Mass transfer coefficients in a hanson mixer-settler extraction column

In the present work, multistage extraction column performance for reactive separation of molybdenum from the leach aqueous phase by using D2EHPA and TBP in kerosene was investigated by using axial diffusion model. Initially, the values of initial pH and extractant concentration were optimized on the batch experiments. The variation of volumetric overall mass transfer coefficients based on continuous phase at various operating conditions was obtained. By considering the chemical reaction conditions, the experimental data indicate that the volumetric overall mass transfer coefficients increase with an enhancement in rotor speed and continuous and dispersed phase flow rates. According to the sensitivity analysis, the rotor speed and flow rate of dispersed phase have more influence on column performance. Also, the continuous flow rate has little effect on volumetric overall mass transfer coefficients. After the steady-state condition was established, the concentration profile for the extraction of molybdenum along the column was obtained. The experimental data were studied and compared with the previous models. A new model based on dimensionless numbers was derived from the evaluation of overall mass transfer coefficients with consideration of the reactive extraction system.

Liquid- liquid countercurrent extraction of 3% 2,3-butanediol from aqueous solution was carried out using 3-methyl-1-butanol as extracting solvent in presence of 10% sodium carbonate. Study of effect of dispersed phase flow rate and continuous phase flow rate was carried out. Overall mass transfer coefficient was found to increase with dispersed phase flow rate but there is practically no effect of continuous phase flow rate on it. For 3% BD in feed 90% extraction was achieved at solvent to feed ratio of 5, Number of theoretical stages of 1.102 was found to be established during extraction. A run was made using 15% of BD containing 10% sodium carbonate at continuous phase velocity of 0.531 cm/sec and dispersed phase velocity of 2.655 cm/sec corresponding to solvent to feed ratio of 5. Overall mass transfer coefficient of 1.060 X10 -3 Sec -1 was obtained corresponding to 94.16% extraction. Number of theoretical stages was found to be 1.292. Hence it is more economical to work with a feed containing up to 15% BD

This study presents a three-dimensional transient computational fluid dynamics simulation of droplet generation in a flow-focusing microfluidic device using the coupled level set and volume of fluid method for interface capturing. We systematically investigated the effects of shear-thinning non-Newtonian fluids, specifically carboxymethyl cellulose solutions, on the generation of mineral oil droplets. The rheological properties of carboxymethyl cellulose were analyzed at concentrations of 0.1%, 0.25%, 0.5%, and 1.0%, with the parameters K and n specified in terms of viscosity. The study examines the influence of rheological properties, continuous and dispersed phase flow rates, and interfacial tension forces on the generation and dynamics of controlled high-throughput droplets. The numerical results provide insight into droplet characteristics, including droplet length, velocity, formation frequency, liquid film thickness, pressure distribution, and flow regimes. The findings revealed that increasing the carboxymethyl cellulose concentration (0.1%–1.0%) and continuous phase flow rate (10–30μl/min) reduces droplet length by 53% and 45%, respectively, while increasing the dispersed phase flow rate (2–18 μl/min) and interfacial tension results in increased droplet length by 62% and 42%. At lower concentrations of carboxymethyl cellulose, plug-shaped droplets fully occupy the channel width in the squeezing regime. As concentration increases, a transition to the dripping and jetting regimes is observed. The study further explores non-dimensional parameters, expressing the Weber and modified Capillary numbers as functions of flow rate and interfacial tension. These insights impact drug delivery, material synthesis, and microfluidic technologies requiring precise droplet control.

ABSTRACTThe present work aimed to optimize the lanthanum extraction efficiency in the pilot-scale asymmetric rotating disc contactor. Optimal batch-scale extraction conditions were determined for the preparation of feed for extraction column (D2EHPA 0.08 mol/L; pH~8). In continuous mode, the optimization with the central composite design approach was performed by using three main parameters, such as continuous phase flow rate, agitation intensity, dispersed phase flow rate. Three responses studied were slip velocity, dispersed phase holdup, and extraction efficiency. The higher value of extraction efficiency for lanthanum extraction shows the main effect of agitation intensity on the dispersed phase holdup, slip velocity, and rate of mass transfer. The optimum conditions for extraction efficiency equal 98.5% were obtained at a rotation speed equal to 7.75 1/s, and phase flow rates equal to 1.25 × 10−5 m3/s. The new correlations are estimated to describe the holdup of the dispersed phase and the slip velocity with high accuracy and R-square values equal to 0.9734 and 0.9670, respectively. The results showed that the pilot plant asymmetric rotating disc column could be used as an appropriate column for the lanthanum extraction from aqueous solution as an example of rare earth metals.

