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Showing papers on "Mass transfer coefficient published in 2009"


Journal ArticleDOI
TL;DR: The present work is aimed at the reviewing of the oxygen transfer rate (OTR) in bioprocesses to provide a better knowledge about the selection, design, scale-up and development of bioreactors.

1,203 citations


Journal ArticleDOI
TL;DR: Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model and significant increases in initial adsorption rate were observed with the increase in temperature followed by pH and initial MB concentration.

503 citations


Journal ArticleDOI
TL;DR: In this article, the effect of initial dye concentration, contact time, adsorbent dose, stirring speed, pH, salt concentration and temperature were studied in batch mode using commercially available kaolin to adsorb two different toxic cationic dyes namely crystal violet and brilliant green from aqueous medium.

406 citations


Journal ArticleDOI
TL;DR: In this paper, a two-dimensional stationary model based on the universal conservation laws and coupled with electrochemical reactions is applied to describe a single all-vanadium redox flow cell.

270 citations


Journal ArticleDOI
TL;DR: In this paper, a new empirical correlation has been proposed to describe mass transfer data in this microchannel, and an appropriate modification has been made to this correlation in order to improve its applicability in microchannels.

156 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of spacer geometry on fluid dynamics and mass transfer in feed channels of spiral wound membranes has been investigated, and three-dimensional computational fluid dynamics (CFD) simulations reveal significant influence of the spacer geometric parameters such as filament spacing, thickness, and flow attack angle on wall shear rates and Mass Transfer coefficients.

147 citations


Journal ArticleDOI
TL;DR: In this article, a film-pore diffusion model has been used to predict the fixed-bed breakthrough curves for each of the four metal ions in a single component adaption system.

146 citations


Journal ArticleDOI
TL;DR: In this paper, a model was established to illustrate the mechanism of gas-liquid mass transfer with reactions in rotating packed bed at higher gravity level, and experiments were carried out at various rotating speeds, liquid flow rates, gas flow rates and temperatures in RPB with Benfield solution as the absorbent.

135 citations


Journal ArticleDOI
TL;DR: In this paper, a hollow-fiber contactor was applied to carbon dioxide stripping from monoethanolamine (MEA) solution at high temperature where most polymeric membranes would fail to operate.

133 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of the structure on the diffusion coefficient is taken into account by introducing an effective diffusion coefficient, which is calculated using the Bruggeman approximation for the through-plane and in-plane diffusibility in the diffusion layer of PEM fuel cells.
Abstract: The understanding of mass transport limitations in polymer electrolyte membrane (PEM) fuel cells is crucial in the research and progress of this technology. The structure of the components, specifically the as diffusion layer (GDL), of PEM fuel cells, is complex. Thus, for the purpose of simulating mass transport in the GDL, the effect of the structure on the diffusion coefficient is taken into account by introducing an effective diffusion coefficient. The effective diffusion coefficient of a gas is lower than its corresponding bulk diffusion coefficient due to the presence of a solid matrix in the porous materials. Currently, the Bruggeman approximation is the most widely used correlation for estimating the effective diffusion coefficient in the GDL. Other semiempirical models are also available. However, these correlations overestimate the effective diffusion coefficient due to the assumptions on which they are based. In this study, correlations for the through-plane and in-plane diffusibility in the GD...

126 citations


Journal ArticleDOI
TL;DR: Air stripping of ammonia from water with Ca(OH)2 was performed in the newly designed gas-liquid contactor, a water-sparged aerocyclone (WSA), which exhibited a higher air stripping efficiency and an excellent mass transfer performance, and consumed less air compared with stripping tanks and packed towers.

Journal ArticleDOI
TL;DR: It was found that adsorption kinetics of phenol can be very well represented by the pseudo-second order equation and the film mass transfer coefficient obtained from the analysis of breakthrough curves for small particle size and short bed at applicable conditions agreed fairly well with that obtained from mass transfer correlation available in literature.

