scholarly journals Studies of Adsorption of Heavy Metals onto Spent Coffee Ground: Equilibrium, Regeneration, and Dynamic Performance in a Fixed-Bed Column

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
N. E. Davila-Guzman ◽  
F. J. Cerino-Córdova ◽  
M. Loredo-Cancino ◽  
J. R. Rangel-Mendez ◽  
R. Gómez-González ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Mass Transfer ◽  
Ion Exchange ◽  
Axial Dispersion ◽  
Model Parameters ◽  
Dynamic Adsorption ◽  
Transfer Model ◽  
Transfer Resistance ◽  
Spent Coffee Ground ◽  
Coffee Ground

Equilibrium and dynamic adsorption of heavy metals onto spent coffee ground (SCG) were studied. The equilibrium adsorption of Cd2+, Cu2+, and Pb2+in a batch system was modeled by an ion-exchange model (IEM) based on an ion-exchange of heavy metals with calcium and protons bonded to active sites on SCG surface. The maximum amount of adsorbed metal ions obtained using the IEM was 0.12, 0.21, and 0.32 mmol/g of Cd2+, Cu2+, and Pb2+, respectively. Regeneration of SCG was evaluated using citric acid, calcium chloride, and nitric acid. The observed trend of desorption efficiency through four adsorption-desorption cycles was HNO3> CaCl2> C6H8O7. The effect of process variables such as flow rate and bed height during the dynamic adsorption was evaluated. Moreover, the applicability of a mass transfer model based on external mass transfer resistance, axial dispersion, and ion-exchange isotherm was evaluated, and the results were in good agreement with the experimental data for the adsorption in SCG packed column. The sensitivity analysis of the model parameters showed that axial dispersion coefficient is the most significant parameter in the dynamic simulation. The results obtained showed the potential of SCG as a low-cost material for wastewater metal removal in continuous systems.

scholarly journals Modeling of the adsorption kinetics of zinc onto granular activated carbon and natural zeolite

2006 ◽  
Vol 71 (8-9) ◽  
pp. 957-967 ◽  
Author(s):  
Ljiljana Markovska ◽  
Vera Meshko ◽  
Mirko Marinkovski
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Simulation Study ◽  
Natural Zeolite ◽  
Granular Activated Carbon ◽  
Model Parameters ◽  
Mass Transfer Resistance ◽  
External Mass Transfer ◽  
Transfer Resistance ◽  
Kinetics Of

The isotherms and kinetics of zinc adsorption from aqueous solution onto granular activated carbon (GAC) and natural zeolite were studied using an agitated batch adsorber. The maximum adsorption capacities of GAC and natural zeolite towards zinc(II) from Langmuir adsorption isotherms were determined using experimental adsorption equilibrium data. The homogeneous solid diffusion model (HSD-model) combined with external mass transfer resistance was applied to fit the experimental kinetic data. The kinetics simulation study was performed using a computer program based on the proposed mathematical model and developed using gPROMS. As the two-mass transfer resistance approach was applied, two model parameters were fitted during the simulation study. External mass transfer and solid phase diffusion coefficients were obtained to predict the kinetic curves for varying initial Zn(II) concentration at constant agitation speed and constant adsorbent mass. For any particular Zn(II) - adsorbent system, k f was constant, except for the lowest initial concentration, while D s was found to increase with increasing initial Zn(II) concentration.

scholarly journals Highly Saline Water Desalination Using Direct Contact Membrane Distillation (DCMD): Experimental and Simulation Study

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1575 ◽  
Author(s):  
Noor A. Mohammad Ameen ◽  
Salah S. Ibrahim ◽  
Qusay F. Alsalhy ◽  
Alberto Figoli
Keyword(s):  
Mass Transfer ◽  
Direct Contact ◽  
Saline Water ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Water Desalination ◽  
System Of Nonlinear Equations ◽  
Transfer Model ◽  
Transfer Resistance ◽  
Direct Contact Membrane Distillation

The path for water molecules transported across a membrane in real porous membranes has been considered to be a constant factor in the membrane distillation (MD) process (i.e., constant tortuosity); as such, its effect on membrane performance at various operating conditions has been ignored by researchers. Therefore, a simultaneous heat and mass transfer model throughout the direct contact membrane distillation (DCMD) module was developed in this study by taking into account the hypothetical path across the membrane as a variable factor within the operating conditions because it exhibits the changes to the mass transfer resistance across the membrane under the DCMD run. The DCMD process was described by the developed model using a system of nonlinear equations and solved numerically by MATLAB software. The performance of the poly-tetra-fluoroethylene (PTFE) membrane was examined to treat 200 g/L NaCl saline at various operating conditions. The simulation results in the present work showed that the hypothetical proposed path across the membrane has a variable value and was affected by changing the feed temperature and feed concentration. The results estimated by the developed model showed an excellent conformity with the experimental results. The salt rejection remained high (greater than 99.9%) in all cases. The temperature polarization coefficient for the DCMD ranged between 0.88 and 0.967, and the gain output ratio (GOR) was 0.893. The maximum thermal efficiency of the system was 84.5%.

