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Covalent organic framework (COF)-based membranes are burgeoning candidates for separation technologies owing to their well-ordered channel structures. The exponential interest in the stability of the COF membrane on exposure to harsh organic solvents is directed to develop a composite membrane for dye separations in polar aprotic solvents. Here, we reported a nanocomposite membrane composing of a single-walled carbon nanotube (SWCNT)/COF (an imine-based COF) hybrid on a commercial polytetrafluoroethylene (PTFE) substrate, with a thickness of ∼58 nm prepared in a diffusion cell. This membrane displayed high permeability and stability toward nonpolar and aprotic solvents. It exhibited high permeability for lower viscous organic solvents such as hexane (66 L m

Nitrogen containing microporous polymers, DMP-I and DMP-II, were synthesized by a condensation reaction using N , N ′-(1,4-phenylenebis(methanylylidene)) bis(benzene-1,4-diamine) for the selective CO 2 capture. These polymers have moderate surface area and pore size distribution. The prepared polymers are suitable for CO 2 capture because of the higher number of Lewis basic sites. The interactions between the polarized groups and gas molecule increase the CO 2 uptake of 8.7 wt.% at one bar, irrespective of surface area. Furthermore, these polymers exhibit high stability and resistant toward many solvents including water. The breakthrough experiments were carried out to investigate the selectivity potential of the polymers. In addition, the adsorbate-adsorbent interactions are highly reversible and hence these polymers are anticipated to be good sorbent.

Graphene oxide (GO) has been intensively adopted as the building block of separation membranes due to its excellent mechanical strength and atomic scale interlayer spacing. However, the practical application of GO nanosheet-based membranes are limited by the swelling and disintegration of GO membranes in water owing to hydration and electrostatic repulsion. In this work, we firstly fabricated a type of layered double hydroxide (LDH) nanosheets, Co(OH)2 nanosheets, by in-situ growth on the surface of GO nanosheets, followed by coating such GO/Co(OH)2 hybrid nanosheets on a microporous substrate through vacuum suction to form a single-layered GO/Co(OH)2 hybrid thin membrane. The electrostatic and coordination interactions between GO and Co(OH)2 nanosheets are found to stabilize the GO/Co(OH)2 hybrid membrane in water, and the hybrid membrane shows good resistance to shear force in a pressurized crossflow nanofiltration system with crossflow speed as high as 0.5 m s−1. With permeation flux up to 17.0 L m−2 h−1, >91% rejection to inorganic salts like Na2SO4 and >98% rejection to various organic dyes (transmembrane pressure: 6 bar, crossflow speed: 0.27 m s−1), the hybrid membrane also survives the challenges of different pH environments, elevated transmembrane pressure and a 60 h continuous crossflow test. Such significantly improved stability from pure GO membranes is expected to enable the 2D nanomaterial based membranes for practical filtration applications in the water industry.

Azo bridged, heterocyclic, microporous polymers were synthesized by a metal catalyst-free direct one-step coupling reaction of a diazotized amine group with the five-membered ring. The two polymers were synthesized by incorporating pyrrole and imidazole groups. These polymers are amorphous in nature and exhibited surface areas between the range 100–300 m2 g−1. The CO2 adsorption capacity was investigated and it was 3.5 mmol g−1 at 298 K at 1 bar. Meanwhile, the CO2/N2 selectivity of the polymers was measured between 20 and 41 and the interactions of the polymers with gas molecules are discussed.