Membranes

18 pages, 5348 KiB

Open AccessArticle

Simulating the Permeation of Toxic Chemicals through Barrier Materials

by Alex Bicket, Vivian Lau and Jules Thibault

Membranes 2024, 14(9), 183; https://doi.org/10.3390/membranes14090183 (registering DOI) - 24 Aug 2024

Chemical warfare agents that are liquids with low vapor pressure pose a contact hazard to anyone who encounters them. Personal protective equipment (PPE) is utilized to ensure safe interaction with these agents. A commonly used method to characterize the permeability of PPE towards chemical weapons is to apply droplets of the liquid agent to the surface of the material and measure for chemical breakthrough. However, this method could produce errors in the estimated values of the transport properties. In this paper, we solved numerically the three-dimensional cylindrical Fick’s second law of diffusion for a liquid permeating through a non-porous rubbery membrane to determine the time the permeating species will emerge on the other side of the polymer membrane. Simulations of different amounts of surface area coverage and the geometries of permeate on the membrane surface indicated that incomplete surface area coverage affects the estimation of the transport properties, making the experimentally determined transport properties unsuitable for predictive use. We simulated different permeation values to determine the factors that most influenced the estimation error and if the error was consistent over different permeate–membrane combinations. Finally, a method to correct the experimentally determined permeability is suggested. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

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13 pages, 806 KiB

Open AccessArticle

New Insights on Y, La, Nd, and Sm Extraction with Bifunctional Ionic Liquid Cyphos IL 104 Incorporated in a Polymer Inclusion Membrane

by Mohamed Malki, Lynda Mitiche, Amar Sahmoune and Clàudia Fontàs

Membranes 2024, 14(9), 182; https://doi.org/10.3390/membranes14090182 - 23 Aug 2024

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Abstract

In this study, an ionic liquid-based polymer inclusion membrane (IL-PIM) made of (50% polymer-50% CyphosIL104) was used to extract and separate the rare earth elements (REEs) Y, La, Nd, and Sm in chloride solutions. The effect of extraction time and pH was studied to optimize the extraction and separation conditions. The four REEs were effectively extracted at pH 4–5 from both single and mixed metals solutions. However, at pH 2, only Y was extracted. The recovery of the extracted REEs from the loaded PIM was achieved using HNO₃ and H₂SO₄. In the case of La, it was quantitatively back-extracted with H₂SO₄ after a contact time of 1 h, while up to 4 h was necessary to recover 70% of the extracted Y, Sm, and Nd. Extraction isotherms were studied, and the Freundlich isotherm model was the most adequate to describe the interaction between the PIM and the REEs. Finally, the developed PIM was investigated for the extraction of REEs from mixtures containing other metals, which showed great selectivity for the REEs. Full article

(This article belongs to the Section Membrane Applications for Other Areas)

18 pages, 2713 KiB

Open AccessArticle

Engineering Phosphatidylserine Containing Asymmetric Giant Unilamellar Vesicles

by Jake McDonough, Trevor A. Paratore, Hannah M. Ketelhohn, Bella C. DeCilio, Alonzo H. Ross and Arne Gericke

Membranes 2024, 14(9), 181; https://doi.org/10.3390/membranes14090181 - 23 Aug 2024

Viewed by 186

Abstract

The plasma membrane lipid distribution is asymmetric, with several anionic lipid species located in its inner leaflet. Among these, phosphatidylserine (PS) plays a crucial role in various important physiological functions. Over the last decade several methods have been developed that allow for the fabrication of large or giant unilamellar vesicles (GUVs) with an asymmetric lipid composition. Investigating the physicochemical properties of PS in such asymmetric lipid bilayers and studying its interactions with proteins necessitates the reliable fabrication of asymmetric GUVs (aGUVs) with a high degree of asymmetry that exhibit PS in the outer leaflet so that the interaction with peptides and proteins can be studied. Despite progress, achieving aGUVs with well-defined PS asymmetry remains challenging. Recently, a Ca²⁺-initiated hemifusion method has been introduced, utilizing the fusion of symmetric GUVs (sGUVs) with a supported lipid bilayer (SLB) for the fabrication of aGUVs. We extend this approach to create aGUVs with PS in the outer bilayer leaflet. Comparing the degree of asymmetry between aGUVs obtained via Ca²⁺ or Mg²⁺ initiated hemifusion of a phosphatidylcholine (PC) sGUVwith a PC/PS-supported lipid bilayer, we observe for both bivalent cations a significant number of aGUVs with near-complete asymmetry. The degree of asymmetry distribution is narrower for physiological salt conditions than at lower ionic strengths. While Ca²⁺ clusters PS in the SLB, macroscopic domain formation is absent in the presence of Mg²⁺. However, the clustering of PS upon the addition of Ca²⁺ is apparently too slow to have a negative effect on the quality of the obtained aGUVs. We introduce a data filtering method to select aGUVs that are best suited for further investigation. Full article

(This article belongs to the Special Issue Advances in Symmetric and Asymmetric Lipid Membranes)

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Membranes, Volume 14, Issue 9 (September 2024) – 3 articles

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