oil Transesterification Reaction for Biodiesel Production

Mass Transfer of Polynuclear Aromatic Hydrocarbons from Complex DNAPL Mixtures

Contaminant Mass Transfer from NAPLs to Water Studied in a Continuously Stirred Flow-Through Reactor

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