A Simple Methodology to Estimate the Diffusion Coefficient in Pervaporation-Based Purification Experiments

Dudek, Gabriela; Borys, Przemysław

doi:10.3390/polym11020343

Cited by 23 publications

(14 citation statements)

References 36 publications

(45 reference statements)

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“…(5) becomes a linear function of time, as e.g. recently shown (Dudek and Borys 2019;Montelone et al 2018;Bowen et al 2004). From the time lag t = l 2 /6D T , the transport (or Fickian) diffusion coefficient D T can be determined as shown in Eq.…”

Section: The Time Lag Methodsmentioning

confidence: 99%

Diffusion coefficients in nanoporous solids derived from membrane permeation measurements

Caro

2020

Adsorption

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Based on the molecular understanding of the interplay of diffusion and adsorption, new membrane materials can be developed and the operational conditions of gas separation membranes can be optimized. Therefore, numerous diffusion and adsorption studies are conducted to optimize membrane materials. However, in an opposite way, transport or Fickian diffusion coefficients DT can be derived from membrane permeation studies with surprising accuracy. From measuring the gas transport through nanoporous supported thin-layer membranes or through mixed matrix membranes with nanoporous fillers in a polymer matrix, the transport diffusion coefficients DT of gases in novel nanoporous materials such as zeolites, MOFs, COFs… can be estimated.

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Section: The Time Lag Methodsmentioning

confidence: 99%

Diffusion coefficients in nanoporous solids derived from membrane permeation measurements

Caro

2020

Adsorption

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“…The diffusion coefficient was estimated using the method described in [37]. This model assumes that before measurement, the analyzed membranes are not empty.…”

Section: Pervaporation Experimentsmentioning

confidence: 99%

Collation Efficiency of Poly(Vinyl Alcohol) and Alginate Membranes with Iron-Based Magnetic Organic/Inorganic Fillers in Pervaporative Dehydration of Ethanol

2020

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Hybrid poly(vinyl alcohol) and alginate membranes were investigated in the process of ethanol dehydration by pervaporation. As a filler, three types of particles containing iron element, i.e., hematite, magnetite, and iron(III) acetyloacetonate were used. The parameters describing transport properties and effectiveness of investigated membranes were evaluated. Additionally, the physico-chemical properties of the resulting membranes were studied. The influence of polymer matrix, choice of iron particles and their content in terms of effectiveness of membranes in the process of ethanol dehydration were considered. The results showed that hybrid alginate membranes were characterized by a better separation factor, while poly(vinyl alcohol) membranes by a better flux. The best parameters were obtained for membranes filled with 7 wt% of iron(III) acetyloacetonate. The separation factor and pervaporative separation index were equal to 19.69 and 15,998 g⋅m−2⋅h−1 for alginate membrane and 11.75 and 14,878 g⋅m−2⋅h−1 for poly(vinyl alcohol) membrane, respectively.

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“…where m i was the weight of component i in the permeate, A was the effective membrane area, and t was the permeation time to collect m i . The diffusion coefficient was estimated using a previously described method [27]. This model takes into consideration the fact that the analyzed membranes are not empty before the measurement.…”

Section: Pervaporation (Pv) Experimentsmentioning

confidence: 99%

Characterization of the Structure and Transport Properties of Alginate/Chitosan Microparticle Membranes Utilized in the Pervaporative Dehydration of Ethanol

et al. 2020

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The structure and transport properties of alginate/chitosan microparticle membranes used in ethanol dehydration processes were investigated. The membranes were characterized based on images obtained from high-resolution microscopy. The following parameters were determined: the observed total amount of void space, the average size of the void domains, their length and diameter, the fractal dimension, and the generalized stochastic fractal parameters. The total amount of void space was determined to be between 54% and 64%. The average size of the void domains is smaller for alginate membranes containing neat (CS) and phosphorylated (CS-P) chitosan particles when compared to those membranes filled with glycidol-modified (CS-G) and glutaraldehyde crosslinked (CS-GA) chitosan particles. Furthermore, the transport of ethanol and water particles through the studied membranes was modelled using a random walk framework. It was observed that the results from the theoretical and experimental studies are directly correlated. The smallest values of water to ethanol diffusion coefficient ratios (i.e., 14) were obtained for Alg (sodium alginate) membranes loaded with the CS and CS-P particles, respectively. Significantly larger values (27 and 19) were noted for membranes filled with CS-G and CS-GA particles, respectively. The simulation results show that the size of channels which develop in the alginate matrix is less suited for ethanol molecules compared to water molecules because of their larger size. Such a situation facilitates the separation of water from ethanol. The comparison of the structural analysis of the membranes and random walk simulations allows one to understand the factors that influence the transport phenomena, in the studied membranes, and comment on the effect of the length, diameter, number of channels, and variations in the pore diameters on these transport parameters.Polymers 2020, 12, 411 2 of 17 Current research in the pervaporation field is focused on the development of new membrane materials and optimization of the pervaporation process parameters. To advance in both areas, it is necessary to characterize the membrane structure and understand the mass transport processes that are involved in the pervaporation process. One of the methods to study the structure and morphology of the membranes is the fractal analysis. Using the fractal dimension D F and the generalized fractal dimension Dq, it is possible to quantify the structure and morphology of self-similar objects. In our previous work [7], we have shown that there is a strong relationship between the degree of multifractality ∆D and the separation efficiency. Comparing the trends in the changes of the Pervaporation Separation Index (PSI) and the corresponding ∆D values, we have noted, that the maximum PSI was always reached for the lowest values of ∆D. The lower value of ∆D is related to a more homogeneous and self-similar membrane structure. In order to predict the membrane's performance and to design membranes for specific applications, a funda...

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A Simple Methodology to Estimate the Diffusion Coefficient in Pervaporation-Based Purification Experiments

Cited by 23 publications

References 36 publications

Diffusion coefficients in nanoporous solids derived from membrane permeation measurements

Diffusion coefficients in nanoporous solids derived from membrane permeation measurements

Collation Efficiency of Poly(Vinyl Alcohol) and Alginate Membranes with Iron-Based Magnetic Organic/Inorganic Fillers in Pervaporative Dehydration of Ethanol

Characterization of the Structure and Transport Properties of Alginate/Chitosan Microparticle Membranes Utilized in the Pervaporative Dehydration of Ethanol

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