Effect of temperature on the equilibrium and kinetics of galactose, glucose, and lactose adsorption on a cation exchanger

2014 ◽  
Vol 68 (12) ◽  
Author(s):  
Łukasz Wiśniewski ◽  
Katarína Vaňková ◽  
Pavel Ačai ◽  
Milan Polakovič
Keyword(s):  
Mass Transfer ◽  
Cation Exchanger ◽  
Enzymatic Reaction ◽  
Breakthrough Curves ◽  
Axial Dispersion ◽  
Effect Of Temperature ◽  
Transfer Resistance ◽  
Adsorption Equilibria ◽  
Intraparticle Mass Transfer ◽  
Kinetics Of

AbstractGalacto-oligosaccharides are typically produced by an enzymatic reaction when the post-reaction mixture contains considerable amounts of lactose and glucose and a smaller amount of galactose. In order to develop a process of chromatographic removal of saccharide impurities, adsorption equilibria and kinetics of these di- and monosaccharides were investigated for Diaion UBK 530, an industrialgrade strong cation-exchanger in the Na+ form. Frontal chromatographic experiments were carried out in the temperature range of 30–70°C and a broad interval of saccharide concentrations up to 350 g L−1. Breakthrough curves were described using the equilibrium-dispersive model with the linear adsorption isotherm. Both the distribution and the axial dispersion coefficient values depended on the saccharide molecule type and size. No significant effect of temperature or concentration on the distribution coefficient was observed. The apparent dispersion coefficients of all saccharides exhibited some decrease with the temperature, which was caused by the decrease of the intraparticle mass transfer resistance. An analysis showed that both the intraparticle mass transfer and the axial dispersion had a significant influence on the front dispersion.

A mass transfer model for the fixed-bed adsorption of ferulic acid onto a polymeric resin: axial dispersion and intraparticle diffusion

2016 ◽  
Vol 37 (15) ◽  
pp. 1914-1922 ◽  
Author(s):  
Nancy E. Davila-Guzman ◽  
Felipe J. Cerino-Córdova ◽  
Eduardo Soto-Regalado ◽  
Margarita Loredo-Cancino ◽  
José A. Loredo-Medrano ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Ferulic Acid ◽  
Fixed Bed ◽  
Intraparticle Diffusion ◽  
Axial Dispersion ◽  
Transfer Model ◽  
Mass Transfer Model ◽  
Polymeric Resin ◽  
Fixed Bed Adsorption

Vapor phase transport of AlN in an RF heated reactor: Low and high temperature studies

2003 ◽  
Vol 798 ◽  
Author(s):  
V. Noveski ◽  
R. Schlesser ◽  
J. Freitas ◽  
S. Mahajan ◽  
S. Beaudoin ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Growth Rate ◽  
Vapor Phase ◽  
Near Band Edge ◽  
Model Parameters ◽  
Transfer Model ◽  
Band Edge Emission ◽  
Low Oxygen ◽  
Vapor Phase Transport ◽  
Continuous Growth

ABSTRACTAlN crystals were grown from the vapor phase in an RF heated AlN sublimation reactor. The studies were performed with the following goals: 1) to optimize the growth rate by investigating mass transfer effects, and 2) to establish a process for epitaxial growth on AlN seeds. A one-dimensional mass transfer model based on equilibrium sublimation and gas-phase diffusion was developed. Model parameters were estimated and the model was validated from growth experiments carried out in a 600 Torr nitrogen atmosphere and temperatures ranging from 2000 to 2400°C. Continuous growth on AlN seed crystals was accomplished as a result of optimizing the initial stage of growth and achieving a delicate balance between the rate of mass transfer and the rate of surface rearrangement. During this experimental study, centimeter-size single crystals of AlN were obtained within the 1.25” diameter boule that was grown at a predicted growth rate of 0.1–0.3 mm/hr, at 500 Torr of nitrogen, short source-to-seed distance, low supersaturation and growth temperatures of 2110–2140°C. Chemical analysis of impurities in the grown AlN boules confirmed a very low oxygen contamination of 100 ppm wt. Cathodoluminescence studies showed well defined near band edge emission peak located slightly above 6 eV.

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