Journal ArticleDOI
TL;DR: In this paper, the inert gas is used to agitate two immiscible fluids in microchannels, and the mass transfer performance with or without gas agitation is investigated, which is in the range of 3.8-30.6 s−1.
Abstract: in this experiment, the inert gas is used to agitate two immiscible fluids in microchannels. the mass transfer performances with or without gas agitation are investigated. 30% tbp (in kerosene)-acetic acid-water is chosen as testing system. and nitrogen as agitating gas. the superficial velocities of the immiscible liquid-liquid two phases and gas phase are varied in the range from 0.02 to 1.2 m/s, and 0 to 3.0 m/s. respectively. in microchannels, with enough gas agitating intensity. high dispersion between two immiscible liquid phases can be obtained. the overall volumetric mean mass transfer coefficients are two-folds higher than those without gas agitating, which are in the range of 3.8-30.6 s(-1). some parameters which impact on the mass transfer process, such as the mixture superficial velocity of the immiscible liquid-liquid two phases, the gas superficial velocity, the microchannel structure, the gas inlet locations and the sampling time are experimentally investigated. (c) 2009 american institute of chemical engineers aiche j, 55: 1948-1958, 2009

Journal ArticleDOI
TL;DR: In this paper, the PSRI benchmark challenge problem was modeled using kinetic theory based CFD with the energy minimization multi-scale (EMMS) drag law, and the mass transfer coefficients and the Sherwood numbers were estimated based on particle cluster sizes.

Journal ArticleDOI
TL;DR: Results indicate that ultrasound enhances the mass transport in the pores as well as across the boundary layer with increasing ultrasonic power for the three studied frequencies.

Journal ArticleDOI
TL;DR: In this article, the behaviour and mass transfer of N-methyldiethanolamine (MDEA) in the removal process of carbon dioxide using a bubble column reactor (BCR) as gas-liquid contactor was analyzed.

Journal ArticleDOI
TL;DR: The research showed that the SCNT reactor is promising because of its energy efficiency and has potential for application in wastewater treatment.
Abstract: A seepage carbon nanotube electrode (SCNE) reactor was designed in order to facilitate contaminant mass transfer from bulk solution to the electrode surface, therefore to break the high cost bottleneck of electrochemical wastewater treatment. The innovative concept behind the reactor design is that the overall mass transfer would be significantly improved via contaminant migration through the porous carbon nanotube electrode. It was found out that the surface diffusivity D(s,i) in the external film was the controlling coefficient for electrochemical treatment, and the proposed process could improve the overall mass transfer coefficient by 116-161% compared with conventional electrochemical reactors under the same conditions. The research also showed that the current efficiency of the SCNE reactor was 340-519% higher than that of conventional reactors, and the energy consumption to mineralize the same amount of organics was only 16.5-22.3% of the conventional reactors. Also, the influences of potential, pH, and electrolyte concentration were investigated to optimize the operating parameters for the SCNE reactor. These results show that the SCNT reactor is promising because of its energy efficiency and has potential for application in wastewater treatment

Journal ArticleDOI
TL;DR: In this paper, the authors present a method for numerical simulation of conjugate mass transfer of a dilute species with resistance in both phases and an arbitrary equilibrium distribution coefficient, based on the volume-of-fluid technique and accounts for the concentration jump at the interface by transforming the discontinuous physical concentration field into a continuous numerical one.

Journal ArticleDOI
TL;DR: In this article, the Sips, Elvoich and Dubinin-Radushkevich, Redlich-Peterson, Langmuir four types and Ho's four types of pseudo-second-order kinetic models were fitted to the equilibrium data.

Journal ArticleDOI
TL;DR: In this paper, the effect of surfactants on liquid side mass transfer coefficients is investigated based on the determination of the liquid side transfer coefficient k L at a free gas-liquid interface, under controlled temperature and hydrodynamic conditions.

Journal ArticleDOI
TL;DR: In this article, the authors measured the transient mass transfer coefficient and average mass transfer coefficients for a rectangular channel with and without air sparging and found that the dependency of mass transfer on bubble size and frequency has two regions, an increasing region and a plateau region.

Journal ArticleDOI
TL;DR: In this paper, Wang et al. utilized the concept of internal or intraphase mass transfer coefficient to simplify the problem of diffusion and reaction in more than one spatial dimension for a washcoated monolith of arbitrary shape.

