Biomimetic Superhydrophobic/Superoleophilic Highly Fluorinated Graphene Oxide and ZIF‐8 Composites for Oil–Water Separation

Abstract

Superhydrophobic/superoleophilic composites HFGO@ZIF-8 have been prepared from highly fluorinated graphene oxide (HFGO) and the nanocrystalline zeolite imidazole framework ZIF-8. The structure-directing and coordination-modulating properties of HFGO allow for the selective nucleation of ZIF-8 nanoparticles at the graphene surface oxygen functionalities. This results in localized nucleation and size-controlled ZIF-8 nanocrystals intercalated in between HFGO layers. The composite microstructure features fluoride groups bonded at the graphene. Self-assembly of a unique micro-mesoporous architecture is achieved, where the micropores originate from ZIF-8 nanocrystals, while the functionalized mesopores arise from randomly organized HFGO layers separated by ZIF-8 nanopillars. The hybrid material displays an exceptional high water contact angle of 162° and low oil contact angle of 0° and thus reveals very high sorption selectivity, fast kinetics, and good absorbencies for nonpolar/polar organic solvents and oils from water. Accordingly, Sponge@HFGO@ZIF-8 composites are successfully utilized for oil-water separation.

Shape Controlled Hierarchical Porous Hydrophobic/Oleophilic Metal‐Organic Nanofibrous Gel Composites for Oil Adsorption

“…This well-defined MOF features the Zeolite MTN (MTN = zeolite socony mobilthirty-nine) topology with two types of cavities of small cage 2.5 nm and large cage as 2.9 nm, bearing pentagonal and hexagonal windows ( Figure 1B). [23] Herein, we combined FGO (a structural composition provided in Figures S3a and S4, Supporting Information) with Al-based MOG to yield the composite FGO@MOG. Figure 3A displays nitrogen adsorption-desorption isotherm of the MOG found to be typical type-IV isotherm (H1 type broad hysteresis loop) at higher relative pressure (P/P 0 > 4), exhibiting capillary condensation of nitrogen with in the mesopores.…”

“…[21][22][23][24][25][26][27][28] A great effort has been dedicated to fabricating porous materials with hierarchical porosity with a large specific surface area and being water resistant. Stable hydrophobic MOFs were prepared using hydrophobic functional (F and alkyl) organic linkers or through postsynthetic modification of MOF using hydrophobic groups; although, one cannot rely on many typical MOFs for the oil adsorption due to their microchannels.…”

Imparting amphiphobicity on single-crystalline porous materials

“…Recent studies indicate the observation of framework degradation on the exposure of MOFs to wet CO 2 , even for those claimed with moisture stability3940. To repel water molecules, thereby protecting MOFs against hydrolysis41424344454647484950515253 while preserving crystallinity and intact porosity, some approaches have been developed to impart hydrophobicity/superhydrophobicity on the exterior surfaces of MOFs. For example, Jiang and colleagues54 recently developed a facile yet general coating approach to modify hydrophobic polydimethysiloxane on the surfaces of MOF materials, which exhibited significant enhancement in moisture/water stability.…”

Facile fabrication of superhydrophilic membranes consisted of fibrous tunicate cellulose nanocrystals for highly efficient oil/water separation

“…[8][9][10][11][12][13] Lately, constructing nanomaterial-based filtration membranes have drawn significant attention for oil/water separation, because their high surface area and special surface properties, which are conducive to the liquid flux and rejection rate of membrane productions. [14] However, the advanced performance of nanomaterial-based filtration membranes also accompanied by the high cost of raw materials such as graphene oxide and carbon nanotubes, and complicated preparation process. [15][16][17][18] Therefore, a simple, low cost method to develop filtration membrane with high liquid flux, high rejection, and high cycling performance is critical need.…”