scholarly journals Pore Diffusion Model for the Adsorption of Basic Dyestuffs onto Natural Clay in Batch Adsorbers

1992 ◽  
Vol 9 (2) ◽  
pp. 109-120 ◽  
Author(s):  
Mohammad S. El-Geundi
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Diffusion Model ◽  
Sherwood Number ◽  
Pore Diffusion ◽  
Batch Adsorption ◽  
External Mass Transfer ◽  
Natural Clay ◽  
Pore Diffusion Model ◽  
Best Fit

The adsorption of basic dyestuffs (Basic Blue 69 and Basic Red 22) onto natural clay has been studied using a series of batch adsorption runs. The pore diffusion model (PDM) has been developed based on external mass transfer and pore diffusion to predict the performance of a batch adsorber. A computer program has been developed to generate theoretical Sherwood number-time curves and these results were adjusted to experimental Sherwood number-time curves by means of a ‘best fit’ approach. The variables of initial dye concentration and natural clay mass have been successfully correlated using a single external mass-transfer coefficient, Ks, and a single effective pore diffusion coefficient, Deff. The Ks values are 3.3 × 10−5 and 2.6 × 10−5 m/s for Basic Blue 69 and Basic Red 22, respectively. The Deff values are 7.3 × 10−10 and 9.6 × 10−10 m2/s for Basic Blue 69 and Basic Red 22, respectively.

scholarly journals Homogeneous Surface Diffusion Model for the Adsorption of Basic Dyestuffs onto Natural Clay in Batch Adsorbers

1991 ◽  
Vol 8 (4) ◽  
pp. 217-225 ◽  
Author(s):  
Mohammad S. El-Geundi
Keyword(s):  
Mass Transfer ◽  
Surface Diffusion ◽  
Diffusion Model ◽  
Batch Adsorption ◽  
External Mass Transfer ◽  
Natural Clay ◽  
Homogeneous Surface ◽  
Concentration Time ◽  
Ks Values ◽  
Best Fit

The adsorption of basic dyestuffs (Basic Blue 69 and Basic Red 22) onto natural clay has been studied using a series of batch adsorption runs. The homogeneous surface diffusion model (HSDM) has been developed based on external mass transfer and surface diffusion to explain the concentration–time curves. A computer program has been used to generate theoretical concentration–time curves and these results have been adjusted to the experimental data by means of a ‘best fit’ approach. The HSDM has been successfully used to model the dynamics of the adsorption process for basic dyestuffs onto natural clay. The model predicts a single external mass-transfer coefficient, Ks, and a single surface diffusion coefficient, Ds, with initial dye concentration or natural clay mass. The Ks values are 3.4×10–3 and 2.6×10–3 cm/s for Basic Blue 69 and Basic Red 22, respectively. The Ds values are 2.3×10–8 and 1.9×10–8 cm2/s for Basic Blue 69 and Basic Red 22, respectively.

scholarly journals Application of the Film–Pore Diffusion Model to the Sorption of Phenol onto Activated Carbons Prepared from Peanut Shells

2008 ◽  
Vol 26 (9) ◽  
pp. 651-659 ◽  
Author(s):  
Elio E. Gonzo ◽  
Luis F. Gonzo
Keyword(s):  
Mass Transfer ◽  
Diffusion Model ◽  
Effective Diffusion ◽  
Carbon Particle ◽  
Pore Diffusion ◽  
Peanut Shell ◽  
External Mass Transfer ◽  
Transfer Resistance ◽  
Pore Diffusion Model ◽  
The Difference

