scholarly journals Mass transfer effects in 2-D dual-permeability modeling of field preferential bromide leaching with drain effluent

2011 ◽  
Vol 8 (3) ◽  
pp. 5917-5967
Author(s):  
H. H. Gerke ◽  
J. Dusek ◽  
T. Vogel
Keyword(s):  
Mass Transfer ◽  
Preferential Flow ◽  
Mass Transfer Rate ◽  
Variable Mass ◽  
Chemical Properties ◽  
Small Scale ◽  
Transfer Coefficients ◽  
Permeability Model ◽  
Soil Matrix ◽  
Mass Transfer Coefficients

Abstract. Subsurface drained experimental fields are frequently used for studying preferential flow (PF) in structured soils. Considering two-dimensional (2-D) transport towards the drain, however, the relevance of mass transfer coefficients, apparently reflecting small-scale soil structural properties, for the water and solute balances of the entire drained field is largely unknown. This paper reviews and analyzes effects of mass transfer reductions on Br− leaching for a subsurface drained experimental field using a numerical 2-D dual-permeability model (2D-DPERM). The sensitivity of the "diffusive" mass transfer component on bromide (Br−) leaching patterns is discussed. Flow and transport is simulated in a 2-D vertical cross-section using parameters, boundary conditions (BC), and data of a Br− tracer irrigation experiment on a subsurface drained field (5000 m2 area) at Bokhorst (Germany), where soils have developed from glacial till sediments. The 2D-DPERM simulation scenarios assume realistic irrigation and rainfall rates, and Br-application in the soil matrix (SM) domain. The mass transfer reduction controls preferential tracer movement and can be related to physical and chemical properties at the interface between flow path and soil matrix in structured soil. A reduced solute mass transfer rate coefficient allows a better match of the Br− mass flow observed in the tile drain discharge. The results suggest that coefficients of water and solute transfer between PF and SM domains have a clear impact on Br− effluent from the drain. Amount and composition of the drain effluent is analyzed as a highly complex interrelation between temporally and spatially variable mass transfer in the 2-D vertical flow domain that depends on varying "advective" and "diffusive" transfer components, the spatial distribution of residual tracer concentrations, and the lateral flow fields in both domains from plots of the whole subsurface drained field. The local-scale soil structural effects (e.g., such as macropore wall coatings), here conceptualized as changes in mass transfer coefficients, can have a clear effect on leaching at the plot and field-scales.

Contribution of Liquid- and Gas-Side Mass Transfer Coefficients to Overall Mass Transfer Coefficient in Taylor Flow in a Microreactor

2014 ◽  
Vol 35 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Paweł Sobieszuk ◽  
Filip Ilnicki ◽  
Ryszard Pohorecki
Keyword(s):  
Mass Transfer ◽  
Mass Transfer Rate ◽  
Data Interpretation ◽  
Bubble Velocity ◽  
Transfer Coefficients ◽  
Channel Diameter ◽  
Transfer Resistance ◽  
Mass Transfer Coefficients ◽  
Taylor Flow ◽  
Rate Of Absorption

Abstract Gas-liquid microreactors find an increasing range of applications both in production, and for chemical analysis. The most often employed flow regime in these microreactors is Taylor flow. The rate of absorption of gases in liquids depends on gas-side and liquid-side resistances. There are several publications about liquid-side mass transfer coefficients in Taylor flow, but the data about gas-side mass transfer coefficients are practically non existent. We analysed the problem of gas-side mass transfer resistance in Taylor flow and determined conditions, in which it may influence the overall mass transfer rate. Investigations were performed using numerical simulations. The influence of the gas diffusivity, gas viscosity, channel diameter, bubble length and gas bubble velocity has been determined. It was found that in some case the mass transfer resistances in both phases are comparable and the gas-side resistance may be significant. In such cases, neglecting the gas-side coefficient may lead to errors in the experimental data interpretation.

scholarly journals Liquid-Liquid Equilibrium of Deep Eutectic Solvent-Aromatic-Aliphatic Ternary Systems: Experimental Study with COSMO Model Predictions

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1169
Author(s):  
Kyle McGaughy ◽  
M. Toufiq Reza
Keyword(s):  
Mass Transfer ◽  
Hydrogen Bond ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Transfer Coefficients ◽  
Liquid Equilibrium ◽  
Mass Transfer Coefficients ◽  
Cosmo Model ◽  
Lower Accuracy ◽  
Model Predictions

