scholarly journals Comparison of Single and Double-Network PVA Pervaporation Performance: Effect of Operating Temperature

2020 ◽  
Vol 64 (3) ◽  
pp. 377-383
Author(s):  
Asmaa Selim ◽  
András József Tóth ◽  
Enikő Haáz ◽  
Dániel Fózer ◽  
Péter Mizsey
Keyword(s):  
Operating Temperature ◽  
Sorption Process ◽  
Ethanol Solution ◽  
Sequential Method ◽  
Ethanol Mixture ◽  
Performance Effect ◽  
Double Network ◽  
Thermal Crosslinking ◽  
High Ethanol ◽  
And Diffusion

Thermal crosslinking sequential method applied for DN-PVAs generation efficiently. The swelling measurements investigated that the hydrophilicity of the membrane decreases because of the collaboration of the second thermal crosslinked PVA matrix. The dehydration performance of ethanol solution showed improved using the thermal crosslinked double network PVA membrane. The pervaporation dehydration of the water-ethanol mixture was investigated at different conditions. The separation selectivity showed a significant improvement, while the permeation flux declines due to the incorporation of the second PVA network under 95 % ethanol and at 40 °C. Increasing the feed temperature enhanced the permeability of the membrane, while decreasing the water content in the feed resulted in an increase in the selectivity. The overall results showed that, at high operating temperature and high ethanol concentration in the feed, the prepared membranes are highly selective towards the water with reasonable fluxes values. The influence of temperature permeation parameter and diffusion coefficient of the feed component is also discussed. The negative heat of sorption ( ∆Hs ) values calculated on the basis of the estimated Arrhenius activation energy values indicates that the sorption process is controlled by Langmuir's mode.

scholarly journals Biosorption and Diffusion Modeling of Pb(II) by Malt Bagasse

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Klaiani B. Fontana ◽  
Giane Gonçalves Lenzi ◽  
Erica R. L. R. Watanabe ◽  
Ervin Kaminski Lenzi ◽  
Juliana A. M. T. Pietrobelli ◽  
...  
Keyword(s):  
Sorption Process ◽  
Isotherm Models ◽  
Diffusion Modeling ◽  
Biosorption Capacity ◽  
Kinetic And Thermodynamic Parameters ◽  
Pseudo Second Order ◽  
Ph Optimization ◽  
Kinetics Of ◽  
And Diffusion

The removal of Pb(II) from water by biosorption processes onto malt bagasse was investigated and the kinetic and thermodynamic parameters were obtained; additionally a diffusion modeling was proposed. The characterization of malt bagasse was performed by FTIR and SEM/EDS. The experiments were conducted in batch system and an experimental design based response surface methodology was applied for agitation speed and pH optimization. The kinetics of biosorption followed pseudo-second-order model and the temperature of the process affected the biosorption capacity. Isotherm models of Langmuir, Freundlich, and Elovich were applied and the Langmuir model showed better fit and the estimated biosorption capacity was 29.1 mg g−1. The negative values obtained for ΔG° and positive values of ΔH° confirm, respectively, the spontaneous and endothermic nature of the process. The diffusion modeling was performed based on experiments in the absence of agitation to investigate the influence of the biosorbent on the sorption process of Pb(II) ions.

scholarly journals Moisture Recovery – A Dynamic Modelling Approach

2019 ◽  
Vol 111 ◽  
pp. 01099
Author(s):  
Martin Kremer ◽  
Paul Mathis ◽  
Dirk Müller
Keyword(s):  
Experimental Data ◽  
Residential Buildings ◽  
Dynamic Modelling ◽  
Sorption Process ◽  
Climatic Conditions ◽  
Energy Saving Potential ◽  
Partial Load ◽  
Fitted Parameter ◽  
And Diffusion ◽  
Ventilation Systems

With rising insulation standards, the use of mechanical ventilation, especially in non-residential buildings, is becoming increasingly relevant. To ensure thermal comfort and avoid health problems for people in the room, cost- and energy-intensive humidification of the supply air is necessary. The use of moisture recovery systems can thus significantly reduce the energy consumption of ventilation systems. Despite this energy-saving potential, moisture recovery systems are rarely used in ventilation systems. To forecast the efficiency of moisture recovery systems in partial load operation and under different climatic conditions, a dynamic model of a membrane-based enthalpy exchanger was developed in the object-oriented modelling language Modelica. The model is based on the solution diffusion model, a quite common approach. In contrast to the models found in the literature, the sorption process is not assumed to be in equilibrium state. Rather, as a first approach the membrane’s permeance, consisting of the solubility and diffusion coefficient, is modelled with a linear dependency on the moisture difference between the two incoming airflows. A parameter fitting has been carried out with experimental data to determine the unknown material parameters. The model containing the fitted parameter set was validated using different experimental data.