In this work, the film–pore diffusion model was applied to the adsorption of phenol onto peanut shell activated carbon in a batch stirred vessel. This two-resistance model was applied to predict the phenol concentration decay curves for different initial phenol concentrations, carbon particle sizes and dosages. The predicted concentration decay curves were compared with the experimental findings. The optimum best-fit values of the external mass-transfer coefficient and effective diffusion coefficients were found by minimizing the difference between the experimental and model-predicted phenol solution concentration. It was found that, under the experimental conditions employed in this study, the influence of the external mass-transfer resistance was low. A single value of the mass transport coefficient, kf, of (4.8 ± 1.3) × 10−3 (cm/s) described the whole range of system conditions. The difference between the corresponding values of the effective diffusivity, Deff, was not statistically significant. Consequently, a constant value of the effective pore diffusivity of (4.1 ± 0.4) × 10−6 (cm2/s) was sufficient to provide an accurate correlation of the decay concentration curve.

scholarly journals Branched-Pore Kinetic Model for Basic Dyestuff Adsorption onto Natural Clay

1992 ◽  
Vol 9 (3) ◽  
pp. 199-211 ◽  
Author(s):  
Mohammad S. El-Geundi
Keyword(s):  
Aqueous Solution ◽  
Mass Transfer ◽  
Kinetic Model ◽  
External Mass Transfer ◽  
Natural Clay ◽  
Main Mass ◽  
Micropore Diffusion ◽  
Concentration Time ◽  
Transfer Parameters ◽  
Best Fit

The adsorption of Basic Blue 69 from aqueous solution onto natural clay has been studied using an agitated batch adsorber. The branched-pore kinetic model (BPKM). based on external mass transfer, macropore diffusion and micropore diffusion, has been used to predict the performance of a batch adsorber. A computer program has been developed to generate theoretical concentration-time curves and these results adjusted to experimental concentration-time curves by a ‘best fit’ approach. A sensitivity analysis has been performed to study the effect of the main mass-transfer parameters, Ks, Ds, Kb and f, on the shape of the concentration decay curves. The variables of initial dye concentration and natural clay mass have been successfully correlated using constant values of the mass-transfer parameters Ks, Ds, Kb and f. The Ks value is (3.7 ± 0.1) × 10−3 cm/s, the Ds value is (2.6 ± 0.1) × 10−8 cm2/s. the Kb value is (1.7 ± 0.1) × 10−7 cm/s and finally the f value is 0.56 ± 0.01. The micropore diffusion terms enable the concentration decay curves to be predicted accurately for a longer period of time than in previous models.

scholarly journals Computational Fluid Dynamics (CFD) Modeling and Simulation of Flow Regulatory Mechanism in Artificial Kidney Using Finite Element Method

Membranes ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 139
Author(s):  
Tuba Yaqoob ◽  
Muhammad Ahsan ◽  
Arshad Hussain ◽  
Iftikhar Ahmad
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Diffusion Model ◽  
Process Parameters ◽  
Clearance Rate ◽  
Pore Diffusion ◽  
Large Size ◽  
Depth Analysis ◽  
Pore Diffusion Model ◽  
Element Method

There is an enormous need in the health welfare sector to manufacture inexpensive dialyzer membranes with minimum dialysis duration. In order to optimize the dialysis cost and time, an in-depth analysis of the effect of dialyzer design and process parameters on toxins (ranging from tiny to large size molecules) clearance rate is required. Mathematical analysis and enhanced computational power of computers can translate the transport phenomena occurring inside the dialyzer while minimizing the development cost. In this paper, the steady-state mass transport in blood and dialysate compartment and across the membrane is investigated with convection-diffusion equations and tortuous pore diffusion model (TPDM), respectively. The two-dimensional, axisymmetric CFD model was simulated by using a solver based on the finite element method (COMSOL Multiphysics 5.4). The effect of design and process parameters is analyzed by solving model equations for varying values of design and process parameters. It is found that by introducing tortuosity in the pore diffusion model, the clearance rate of small size molecules increases, but the clearance rate of large size molecules is reduced. When the fiber aspect ratio (db/L) varies from 900 to 2300, the clearance rate increases 37.71% of its initial value. The results also show that when the pore diameter increases from 10 nm to 20 nm, the clearance rate of urea and glucose also increases by 2.09% and 7.93%, respectively, with tolerated transport of albumin molecules.

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