Journal ArticleDOI
TL;DR: In this paper, the adsorption performance of copper on calcium alginate encapsulated magnetic sorbent is investigated via equilibrium and kinetics study, and the results showed that the sorption performance is greatly affected by the initial solution pH, the background ionic strength, the mechanical stirring speed, and presence of humic acid.

Journal ArticleDOI
TL;DR: In this paper, the mass transfer coefficient of the FFAs esterification reaction with methanol, catalyzed by ionic-exchange sulphonic acid resins, was investigated in different reactor configurations on a model mixture composed by artificially acidified soybean oil with oleic acid using an acid exchange resin as catalyst.

Journal ArticleDOI
TL;DR: In this paper, a commercial activated carbon was functionalized with 3-chloropropylamine hydrochloride and its adsorption characteristics in a fixed-bed column were investigated.
Abstract: It has been reported that the CO2 adsorption capacity of the N-enriched activated carbon can increase or decrease. In this study a commercial activated carbon was functionalized with 3-chloropropylamine hydrochloride and its adsorption characteristics in a fixed-bed column were investigated. The N-enriched activated carbon presented lower BET surface area than the original activated carbon suggesting that the nitrogen incorporation partially blocks the access of N2 to the small pores. Although the surface basicity has increased it is not accomplished by an increase of the capacity of the adsorption of the N-enriched activated carbon. The breakthrough curves in a fixed bed column were obtained at different temperatures (301 K, 323 K, 373 K, and 423 K) and a total pressure of 1.01 bar using CO2 diluted in helium at two feed concentrations—10% and 20% (v/v). A model based on the Linear Driving Force (LDF) model for mass transfer was used to estimate the overall mass transfer coefficient and reproduced the br...

Journal ArticleDOI
TL;DR: A general reduced HETP (height equivalent to a theoretical plate) equation is proposed that accounts for the mass transfer of a wide range of molecular weight compounds in monolithic columns and variable degrees of systematic peak fronting are exhibited, depending on the column studied.

Journal ArticleDOI
TL;DR: In this article, the cathode potential on the gas-evolving electrode in 0.5 M H 2 SO 4 solution was measured under a uniform magnetic field and the current interrupter method was used to study the IR-drop and the supersolubility of dissolved hydrogen gas.

Journal ArticleDOI
TL;DR: Li et al. as discussed by the authors predicted micro-bubble dissolution characteristics in water and seawater when microbubbles are generated by a Sadatomi-type micro-bubble generator with a spherical body in a flowing liquid tube.

Journal ArticleDOI
TL;DR: In this paper, a methodology is proposed for the determination of these coefficients using variable drying parameters (lag factor, k 0 and drying coefficient, k ) mixed-mode solar dryer with potato cylinders and slices was used to obtain variable (temperature dependent) k0 and k from drying kinetics.

Journal ArticleDOI
TL;DR: In this article, a new formulation of two-phase flow with interphase mass transfer is proposed based on thermodynamic principles, which comprises a mass balance for each component in each phase and a mass imbalance for specific interfacial area.
Abstract: Interphase mass transfer in porous media takes place across fluid–fluid interfaces. At the field scale, this is almost always a kinetic process and its rate is highly dependent on the amount of fluid–fluid interfacial area. Having no means to determine the interfacial area, modelers usually either neglect kinetics of mass transfer and assume local equilibrium between phases or they estimate interfacial area using lumped parameter approaches (in DNAPL pool dissolution) or a dual domain approach (for air sparging). However, none of these approaches include a physical determination of interfacial area or accounts for its role for interphase mass transfer. In this work, we propose a new formulation of two-phase flow with interphase mass transfer, which is based on thermodynamic principles. This approach comprises a mass balance for each component in each phase and a mass balance for specific interfacial area. The system is closed by a relationship among capillary pressure, interfacial area, and saturation. We compare our approach to an equilibrium model by showing simulation results for an air–water system. We show that the new approach is capable of modeling kinetic interphase mass exchange for a two-phase system and that mass transfer correlates with the specific interfacial area. By non-dimensionalization of the equations and variation of Peclet and Damkohler number, we make statements about when kinetic interphase mass transfer has to be taken into account by using the new physically based kinetic approach and when the equilibrium model is a reasonable simplification.