SUPERCONTINUUM GENERATION IN SOLID-CORE PHOTONIC CRYSTAL FIBER INFILTRATED WITH WATER-ETHANOL MIXTURE

2020 ◽  
pp. 92-102
Author(s):  
Quang
Keyword(s):  
Photonic Crystal ◽  
Photonic Crystal Fiber ◽  
Numerical Study ◽  
Pump Energy ◽  
Ethanol Solution ◽  
Solid Core ◽  
Ethanol Mixture ◽  
Crystal Fiber ◽  
Dispersion Regime ◽  
Crystal Fibers

In this paper, we report a numerical study of the supercontinuum (SC) generation in solid-core photonic crystal fibers infiltrated with water-ethanol mixtures. A photonic crystal fiber is constructed as borosilicate glass NC21, which consists of 7 rings of air holes infiltrated with water-ethanol mixtures. We also considered numerically the influence of concentration of the ethanol solution on the dispersion of the fundamental mode. SC generation was demonstrated for the fiber long 20 cm with a pump pulse of 200 fs, the coupled energy of 0.5 nJ at the center wavelength of 1064 nm in the normal dispersion regime. The concentration of ethanol infiltrated to the fiber, the pulse of duration and the pump energy are investigated.

scholarly journals Pervaporation Performance of Ag-PVA Nanocomposite Membranes: Effect of Operating Temperature

2019 ◽  
Vol 64 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Asmaa Selim ◽  
András József Tóth ◽  
Enikő Haáz ◽  
Dániel Fózer ◽  
Péter Mizsey
Keyword(s):  
Vinyl Alcohol ◽  
Water Flux ◽  
Sorption Process ◽  
Poly Vinyl Alcohol ◽  
Nanocomposite Membranes ◽  
Azeotropic Point ◽  
Influence Of Temperature On ◽  
And Diffusion

The features of pervaporation are continuously improved with the production of more and more efficient membranes. In our present study, silver nanoparticles are in-situ generated in a poly (vinyl alcohol) using solution-casting in order to enhance its capability for pervaporation. The membrane is tested on the case study of ethanol dehydration by pervaporation. Effect of silver content on the pervaporation separation index and the enrichment factor of the membrane at 15 % mass water at 40 °C are reported. Pervaporation data for nanocomposite membranes show around 100 % increase in the water permeance values while the intrinsic selectivity decreases that is typical for pervaporation membranes. The water permeances of original crosslinked PVA membrane and the 2.5 % silver loaded PVA membrane are 26.65 and 70.45 (g/m2.kPa.h), respectively. The values of total flux are closely related to water flux, showing that membranes could be successfully assigned to separate water from ethanol even at the azeotropic point. The influence of temperature on the efficiency of the pervaporation process, permeation parameter and diffusion coefficient of the feed component is also discussed. The negative heat of sorption (∆Hs) values calculated on the basis of the estimated Arrhenius activation energy values indicates that the sorption process is controlled by Langmuir's mode. Our results show that the 0.5 mass% silver loaded poly (vinyl alcohol) membrane exhibits excellent PV performance.

New Mathematical Model for Determining Time-Dependent Adsorption and Diffusion of Dyes into Fibers through Dye Sorption Curves in Combination Shades

1997 ◽  
Vol 67 (10) ◽  
pp. 701-706 ◽  
Author(s):  
E. Cleve ◽  
E. Bach ◽  
U. Denter ◽  
H. Duffner ◽  
E. Schollmeyer
Keyword(s):  
Mathematical Model ◽  
Dye Adsorption ◽  
Fiber Surface ◽  
Sorption Process ◽  
Time Dependent ◽  
Direct Dyes ◽  
Dyeing Process ◽  
Dye Sorption ◽  
Dyeing Parameters ◽  
And Diffusion

Dye uptake of textile substrates can be described as time-dependent by a new mathematical model, in which the sorption process is divided into fast and slow subprocesses. The fast subprocess describes the adsorption of the dye onto the fiber surface, and the slow one details the diffusion of the dye into the fiber. In addition, dye desorption is simultaneously considered along with adsorption. Relating this concept to the dyeing process, it is possible to divide the process into two parts—dye adsorption and diffusion. The model is verified by dyeing cotton with direct dyes, but the results are also transferable to other fibers and dye classes. Using this model, optimum dyeing parameters and dye combinations can be determined from the sorption curves, which are easily obtained by UV-VIS spectrophotometry.

Simulation Study of the Volume Properties and Diffusion of 1-Butyl-3-Methylimidazolium Tetrafluoroborate/Ethanol Mixture

2015 ◽  
Vol 1095 ◽  
pp. 363-366
Author(s):  
Guo Cai Tian ◽  
Ding Wang
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Molecular Dynamics Simulation ◽  
Mole Fraction ◽  
Simulation Study ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Ethanol Mixture ◽  
Volume Properties ◽  
And Diffusion

The molecular dynamics simulation method is used to study volume properties and diffusion of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4])/ethanol mixture with different molar fractions of ethanol. It is found that the density of the mixture decrease with the increasing of the mole fraction of ethanol, whereas the diffusion coefficient increases. The excess molar volume all appear negative over the entire mole fraction of ethanol which agree well with experimental results.

scholarly journals Thermodynamic properties of the bubble growth process in a pool boiling of water-ethanol mixture two-component system

2019 ◽  
Vol 17 (1) ◽  
pp. 88-95
Author(s):  
Mohammad Sattari ◽  
Leila Mahdavian
Keyword(s):  
Heat Flux ◽  
Bubble Growth ◽  
Mass Fraction ◽  
Bubble Diameter ◽  
Pool Boiling ◽  
Ethanol Solution ◽  
Two Component System ◽  
Steel Cylinder ◽  
Ethanol Mixture ◽  
Two Component

AbstractSaturated pool boiling in a two-component water-ethanol solution was studied at a pressure of one atmosphere in a horizontal stainless steel cylinder. Solutions with volumes of 3%, 7%, and 12% of water-ethanol solution were examined at a heat flux of 1.8 to 60 kW/m2. Videos and photos were analyzed and changes in bubble diameter, growth, and departure parameters were recorded. The results showed that the bubble departure diameters increased with increasing heat flux, but diameters decrease with increasing ethanol mass fraction. The experimental data are evaluated with two models of Alavi Fazel and Hamzehkhani’s model, have better fitting with Hamzehkhani’s model.

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