Abstract
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.
Highlights
Pervaporation is a novel and rapidly developing membrane technology [1,2,3] which is considered effective and low energy consuming compared to other separation methods of near boiling mixtures like the dehydration of organic compounds, the recovery of organic compounds from water, and the separation of organic-organic mixtures
The transport parameters were evaluated based on pervaporation experiments and were compared to the results obtained from transport modelling and fractal analysis
On the basis of the binarized membrane images obtained from the microscope, a fractal analysis concentrating on the fractal dimension DF and generalized fractal dimension Dq were completed
Summary
Pervaporation is a novel and rapidly developing membrane technology [1,2,3] which is considered effective and low energy consuming compared to other separation methods of near boiling mixtures like the dehydration of organic compounds, the recovery of organic compounds from water, and the separation of organic-organic mixtures. The authors studied the experimental data of the hexane/heptane/polyethylene pervaporation system—available in the literature They noted a good agreement between the observed and calculated membrane efficiency in terms of the effects of feed pressure, permeate pressure, and feed concentration. Another alternative model to predict fluxes related to the solution-diffusion has been developed by Klatt In this model, the flux is described as a function of the permeability and the difference in the chemical potential between the feed and the permeate side [13]. Future work is likely to converge on the models based on the molecular simulations Such models could provide information on membrane diffusion and sorption behavior before polymer synthesis [8]. The transport parameters were evaluated based on pervaporation experiments and were compared to the results obtained from transport modelling and fractal analysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
