Effect of surface-etched modification on halloysite nanotubes (HNTs) for polysulfone mixed matrix membrane in CO2/CH4 separation

Mixed matrix membranes (MMMs) were fabricated from a 25 wt% of polysulfone (PSf) with halloysite nanotubes (HNTs) selected as the inorganic filler. The incorporation of 1 wt% to 5 wt% of HNTs in the membrane is promising in improving the performance of the membrane for gas separation due to its barrier properties. HNTs was modified by surface-etched method before it is embedded into the membrane in order to reduce the interfacial defects as well as the agglomeration in the membrane. This study further investigated the improvement of the polymer-clay interface interaction, characterize the functional groups, structure and surface area of the newly modified clay and also mechanical properties of the membrane. From the FTIR spectra, it can be seen that the functional group of surface-etched HNTs reduced in intensities compared to the unmodified HNTs. There are no distinct changes in XRD pattern for both unmodified and modified HNTs and tensile strength shows an increment in MMMs embedded with modified clay compared to unmodified clays. The incorporation of surface-etched HNTs was able to improve the membrane properties to a desired membrane that can be applied in the CO2 and CH4 separation

Effect of surface-etched modification on halloysite nanotubes (HNTs) for polysulfone mixed matrix membrane in CO2/CH4 separation

Mixed matrix membranes (MMMs) were fabricated from a 25 wt% of polysulfone (PSf) with halloysite nanotubes (HNTs) selected as the inorganic filler. The incorporation of 1 wt% to 5 wt% of HNTs in the membrane is promising in improving the performance of the membrane for gas separation due to its barrier properties. HNTs was modified by surface-etched method before it is embedded into the membrane in order to reduce the interfacial defects as well as the agglomeration in the membrane. This study further investigated the improvement of the polymer-clay interface interaction, characterize the functional groups, structure and surface area of the newly modified clay and also mechanical properties of the membrane. From the FTIR spectra, it can be seen that the functional group of surface-etched HNTs reduced in intensities compared to the unmodified HNTs. There are no distinct changes in XRD pattern for both unmodified and modified HNTs and tensile strength shows an increment in MMMs embedded with modified clay compared to unmodified clays. The incorporation of surface-etched HNTs was able to improve the membrane properties to a desired membrane that can be applied in the CO2 and CH4 separation

Carbon dioxide/methane separation performance by mixed matrix membrane from polysulfone/ halloysite nanotubes

Gas separation by using membrane-based technology is one of the rising technologies used in the industry. It has many advantages such as low in cost and energy consumption. However, this technology is limited because of the "trade-off" exists between permeability and selectivity of the membrane. Thus, in this study, an inorganic filler, halloysite nanotube is modified with 3-aminopropyl(triethoxysilane) and then incorporated into the polysulfone polymer and the performance of the mixed matrix membranes (MMMs) is investigated. MMMs were analyzed by using SEM, FTIR, tensile and gas permeation tests which studied the morphological differences, mechanical strength, and membrane permeability and selectivity towards CO2 and CH4 respectively. The performance of the MMMs was compared with neat membrane and MMMs with unmodified HNTs. SEM results show an increase of 111% on the thickness of the dense skin layer of MMMs with APTES-modified HNTs compared to the neat membrane and the MMMs with unmodified HNTs. Elongation at break for MMMs with 3-APTES-modified HNTs also increased to 24.22%. The gas separation performance of the MMMs with 3-APTES modified HNTs shows an overall increase of 25.37% in the membrane selectivity compared to MMMs with unmodified HNTs while when coating is done, the selectivity of the MMMs with 3-APTES modified HNTs shows an increase from 0.845 to 10.158 for a pressure of 2 bar showing that coating helps in increasing the selectivity of the membrane