Search

Thin membranes (900 nm) were prepared by direct transformation of infiltrated amorphous precursor nanoparticles, impregnated in a graphene oxide (GO) matrix, into hydroxy sodalite (SOD) nanocrystals. The amorphous precursor particles rich in silanols (Si−OH) enhanced the interactions with the GO, thus leading to the formation of highly adhesive and stable SOD/GO membranes via strong bonding. The cross‐linking of SOD nanoparticles with the GO in the membranes promoted both the high gas permeance and enhanced selectivity towards H2 from a mixture containing CO2 and H2O. The SOD/GO membranes are moisture resistance and exhibit steady separation performance (H2 permeance of about 4900 GPU and H2/CO2 selectivity of 56, with no degradation in performance during the test of 50 h) at high temperature (200 °C) under water vapor (4 mol %). [ABSTRACT FROM AUTHOR]

By the combination of the two-dimensional graphene oxide with stable covalent organic frameworks, composite membranes are fabricated through vacuum filtration with the high performance for H 2 /CO 2 separation. • A series of TpPa COFs are synthesized by facile mechanical grinding. • TpPa COFs are fabricated into membranes by the assistance of GO. • The membranes are prepared via a universally applicable vacuum filtration method. • The composite membranes exhibit high performance of H 2 /CO 2 separation. Covalent organic frameworks (COFs) are getting more attention by virtue of their intriguing architectures and properties. However, the obstacle for fabricating sequential COF-based membranes for gas separation has become a challenge. In this research, a series of TpPa COFs are successfully synthesized by a facile approach of mechanical grinding. To alleviate the dilemma of membrane formation, we introduce graphene oxide (GO) that owns two-dimensional flexibility to sufficiently assist the COFs to form lamellar membranes. By directly mixing the solutions of GO and COFs, robust and continue COFs/GO composite membranes are prepared without defects via the vacuum filtration. The thickness and the H 2 /CO 2 selectivity of the membranes can be regulated by increasing the amount of GO. The optimal membrane obtained with a GO/COFs ratio of 33.33% (TpPa-1-30/GO-10) exhibits the H 2 /CO 2 selectivity of 25.57 with H 2 permeance of 1.067 × 10−6 mol·m−2·s−1·Pa−1. This work provides a simple, universal and applicable approach to prepare COF-based composite membranes for separation. [ABSTRACT FROM AUTHOR]

By the combination of graphene oxide with multiple "plug-ins", the composite membranes are fabricated for nanofiltration with high water permeance (82 L m−2h−1 bar−1) and ideal rejection rate (99.98%). [Display omitted] • The GO membranes contain the multiple "plug-ins" of β-CD and TMC. • The composite membranes exhibit high water permeance and ideal dye rejections. • The different effects of "plug-ins" on the nanofiltration performance are studied. The membranes based on graphene oxide (GO) have shown vast perspectives in nanofiltration, while the swelling of GO membranes in water environment poses a critical challenge for practical applications. In this study, we report the simple fabrication of stable GO membranes in water environment through intercalating multiple "plug-ins": the filter of β-cyclodextrin (β-CD) and the crosslinker of trimesoyl chloride (TMC), which can significantly enhance sieving effect and stability of membranes, and efficiently remove dyes and salts. The β-CD possess the cavity range of 6.0–6.5 Å which is larger than the diameter of water molecules, which can introduce extra water passage and hinder the permeation of dye molecules. In addition, the remaining hydroxyl groups on the membrane surface enhance the hydrophilicity, benefiting to enhance water permeance. At the same time, TMC cross-links β-CD and GO nanosheets to reinforce the membrane. The water permeance of the GO/β-CD/TMC membrane reaches 82 L m−2h−1 bar−1, and the dye rejection (crystal violet) is 99.98%. Therefore, GO membranes prepared by the multiple "plug-ins" incorporation strategy are promising candidates for the nanofiltration process to remove dyes. [ABSTRACT FROM AUTHOR]