Sol–gel fabrication of a non-laminated graphene oxide membrane for oil/water separation

Abstract

A non-laminated graphene oxide membrane with superhydrophilic and underwater superoleophobic properties was fabricated by sol-gel process for effective oil/water separation. † Electronic Supplementary Information (ESI) available: Porosity calculation, separation apparatus, high magnification top view SEM images of LGM, sliding angle measurement of 1,2-dichloroethane (DCE) droplets on the NLGM in water, separation results for other emulsion systems, SEM images of the NLGM after oil/water emulsion separation performance test, photograph of an underwater oil droplet on the NLGM and simulated underwater drag deformation force tests after oil/water emulsion separation test and element component percentages of GO and the NLGM, and. See A non-laminated graphene oxide membrane crosslinked by polyethyleneimine was prepared via a one-step sol-gel process. In the as-prepared membrane, the GO nanosheets remain disordered as in the sol state to form a randomly arranged GO assembly structure, which results in a much higher flux compared with the general laminated GO membrane prepared via vacuum filtration or spin coating because of the lower flow resistance. Further, this random assembly of GO nanosheets give rise to a hierarchical micro/nanoscale rough structure on the membrane surface. Along with the crosslinking reaction, PEI was grafted onto the GO nanosheets to make them hydrophilic. Combining the hydrophilic surface chemistry with the micro/nanoscale hierarchical surface structure, the non-laminated GO membrane exhibited the desired superhydrophilic and underwater superoleophobic properties. We have tested the membrane to separate a series of surfactant-free and surfactant-stabilized oil-in-water emulsions. A high separation efficiency (>99%) and flux were achieved using only gravity without any extra power, much larger than commerical filtration membranes with similar permeation properties. Moreover, the membrane shows an outstanding antifouling performance for oil droplets and can be recycled easily for long-term use.

Cation-diffusion controlled formation of thin graphene oxide composite membranes for efficient ethanol dehydration

“…Particularly for liquid separation processes like nanofiltration [31] and pervaporation [32], the structural stability of GO membranes is essential for molecular separation as GO may disintegrate when adsorbing excessive solvent molecules [33,34], and this situation may get worse for the liquid with a high flow rate promoting turbulence across the membrane surface to reduce con-centration polarization. The common interactions introduced in GO-based membranes are electrostatic attraction [30,35,36], amino-group involved covalent bonding [37,38] and π-π stacking [39][40][41][42], which are typically sourced from polyelectrolytes, diamine and carbon nanotubes, respectively. By virtue of these modified membrane structures, GO laminates have capability to sustain the high performance during the liquid-related separation process.…”

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

“…[16] Considering the aforementioned wettability of TCNC membranes, three types of emulsions including oil-in-water microemulsions, water-in-oil emulsions, and oil-in-water nanoemulsions were prepared to test the universality of TCNC membranes in oil/water emulsion separation. Fig.…”

“…[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.…”

Branched polyethylenimine‐polyethylene glycol‐β‐cyclodextrin polymers for efficient removal of bisphenol A and copper from wastewater

“…The thermal behavior of X-CD_3.9_0.78 was also studied using TGA and DSC. [35][36][37] Figure 4(b) indicates that X-CD_3.9_0.78 is a material with glass transitions below room temperature, such that it has an elastomeric behavior and an amorphous nature suitable for the adsorption process. The weight losses below 250 C were caused by the elimination of the physically adsorbed water from X-CD_3.9_0.78.…”