scholarly journals Analysis of Mass Transport through Anisotropic, Catalytic/Bio-Catalytic Membrane Reactors

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 358 ◽  
Author(s):  
Endre Nagy ◽  
Márta Vitai
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Mass Transport ◽  
Convective Flow ◽  
Variable Mass ◽  
Transport Processes ◽  
Biochemical Reaction ◽  
Transport Parameter ◽  
Membrane Layer ◽  
Mass Transport Process

This paper investigated the steady-state mass transport process through anisotropic, composite membrane layers with variable mass transport coefficients, such as the diffusion coefficient, convective velocity, or chemical/biochemical reaction rate constant. The transfer processes can be a solution-diffusion model or diffusive plus convective process. In the theoretical part, the concentration distribution as well as the inlet and outlet mass transfer rates’ expressions are defined for physical transport processes with variable diffusion or solubility coefficients and then that for transport processes accompanied by first- and zero-order reactions, in the presence of diffusive and convective flow, with constant and variable parameters. The variation of the transport parameters as a function of the local coordinate was defined by linear equations. It was shown that the increasing diffusion coefficient or convective flow induces much lower concentrations across the membrane layer than transport processes, with their decreasing values a function of the space coordinate. Accordingly, this can strongly affect the effect of the concentration dependent chemical/biochemical reaction. The inlet mass transfer rate can also be mostly higher when the transport parameter decreases across the anisotropic membrane layer.

Electrochemical Removal of Copper and Lead from Industrial Wastewater: Mass Transport Enhancement

2009 ◽  
Vol 44 (2) ◽  
pp. 183-188 ◽  
Author(s):  
Asim Yaqub ◽  
Huma Ajab ◽  
Saqib Khan ◽  
Sajjad Khan ◽  
Robina Farooq
Keyword(s):  
Mass Transfer ◽  
Energy Consumption ◽  
Mass Transport ◽  
Diffusion Layer ◽  
Industrial Wastewater ◽  
Lead Nitrate ◽  
Electrochemical Treatment ◽  
Bulk Solution ◽  
Metallic Ions ◽  
Mass Transport Process

Abstract The effects of ultrasonic frequencies on both the mass transport process and diffusion layer were investigated during electrochemical treatment. The rates of mass transfer at a stainless steel cathode were measured for copper and lead in dilute acidified copper sulphate and lead nitrate solutions at different ultrasonic frequencies. Concentrations in bulk solution were determined by atomic absorption spectrophotometer. By increasing frequencies from 40 to 100 kHz, a high value for the mass transfer coefficient and an effective thinning of the diffusion layer were observed. Higher rates of mass transfer reduced energy consumption. Use of ultrasound with electrochemical processes can provide valuable contributions to remove metallic ions from industrial wastewater without using extra chemicals. The process has efficiently reduced the cost of energy consumption and deposition time.

scholarly journals Application of Paramagnetically Tagged Molecules for Magnetic Resonance Imaging of Biofilm Mass Transport Processes

2010 ◽  
Vol 76 (12) ◽  
pp. 4027-4036 ◽  
Author(s):  
B. Ramanan ◽  
W. M. Holmes ◽  
W. T. Sloan ◽  
V. R. Phoenix
Keyword(s):  
Magnetic Resonance Imaging ◽  
Diffusion Coefficient ◽  
Magnetic Resonance ◽  
Mass Transport ◽  
Diffusion Model ◽  
Transport Processes ◽  
Resonance Imaging ◽  
Phototrophic Biofilm ◽  
Dimensional Diffusion ◽  
Wide Range

ABSTRACT Molecules become readily visible by magnetic resonance imaging (MRI) when labeled with a paramagnetic tag. Consequently, MRI can be used to image their transport through porous media. In this study, we demonstrated that this method could be applied to image mass transport processes in biofilms. The transport of a complex of gadolinium and diethylenetriamine pentaacetic acid (Gd-DTPA), a commercially available paramagnetic molecule, was imaged both in agar (as a homogeneous test system) and in a phototrophic biofilm. The images collected were T 1 weighted, where T 1 is an MRI property of the biofilm and is dependent on Gd-DTPA concentration. A calibration protocol was applied to convert T 1 parameter maps into concentration maps, thus revealing the spatially resolved concentrations of this tracer at different time intervals. Comparing the data obtained from the agar experiment with data from a one-dimensional diffusion model revealed that transport of Gd-DTPA in agar was purely via diffusion, with a diffusion coefficient of 7.2 × 10−10 m2 s−1. In contrast, comparison of data from the phototrophic biofilm experiment with data from a two-dimensional diffusion model revealed that transport of Gd-DTPA inside the biofilm was by both diffusion and advection, equivalent to a diffusion coefficient of 1.04 × 10−9 m2 s−1. This technology can be used to further explore mass transport processes in biofilms, either by using the wide range of commercially available paramagnetically tagged molecules and nanoparticles or by using bespoke tagged molecules.

scholarly journals Diffusive Plus Convective Mass Transport, Accompanied by Biochemical Reaction, Across Capillary Membrane

