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Abstract Thin film nanocomposite (TFN) membranes of polymer of intrinsic microporosity PIM-1 incorporating graphene oxide (GO) nanosheets of different sizes and chemistries are presented. These membranes show an improved separation performance for the recovery of n -butanol from aqueous solutions through pervaporation; an improvement of ca. a third of the value achieved for pristine PIM-1 thin films is obtained for TFN membranes filled with nanometer-sized reduced octyl-functionalized GO. In addition, these nanometer-sized fillers lead to a maximum increase in total flux of approximately 40%. The thickness of the supported films is in the range 1–1.5 µm, and fillers used are micrometer- and nanometer-sized alkyl-functionalized GO nanosheets and their chemically reduced counterparts. As evidenced by a superior overall membrane performance, the interfacial interaction between the filler and the polymer matrix is enhanced for those whose lateral size is in the nanometer range. Moreover, an enhancement in the separation performance and productivity of such membranes is observed for higher operating temperatures and higher contents of n -butanol in the feed. Graphical abstract fx1 Highlights • PIM-1/alkyl-functionalized graphene thin film nanocomposite (TFN) membranes were prepared. • TFN membranes were tested for n-butanol recovery from aqueous solutions via pervaporation. • The addition of nano-sized fillers improved the separation performance of PIM-1 thin film membranes. • Nano-sized fillers enhanced the total flux up to approximately 40%. [ABSTRACT FROM AUTHOR]

Air gap membrane distillation (AGMD) is an emerging desalination technology with the potential to meet the challenge of global water scarcity due to its low cost and high thermal efficiency compared to other processes. However, despite the potential of AGMD, a lack of appropriate membranes limits its commercial application. Therefore, this study was focussed on the fabrication of high flux, robust membranes for the purification of artificial sea water by incorporating graphene oxide functionalized with 3-(aminopropyl)triethoxysilane (APTS) into PVDF polymer solutions. Successful functionalisation of GO with APTS was confirmed with XPS and FTIR. It was shown that the addition of GO and GO-APTS enhanced the permeate flux by 52% and 86%, respectively, compared to pure PVDF. The best performing membrane contained 0.3 wt% GO-APTS (with respect to PVDF) and had a flux of 6.2 LMH (L m −2 h −1 ) whilst maintaining perfect salt rejection (>99.9%). These improvements were attributed to increased surface and bulk porosity, larger mean pore size and hydrophilic interactions owing to the functional groups of GO and GO-APTS. These membranes are evidence of the potential that GO and related materials have as nanocomposite fillers in high performance desalination membranes. [ABSTRACT FROM AUTHOR]

PIM-1-based freestanding mixed matrix membranes (MMMs) and thin film nanocomposites (TFNs) were prepared by incorporating porous silica nanosheets (SN) and exfoliated SN (E-SN) derived from natural vermiculite (Verm) in the PIM-1 polymer matrix. In addition, SN were functionalized by sulfonic acid and amine groups (S-SN and N-SN, respectively) and were also used as fillers for the preparation of MMMs. The gas separation performance was evaluated using CO 2 /CH 4 and CO 2 /N 2 (1:1, v:v) binary gas mixtures. Among freestanding membranes, fresh ones (i.e. tested right after preparation) containing 0.05 wt% functionalized SN and E-SN outperformed the neat PIM-1, surpassing the 2008 Robeson upper bound. At the same filler concentration, fresh MMMs with sulfonic acid-functionalized SN (S-SN) exhibited 40% higher CO 2 permeability, 20% higher CO 2 /N 2 selectivity and almost the same CO 2 /CH 4 selectivity as neat PIM-1 membranes. Moreover, after 150 days of aging, these membranes were capable of maintaining up to 68% of their initial CO 2 permeability (compared to 37% for neat PIM-1). When prepared as TFN membranes, the incorporation of 0.05 wt% of S-SN led to 35% higher initial CO 2 permeance and five times higher CO 2 permeance after 28 days. [Display omitted] • Freestanding and thin PIM-1-based films were fabricated using silica nanosheets (SNs). • The prepared MMMs and TFNs were tested for CO 2 /N 2 and CO 2 /CH 4 separation. • PIM-1/sulfonated SNs (0.05 wt%) showed the best initial performance. • The incorporation of SNs partially prevented aging in both TFNs and MMMs. [ABSTRACT FROM AUTHOR]

To improve the performance and durability of phosphoric acid (PA) doped polybenzimidazole (PBI) membranes in high–temperature proton exchange membrane fuel cells (HT–PEMFCs), in this work, as–received natural muscovite (Mus), a clay material, was successfully incorporated into PBI matrix as an inorganic filler through the doctor blade method. The amount of Mus was varied (0.5–2 wt%) to explore its impact on the proton conductivity, mechanical and dimensional stability, power density, durability, and acid retention ability of the composite membranes. As the incorporation of Mus into membranes can introduce interactions with polymer chains and PA molecules to afford additional proton transport pathways at the interfaces in Mus–PBI and Mus–PA crosslinks, the membrane with 1 wt% Mus showed highest power density of 586 mW cm−2 at 150 °C without humidification, 24% higher than the pure PBI membrane (474 mW cm−2). Meanwhile, the PA doped composite membrane with 1 wt% Mus also displayed the highest mechanical strength (7.5 MPa) and lowest dimensional swelling (70.99% in area swelling and 202% in volume swelling). Compared with the pristine PBI membrane, the composite membranes had significantly improved durability under accelerated stress test (AST). The decreased ohmic resistance and increased polarization resistance after AST are related to the membrane thinning and the loss of catalyst active area, respectively. Most importantly, it was found that the strong interactions between Mus and PA molecules lead to improved acid retention ability of the composite membranes, thus less leached acid from the composite membrane reduces the negative effects on the catalyst degradation to alleviate degradation on cell performance and durability. [Display omitted] • Natural muscovite was successfully incorporated into PBI membranes using the doctor blade method. • The prepared composite membranes show better power density and durability than the pure PBI membrane. • The interactions between Mus and PA explored by EDS, TGA and XPS benefit improved acid retention ability. [ABSTRACT FROM AUTHOR]

Abstract: Composite polymer proton exchange membranes (PEM) were prepared by solution recasting. The composite membranes formed are based on Nafion incorporating a silane functionalized zeolite, mordenite, as an additive. The composite membranes were placed within a single cell DMFC and compared to an MEA featuring a standard Nafion 125μm membrane. The impact of mordenite particle size, the choice of the silane functionalizing agent and the membrane preparation procedure are investigated. A composite ion exchange membrane which featured Nafion and a ground mordenite which was functionalized using glycidoxypropyltrimethoxysilane achieved a power density that outperformed a standard Nafion MEA under all conditions. [Copyright &y& Elsevier]