Tunable semi-permeability of graphene-based membranes by adjusting reduction degree of laminar graphene oxide layer

Fabrication of Stacked Graphene Oxide Nanosheet Membranes Using Triethanolamine as a Crosslinker and Mild Reducing Agent for Water Treatment

“…We assume that the reason for the missing peaks was due to an enlargement of the interlayer distance because of the severe swelling of the layered structure in water and/or disruption of the alignment of stacked GO layer. This phenomenon has been previously reported [21,22,23,24] and occurs because of the highly hydrophilic functional groups on GO nanosheets. These results clearly indicate that GO-TEOA membranes fabricated with TEOA/GO > 1 retain higher structural stability in water than the unmodified GO membrane, although the peak shifted to a lower angle when compared with dry conditions.…”

“…Improving the structural stability of stacked GO nanosheet membranes to reduce issues such as swelling and disruption of the ordered GO layer is an important issue because negatively-charged GO nanosheets easily delaminate in water due to electrostatic repulsion [21,22,23,24]. Decreased water permeation at high applied pressure due to structural changes has also been reported [3].…”

“…Recent studies have revealed that the stability of GO nanosheet membranes can be improved with a surface reduction treatment of GO and crosslinking between GO layers. Various methods for the reduction treatment of the GO surface such as thermal treatment [25] and chemical reduction using hydrofluoric acid [26] and hydroiodic acid [21] have been reported. However, for the reduced GO (rGO) membranes, water permeation is greatly decreased because the nanochannel size is narrower and the surface hydrophobicity increases.…”

Interlayer Separation in Graphene Paper Comprising Electrochemically Exfoliated Graphene

“…The results of FTIR spectroscopy indicated the presence of oxygen functional groups in the EEG flakes ( Figure 2 c). The characteristic peaks in the FTIR spectrum at 3423, 1635, and 1049 cm −1 corresponded to the hydroxyl, carboxyl, and alkoxy groups, respectively [ 45 , 46 , 47 ]. The chemical structure of the EEG paper was investigated by XPS.…”

Reduced graphene oxide–metal nanoparticle composite membranes for environmental separation and chloro-organic remediation

“…GO membranes are known to partially retain salts owing to the presence of negatively charged carboxylate groups in the conned interlayer spacing. 42 Salt retention by the membranes was evaluated using Na 2 SO 4 , NaCl, MgSO 4, and MgCl 2 for a feed concentration of 7 mM and at a TMP of 7 bar. The corresponding rejections of the four salts by nanocomposite rGO membrane were 55%, 30%, 25%, and 5%, respectively, and by rGO membrane were 56%, 47%, 43%, and 16%, respectively (Fig.…”