Preparation and characterization of modified halloysite nanotubes-Pebax nanocomposite membranes for CO2/CH4 separation

In this study, halloysite nanotubes (HNTs) filler particles were treated in a basic solution with a pH of 11 for their better dispersion during incorporation in Pebax-1657 matrix by 1, 2, 5, 10, 15 wt.% loadings to prepare some HNTs-Pebax nanocomposite membranes. The treated HNTs were evaluated by XRD analysis and the prepared nanocomposite membranes were characterized by DSC, TGA, and FESEM analysis. Treatment of the HNTs in basic solution increased their porosity, pore volume, and specific surface area. CO2 adsorption capacity of the raw and the modified HNTs were measured as 45.7 and 48 mol/kg adsorbent and those of CH4 were evaluated as 34.6 and 32.4 mol/kg adsorbent, respectively. Gas permeation performance of the neat Pebax-1657 and the modified HNTs-Pebax nanocomposite membranes were investigated for CO2/CH4 separation. The 10 wt.% loaded raw HNTs membrane's CO2 permeability and ideal CO2/CH4 selectivity increased to 132.1 Barrer and 18.6 from those for the neat Pebax as 98.4 Barrer and 13.6 while those of 10 wt.% loaded modified HNTs were measured as 144.4 Barrer and 27.2, respectively. The modified HNTs-Pebax nanocomposite membranes' separation performance considerably approached the Robeson upper bound limit of 2008. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

In this study, halloysite nanotubes (HNTs) filler particles were treated in a basic solution to improve dispersion in Pebax matrix, resulting in enhanced gas separation performance of the modified HNTs-Pebax nanocomposite membranes. The CO2 adsorption capacity and gas permeation properties of the membranes were significantly improved compared to neat Pebax membranes, approaching the Robeson upper bound limit for gas separation membranes.