Amine-functionalized biogenic silica incorporation effect on poly (ether-block-amide) membrane CO2/N2 separation performance

The development of eco-friendly filler materials in membrane-based gas separation technology have become fascinating science that has established a tremendous circular economy. Biogenic silica (BSi) was recovered from rice husks and functionalized using three different molecular structure amine groups in this study. Poly-ethyleneimine/PEI, N-methylaminopropyl trimethoxysilane/MAPS, and 2-(2-pyridyl) ethyltrimethoxysilane/ PETS are used as inorganic fillers for the fabrication of poly (ether-block-amide) (Pebax-1657) mixed matrix membranes (MMMs). The amine functionalized silica and Pebax chains were found to interact through inter-molecular hydrogen bonding, tightening the interfacial space and strengthening the thermal stability of the original polymeric membranes. Moreover, the amine groups in each functionalized BSi were sufficient to establish a facilitated transport mechanism for CO2 through the Pebax membranes. Amine functionalized BSi could remarkably upgrade the CO2 permeability (110-120%) and CO2/N2 selectivity (60-70%), surpassing Robeson's upper bound 2008. In addition, Pebax/BSi-MAPS-10 became the most reliable membrane in this study, with CO2 permeability of 90.05 Barrer and CO2/N2 selectivity of 100.41. These findings revealed that amine functionalized BSi was promising for the fabrication of high-quality Pebax MMMs for CO2/N2 separation in industrial applications.