Common solvents used for aromatic extraction from aliphatics typically degrade into toxic compounds, while green alternatives perform poorly compared to the state-of-the-art solvents. Deep eutectic solvents (DES) are a novel solvent type made of hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA). DES have been applied in various applications, including advanced separations. In this study, DES were studied experimentally and using the Conductor-like Screening Model (COSMO) to separate benzene from cyclohexane as model compounds for an aromatic:aliphatic system. Both equilibrium and kinetic studies were performed to determine the liquid liquid equilibrium (LLE) and mass transfer rate for the DES-based separation. Selected HBAs including tetrabutylammonium bromide (N4444Br), tetrahexylammonium bromide (N6666Br), choline chloride (ChCl), and methyltriphenylphosphonium bromide (METPB) were paired with HBDs including ethylene glycol (EG) and glycerol (Gly). COSMO was used, with adjustments to reflect DES specific interactions, to predict the liquid-liquid equilibrium (LLE). COSMO results showed that ChCl and N6666Br-based DES extracted too little benzene or too much cyclohexane, respectively, to be considered for experimental evaluation. Overall, the COSMO model predictions for LLE of EG-based DES were very accurate, with root-mean-square deviations (RMSD) below 1% for both N4444Br:EG and METPB:EG. The glycerol systems were less accurately modeled, with RMSD’s of 4% for N4444Br:Gly and 6% for METPB:Gly. The lower accuracy of glycerol system predictions fmay be due to limitations in COSMO for handling glycerol’s influence on polarizability in the DES that is not seen in EG-based DES. Mass transfer kinetics were determined experimentally for DES and the results were fit to a first order kinetics model. METPB:Gly had the highest mass transfer coefficient at 0.180 min−1, followed by N4444Br:EG at 0.143 min−1. N4444Br:Gly and METPB:EG had the lowest mass transfer coefficients at 0.096 min−1 and 0.084 min−1, respectively. It was found that mass transfer rate was not directly related to maximum benzene solubility, as N4444Br:EG and METPB:Gly had the highest and lowest benzene removal, respectively, but had similar mass transfer coefficients.

Soil macropore-matrix mass exchange tracer experiments that account for sorption at macropore walls

2020 ◽  
Author(s):  
Horst H. Gerke ◽  
Jaromir Dusek ◽  
Martin Leue ◽  
Steffen Beck-Broichsitter ◽  
Martina Sobotkova ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Mass Exchange ◽  
Preferential Flow ◽  
Unsaturated Flow ◽  
Transfer Coefficients ◽  
Flow Paths ◽  
Soil Matrix ◽  
Specific Effects ◽  
The Matrix ◽  
Reactive Solutes

<p>The transfer of water and solutes between soil matrix and macropores controls preferential flow. Mass transfer depends on soil structural geometry and on properties of biopore walls and crack coatings that can differ from those of the matrix with respect to texture, organic matter, bulk density, and porosity. Agrochemicals and other solutes can react during transport along macropores, which has yet not been well-considered. The objective of this study was to study the specific effects of sorption on the reduction of mass exchange due to the effects of sorption at the macropore-matrix interface. Field and lab percolation experiments under unsaturated flow conditions were carried out with intact soil columns to simulate movement of bromide as a conservative and Brilliant Blue, iodide, and Na-Fluorescein as a reactive tracer. Sorption properties were determined separately for the biopore walls and crack coatings. The results suggest that preferential transport of reactive solutes depends even more strongly on the geometry and properties at flow paths surface than conservative solutes. If these properties can be determined, mass transfer coefficients in two-domain models can be related to soil structure and management.</p>

scholarly journals Scale-Up Studies for Co/Ni Separations in Intensified Reactors

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1106
Author(s):  
Dimitrios Tsaoulidis ◽  
Milan Mamtora ◽  
Marta Mayals Gañet ◽  
Eduardo Garciadiego-Ortega ◽  
Panagiota Angeli
Keyword(s):  
Mass Transfer ◽  
Scale Up ◽  
Plug Flow ◽  
Impinging Jets ◽  
Small Scale ◽  
Residence Times ◽  
Transfer Coefficients ◽  
Channel Diameter ◽  
Mass Transfer Coefficients ◽  
Cyanex 272