Mass transfer coefficients—calculation for rigid and oscillating drops in extraction columns

Numerical simulation of flow behavior of particles in a gas-solid stirred fluidized bed

Formation dynamics and size prediction of bubbles for slurry system in T-shape microchannel

Microfluidic technology is attracting the attention from researchers and is currently applied in many fields such as biology, pharmaceuticals and chemistry. This technology is considered to have many advantages over traditional methods, including time saving, sample volume reduction and cost effectiveness. The goal of this study was to investigate the effects of rib shapes on droplet generation process in a T-junction microchannel. By using a three-dimensional (3D) laminar model with the Volume Of Fluid (VOF) based on ANSYS FLUENT software, numerical models of T-junction with rib was proposed to predict fluid phenomena at the microscale. This study showed that the droplet size could be affected by the flow rate of continuous phase and flow rate of dispersed phase. In addition, the rib shapes in T-junction significantly impacted the droplet size, which helps to optimize the droplet generation. These small ribs of different shapes can be manufactured by using photolithography techniques. These results will therefore contribute significantly to the fabrication of high-precision microfluidic devices. The ability to control the droplet size in a T-junction through rib shapes not only improves the efficiency and reliability of microfluidic systems but also extends the potential for new significant applications in various scientific fields. In conclusion, this research not only highlights the advantages of this technology but also lays the foundation for further exploration of the optimization and performance enhancement of microfluidic devices. The insights gained from this study into the relationship between rib shapes and droplet generation were important contributions to the design and manufacturing of next-generation microfluidic devices.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGas-liquid interfacial area and liquid-side mass-transfer coefficient in a slurry bubble columnEizo Sada, Hidehiro Kumazawa, Choul Ho Lee, and Hiroaki NarukawaCite this: Ind. Eng. Chem. Res. 1987, 26, 1, 112–116Publication Date (Print):January 1, 1987Publication History Published online1 May 2002Published inissue 1 January 1987https://pubs.acs.org/doi/10.1021/ie00061a022https://doi.org/10.1021/ie00061a022research-articleACS PublicationsRequest reuse permissionsArticle Views449Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The present work aims to evaluate the hydrodynamics of a pulsed packed extractor, with an internal diameter of 0.026m and a length of 1.0m, using the liquid butanol-water system. Thus, the basic parameters obtained for the hydrodynamic study of the extraction column in question as dispersed phase, slip velocity, characteristic velocity and flooding point. The methodology used in the work consisted of determining the holdup fraction of the dispersed phase, obtained through tests of simultaneous interruptions in the column feedings. The effects of frequency pulsation, dispersed phase flow rate and continuous phase flow rate investigated in the analysis of these parameters. New empirical correlations derived from the predictions of the parameters studied obtained in terms of operating variables and physical properties of the liquid system involved. The average absolute value of the relative error (AARE) was always below 5.6%. Good agreement between calculated and experimental results observed for all investigated operating conditions.

Flow rates and mean hold-ups of solids have been measured under the counter-current flow of water in a 50 mm in diameter vibrating perforated plate column. Experimental data have been described by a mathematical model expressing the specific flow rate of solids in dependence on the hold-up, terminal velocity of the particles, porosity of the plate, specific flow rate of the continuous phase and the frequency and amplitude of plate vibrations. It has been found that for systems exhibiting low particle terminal velocity the pumping effect of the plates may increase the flow rate of the dispersed phase to a value corresponding to the flow in the empty column.

Mass transfer coefficient determination in three biphasic systems (water–ionic liquid) using a modified Lewis cell

An experimental breakthrough curve for Salicylic acid in an adsorption recovery process was determined by an anion-exchange resin IRA-93. The volumetric mass transfer coefficients were calculated by employing constant wave propagation theory. Meanwhile, the effects of volumetric feed flow rates on this break through curve and mass transfer coefficients at different flow rates were also studied in order to develop three new models to predict mass transfer coefficient. The results demonstrated that by the increase in the feed flow rates, the amount of adsorption reduces. However, while the volumetric feed flow rates increase the overall volumetric mass transfer coefficients will increase. This grows the feeling that the feed flow rate should be optimized. The optimum flow rate for the adsorption was found to be 7 mg/l in this study. In addition, three new models to predict the mass transfer coefficient in respect of feed rates were developed in this research work which showed very high fittings with R2>0.99. These models could fully support the experimental data obtained.

Removal of tributyl phosphate from aqueous stream in a pilot scale combined air-lift mixer-settler unit: Process intensification studies

In this work, gas dispersion in a two-phase partitioning bioreactor is analyzed by calculating volumetric oxygen mass transfer coefficient which is modeled using a commercial computational fluid dynamics (CFD), code FLUENT 6.2. Dispersed oxygen bubbles dynamics is based on standard "k-ε" Reynolds-averaged Navier-Stokes (RANS) model. This paper describes a three-dimensional CFD model coupled with population balance equations (PBE) in order to get more confirming results of experimental measurements. Values of k L a are obtained using dynamic gassing-out method. Using the CFD simulation, the volumetric mass transfer coefficient is calculated based on Higbie's penetration theory. Characteristics of mass transfer coefficient are investigated for five configurations of impeller and three different aeration flow rates. The pitched six blade type, due to the creation of downward flow direction, leads to higher dissolved oxygen (DO) concentrations, thereby, higher values of k L a compared with other impeller compositions. The magnitude of dissolved oxygen percentage in the aqueous phase has direct correlation with impeller speed and any increase of the aeration magnitude leads to faster saturation in shorter periods of time. Agitation speeds of 300 to 800rpm are found to be the most effective rotational speeds for the mass transfer of oxygen in two-phase partitioning bioreactors (TPPB).