Abstract

The effect of thickness in multilayer thin-film composite membranes on gas permeation has received little attention to date, and the gas permeances of the organic polymer membranes are believed to increase by membrane thinning. Moreover, the performance of defect-free layers with known gas permeability can be effectively described using the classical resistance in series models to predict both permeance and selectivity of the composite membrane. In this work, we have investigated the Pebax®-MH1657/PDMS double layer membrane as a selective/gutter layer combination that has the potential to achieve sufficient CO2/N2 selectivity and permeance for efficient CO2 and N2 separation. CO2 and N2 transport through membranes with different thicknesses of two layers has been investigated both experimentally and with the utilization of resistance in series models. Model prediction for permeance/selectivity corresponded perfectly with experimental data for the thicker membranes. Surprisingly, a significant decrease from model predictions was observed when the thickness of the polydimethylsiloxane (PDMS) (gutter layer) became relatively small (below 2 µm thickness). Material properties changed at low thicknesses—surface treatments and influence of porous support are discussed as possible reasons for observed deviations.

Highlights

  • Membranes are considered a potentially effective tool for separation of carbon dioxide (CO2 ) from gas mixtures

  • Deionized water (18.3 MΩ cm−1 ) was obtained by reverse osmosis followed by ion exchange and oxide) (PEO) and 40 wt% polyamide-6 (PA6) in its structure was provided by Arkema (Kyoto, Japan) filtration (Millipore, Direct-QTM, Burlington, USA) and used forHexane substrate washing solution in the form of pellets and used as received forMA, membrane preparation

  • The porous support used in this study showed meager resistance to the CO2 and N2 flow

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Summary

Introduction

Membranes are considered a potentially effective tool for separation of carbon dioxide (CO2 ) from gas mixtures. A number of negative were observed in selective the layers oflayers [8] Such ultimate(PDMS, thickness:rubbery accelerated aging, pronounced defect formation, and permeability decrease. Membranes with more complex are aiming polymer) are materials most used as gutter layers in TFCstructures membranes, due to their to overcome these drawbacks In such membranes, the thin selective layer is most often assembled high gas permeability [9]. 40 wt% polyamide-6 in its PA in the structure, Pebax polymers possess excellent mechanical properties while phase-separated is one of the most investigated for selective layer formation in TFC separation membranes for CO2. Layer and PDMS gutter layer (chemical structures are given in Figure 1) transferred onto porous In this current work, we investigate the double layer membrane composed of Pebax-1657 support to selective form a layer composite membrane. Different amounts of polyamide 6 and polyethylene oxide blocks in the structure

Materials
Membrane
Gas Permeation Measurement
Resistance Model for Gas Permeation Description on Three-Layer System
Confirmation
Resistance Model Predictions
Cross Section
Discussion

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