Mixed matrix membrane incorporated with large pore size halloysite nanotubes (HNT) as filler for gas separation: Experimental

This study investigated the gas separation and transport properties of asymmetric mixed matrix membranes (MMM) fabricated from polyetherimide (PEI); Ultem 1000 incorporated with raw and modified halloysite nanotubes (HNT) as filler. The modified HNTs; S-HNTs were prepared by treating HNTs with N-β-(aminoethyl)-γ-aminopropyltrimethoxy silane (AEAPTMS). FESEM, XRD, FTIR, TGA, DSC and pure gas permeation testing were used to characterise the S-HNTs and the fabricated MMMs. In the first part of the experiments, the effect of dope preparation factors such as: ultrasonic sonication period, filler wetting period and priming period were investigated. In the second part, the influence of silane concentration on the fabricated MMMs was studied. Results showed that, increasing the silane concentration, led to higher tendency in HNT agglomeration which resulted in poor separation properties but permeability enhancement. In the last part, the effect of S-HNTs loading was experienced. Our observations showed that the dispersion of nanoparticles decreased with an increase in the S-HNTs loading. Accordingly, 0.5% loading of silylated-HNT yielded the optimum MMMs in terms of permeability (27% increase) and selectivity (8% increase).

Graphical abstractA perfect compatibility between the polymer and silylated HNTs was observed. A 0.5% loading of silylated-HNTs resulted in 27% enhancement in CO2 permeability and 8% increase in CO2/CH4 selectivity.Figure optionsDownload full-size imageDownload high-quality image (38 K)Download as PowerPoint slideHighlights► Employing halloysite nano tubes (HNTs) as filler to fabricate MMMs. ► Unmodified and modified HNTs have dramatic influences on the fabricated MMMs. ► HNTs are able to be applied to increase both permeability and selectivity of the resultant membranes.