In this paper, the effect of the scalability of small-scale devices on the separation of Co(II) from a binary Co(II)/Ni(II) mixture in a nitric acid solution by an organic Cyanex 272/TBP/kerosene (Exxsol D80) phase is studied. In particular, circular channels with diameters of 1, 2, and 3.2 mm are considered. The results were compared against those from a confined impinging-jets (CIJ) cell with a main channel diameter of 3.2 mm. The effects of total flowrate, residence time, Cyanex 272 concentration, and flowrate ratio on the mass transfer performance were investigated. It was found that at increased channel size, the throughputs were also increased but the extraction percentages remained the same. Higher extraction percentages were obtained by using the CIJ configuration at short residence times. However, for longer residence times, the mass transfer coefficients were similar and capillary channels should be preferred over the CIJ because of the ease of separation of the two phases at the end of the unit. The overall mass transfer coefficients ranged between 0.02 and 0.14 s−1 for the capillary channels during plug flow and between 0.05 and 0.45 s−1 for the CIJ cells during dispersed flow.

Henry's constants and mass transfer coefficients of halogenated organic pollutants in an air stripping packed column

1998 ◽  
Vol 38 (6) ◽  
pp. 287-294 ◽  
Author(s):  
Pen-C. Chiang ◽  
Chung-H. Hung ◽  
J. C. Mar ◽  
E. E. Chang
Keyword(s):  
Mass Transfer ◽  
Methylene Chloride ◽  
Packed Column ◽  
Transfer Coefficients ◽  
Chlorinated Organic Compounds ◽  
Air Stripping ◽  
Mass Transfer Coefficients ◽  
Equilibrium Partition ◽  
Henry's Constants ◽  
Chlorinated Organic

Both Henry's constants and volumetric mass transfer coefficients (KLa) of eight priority chlorinated organic compounds including 1,1-dichloroethene, methylene chloride, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and 1,4-dichlorobenzene in an air stripping packed column were investigated in this study. The liquid and gas phase EPICS (Equilibrium Partition in Closed System) and direct calculating methods were applied to determine the Henry's constants of VOCs. The interference of co-solute on Henry's constants was also investigated. Experimental results indicated that decrease in Henry's constants of VOCs was observed in the presence of humic acid but no apparent effect on Henry's constants was detected when there was NaCl and surfactant in solution. Four different configurations of packing media including Intalox Saddle, Super Intalox Saddle, Telleret, and Hedgehog made of polypropylene were respectively packed in the air stripping tower and investigated in the study. The dependence of hydraulic loading, air-water ratio, and configurations of packing media on mass transfer coefficients of VOCs was discussed.

Transport of chlorinated hydrocarbons between sewage and sewer atmosphere

1996 ◽  
Vol 34 (3-4) ◽  
pp. 557-564 ◽  
Author(s):  
Bettina S. Haas ◽  
Reimer Herrmann
Keyword(s):  
Mass Transfer ◽  
Aromatic Compounds ◽  
Chlorinated Hydrocarbons ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Sewerage System ◽  
Mass Fluxes ◽  
Single Compound

Sewage containing volatile contaminants is a potential VOC-source in cities. Thus we tried to evaluate volatilization out of the sewerage system by measurements of contaminants in sewer gas and sewage. Our results from a medium sized town with little industry showed that sewer gas is mainly contaminated with alkanes, small aromatic compounds and chlorinated hydrocarbons. For three chlorinated hydrocarbons (chloroform, trichloroethene, tetrachloroethene) we determined mass transfer coefficients out of sewage and used these data to estimate mass fluxes from sewage and emissions out of the sewerage system for two sewer stretches. Considerable emission of chlorinated hydrocarbons from sewage, i.e. fluxes of some 10 to 100 g per m2·d, occurred only when the contaminant input via sewage was between some g and mg per litre for a single compound. For concentrations that were about 3 orders of magnitude less, emissions were negligible.

Mass Transfer in Liquid in an Apparatus with Mobile Packing. Application of a Dispersion Model

1993 ◽  
Vol 58 (5) ◽  
pp. 1078-1086
Author(s):  
Zdeněk Palatý
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Empirical Equation ◽  
Dispersion Model ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients

The paper deals with the mass transfer in a liquid on a plate with mobile packing. A procedure has been suggested which enables estimation of the mass transfer coefficients from experimental data considering the dispersion flow of the liquid. The results obtained from the desorption of CO2 from water are presented graphically and in the form of empirical equation.

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