Molecular simulation of phenol-containing poly(ether-block-amide) membrane for carbon dioxide separation from nitrogen

Elyasi Kojabad, Mahdi; Moharrami, Mahmoud

Molecular simulation of phenol-containing poly(ether-block-amide) membrane for carbon dioxide separation from nitrogen

Document Type : Original Research

Authors

M. Elyasi Kojabad

M. Moharrami

Department of Chemical Engineering, Faculty of Engineering, Behbahan Khatam Alanbia University of Technology, Behbahan, Iran

Abstract

Research Subject: Carbon dioxide (CO₂) pollution represents a major environmental challenge in contemporary society, primarily driven by industrial expansion. A notable modern approach for CO₂ separation involves the use of polymer membranes, with poly (ether-block-amide) (Pebax) recognized as a prominent industrial membrane in this field. However, this type of membrane is constrained by the permeability–selectivity trade-off, which hinders its broader application in industrial processes. One strategy to overcome this limitation is the incorporation of various functional compounds into Pebax.

Research Approach: This study selected phenol—characterized by its hydroxyl functional group—as a filler, and prepared Pebax membranes with varying phenol concentrations using advanced molecular simulation techniques. Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC) methods were employed to evaluate both the structural properties and gas separation performance of the membranes. Initially, structural properties—including fractional free volume (FFV), density, and polymer chain mobility—were analyzed, followed by assessments of functional properties such as diffusion and solubility coefficients.

Main Results: The incorporation of phenol led to an increase in the membranes' fractional free volume (FFV). Radial distribution function (RDF) analysis revealed that the interaction between CO₂ and phenol molecules was stronger than that between CO₂ and Pebax polymer chains. Furthermore, the results indicated that phenol increased the CO₂ diffusion coefficient by a factor of 5.5 and the solubility coefficient by 1.3 times compared to the pure Pebax membrane, due to Lewis acid–base and π-quadrupolar interactions. Analysis of CO₂ permeability and CO₂/N₂ selectivity in the simulated membranes showed that increasing the phenol content led to higher CO₂ permeability but a continuous decrease in CO₂/N₂ selectivity.

Keywords

Polymer membrane

Molecular simulation

CO2 separation

poly (ether-block-amide)

phenol

Subjects

membrane

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