Enhanced stability and separation efficiency of graphene oxide membranes in organic solvent nanofiltration

Abstract

GO–BA membranes exhibited excellent nanofiltration performances and long-term stability for OSN with the assistance of BA polymers.

Functionalizing graphene oxide framework membranes with sulfonic acid groups for superior aqueous mixture separation

“…Since the formation of the GO laminar membrane is mainly based on the interlamellar π-π and hydrogen bonding interactions, [18][19] periodically bridging the GO nanosheets by stronger interactions such as covalent bonding to form an interconnected graphene oxide framework (GOF) membrane is a judicious strategy for restraining the swelling and enhancing the stability. [20][21][22][23] Hung and co-workers obtained various diamine crosslinked GOF membranes with d-spacing from 0.93 to 1.09 nm in the wet state whereas that of the control GO membrane increased from 0.85 to 1.31 nm. 14 Sun et al employed thiourea to crosslink GO, resulting in a narrowed 2D nanochannel.…”

2D-dual-spacing channel membranes for high performance organic solvent nanofiltration

“…For the unmodied GO membrane, aer 72 h testing, the integrity was partially destroyed. This may be because GO membranes with highly charged surfaces can be easily re-exfoliated in polar solvents, 28 while GO-Si2 membranes kept the uniform structure (Fig. S19, ESI †).…”

“…A widely adopted solution to enhance the permeance of the lamellar membranes is to intercalate nano-sized spacers into the interlayers, 20 such as copper hydroxide, 6 carbon nanotubes, 25 nanoparticles, 9,26 and organic molecules. 27,28 Recently, covalent cross-linking has proved effective in achieving high stability of GO membranes in organic solvents. 16,28 An expanded interlayer spacing always leads to a considerably enhanced penetrant permeance.…”

“…27,28 Recently, covalent cross-linking has proved effective in achieving high stability of GO membranes in organic solvents. 16,28 An expanded interlayer spacing always leads to a considerably enhanced penetrant permeance. However, in some previous studies, the spacer size, varying from 5 nm to even a hundred nanometers, are always larger than that of the rejected molecules.…”

2D Material Based Advanced Membranes for Separations in Organic Solvents

“…The rapidly emerging 2D materials bring compelling opportunities to extend the application of membranes into organic solvents. [8,11] Compared with conventional polymeric materials, 2D materials can offer various unique advantages as a membrane material: 1) the distinct mono-to few-atoms-thick morphology of 2D nanosheets enable them to serve as desirable building blocks to achieve well-controlled thickness, which can be used to engineer the transport properties of membranes; [12][13][14][15] 2) the interlayer spacing between 2D material nanosheets is well-defined at the nanometric scale with a narrow size distribution, making it possible for achieving specific molecular selectivity; [15][16][17][18] 3) the ability of 2D materials in forming slit-type nanochannels can facilitate molecule transport under nanoscale spatial confinements, which sometimes present unexpected nanofluidic behaviors; [13,14,19] 4) the tunable physicochemical properties and interlayer spacings/nanopores of 2D materials offer greater versatility for membrane designs; [20][21][22] and last but not least 5) some 2D materials also possess outstanding chemical resistances in organic solvents and harsh chemical environments, making membrane fabrication and application possible in a multitude of separation processes. [16,17,23] For example, 2D boron nitride (BN) nanosheets [24,25] possess excellent chemical stability, which enables their utilization as membranes under harsh conditions, such as at high temperatures or in strongly acidic and alkaline media.…”