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1115
Author(s):  
Endre Nagy ◽  
Imre Hegedüs
Keyword(s):  
Mass Transfer ◽  
Mass Transport ◽  
Membrane Surface ◽  
Mass Transfer Rate ◽  
Kinetic Equations ◽  
Biochemical Reaction ◽  
Variable Parameters ◽  
Transfer Rates ◽  
Operating Modes ◽  
Capillary Membrane

This study theoretically analyzes the mass transport through capillary, asymmetric, biocatalytic membrane reactor, where the diffusive plus convective mass transport is accompanied by biochemical reaction with Michaelis-Menten kinetics. An approach mathematical model was developed that provides the mass transfer properties in closed, explicit mathematical forms. The inlet and outlet mass transfer rates can then put into the differential mass transport expressions of the lumen and the shell fluid phases as boundary values. The approach solution was obtained by dividing the membrane layer into very thin sub-layers with constant transport and reaction kinetic parameters and the obtained second-order differential equation with constant parameters, given for every sublayer, could be solved analytically. Two operating modes are analyzed in this paper, namely, with and without a sweeping phase on the permeating side. These models deviate by the boundary conditions, only, defined them for the outlet membrane surface. The main purpose of this study is to show how the cylindrical space affects the transport process, concentration distribution, mass transfer rates and conversion in presence of a biochemical reaction. It is shown that the capillary transport can significantly be affected by the lumen radius, by the biocatalytic reactor thickness and the convective flow. Decreasing values of the lumen radius reduce the effect of the biochemical/chemical reaction; the increasing reactor thickness also decreases the physical mass transfer rate and, with it, increases the effect of reaction rate. The model can also be applied to reactions with more general kinetic equations with variable parameters.

Heat and Mass Transport in Metal Hydride Based Hydrogen Storage Systems

2009 ◽  
Author(s):  
Daniel E. Dedrick ◽  
Michael P. Kanouff ◽  
Richard S. Larson ◽  
Terry A. Johnson ◽  
Scott W. Jorgensen
Keyword(s):  
Mass Transfer ◽  
Mass Transport ◽  
Hydrogen Storage ◽  
Solid Phase ◽  
Chemical Kinetic ◽  
Transport Processes ◽  
Model Parameters ◽  
Coupled Transport ◽  
Transport Models ◽  
Coupled Transport Processes

Hydrogen storage technologies based on solid-phase materials involve highly coupled transport processes including heat transfer, mass transfer, and chemical kinetics. A full understanding of these processes and their relative impact on system performance is required to enable the design and optimization of efficient systems. This paper examines the coupled transport processes of titanium doped sodium alanates (NaAlH4, Na3AlH6) enhanced with excess aluminum and expanded natural graphite. Through validated modeling and simulation, we have illuminated transport bottlenecks that arise due to mass transfer limitations in scaled-up systems. Individual heat transport, mass transport, and chemical kinetic processes were isolated and experimentally characterized to generate a robust set of model parameters for all relevant operational states. The individual transport models were then coupled to simulate absorption processes associated with rapid refueling of scaled-up systems. Using experimental data for the absorption performance of a 1.6 kg sodium alanate system, comparisons were made to computed results to identify dominant transport mechanisms. The results indicated that channeling around the compacted porous solid can contribute significantly to the overall transport of hydrogen into and out of the system. The application of these transport models is generally applicable to a variety of condensed-phase hydrogen sorption materials and facilitates the design of optimally performing systems.

scholarly journals Theoretical Approach for the Calculation of the Pressure Drop in a Multibranch Horizontal Well with Variable Mass Transfer

ACS Omega ◽  
2020 ◽  
Vol 5 (45) ◽  
pp. 29209-29221
Author(s):  
Ping Yue ◽  
Hongnan Yang ◽  
Chuanjian He ◽  
G. M. Yu ◽  
James J. Sheng ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Theoretical Approach ◽  
Horizontal Well ◽  
Variable Mass

The effect of radiation on free convective flow and mass transfer past a vertical isothermal cone surface with chemical reaction in the presence of a transverse magnetic field

2004 ◽  
Vol 82 (6) ◽  
pp. 447-458 ◽  
Author(s):  
A A Afify
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Boundary Conditions ◽  
Chemical Reaction ◽  
Transverse Magnetic Field ◽  
Convective Flow ◽  
Transverse Magnetic ◽  
Skin Friction Coefficient ◽  
Free Convective Flow ◽  
Cone Surface

The effects of radiation and chemical reactions, in the presence of a transverse magnetic field, on free convective flow and mass transfer of an optically dense viscous, incompressible, and electrically conducting fluid past a vertical isothermal cone surface are investigated. The nonlinear boundary-layer equations with the boundary conditions are transferred by a similarity transformation into a system of nonlinear ordinary differential equations with the appropriate boundary conditions. Furthermore, the similarity equations are solved numerically by using a fourth-order Runge–Kutta scheme with the shooting method. Numerical results for the skin-friction coefficient, the local Nusselt number, the local Sherwood number are given; as well, the velocity, temperature, and concentration profiles are presented for a Prandtl number of 0.7, the chemical-reaction parameter, the order of the reaction, the radiation parameter, the Schmidt number, the magnetic parameter, and the surface temperature parameter. PACS No.: 47.70.Fw

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