Electric-field-assisted formation of cellulose triacetate/edge-oxidized graphene oxide mixed-matrix membranes for pervaporation desalination

Pervaporation (PV) can be used for the desalination of high-salinity water. However, it is mainly limited by low water fluxes. In this study, mixed-matrix membranes were prepared using cellulose triacetate as the polymer matrix material and edge-oxidized graphene oxide (EOGO) nanosheets as the nanofiller. An external electric field was applied during the membrane solidification process to induce EOGO nanosheets to align along the membrane thickness, shortening the mass transfer pathway of water molecules across the membrane and increasing the water flux. The effects of nanosheet parameters (type and concentration), electric field parameters (strength, frequency, and action time), and solution parameters (solvent type and polymer concentration) on the orientation of nanosheets in dispersions were systematically studied. The membrane properties were characterized to confirm that the electric-field-induced orientation of EOGO nanosheets was fixed in the membrane during the membrane solidification process. At an EOGO concentration of 0.15 wt%, compared with the membrane prepared without the electric field, the membrane prepared under an electric field (47 V/mm and 1000 Hz) exhibited a 22.3% increase in the water flux and maintained the same salt rejection when the PV desalination process had a salt concentration in the feed of 3.5 wt% and a feed temperature of 50 degrees C.

Automated summary

Pervaporation can be improved by using edge-oxidized graphene oxide as a nanofiller. By applying an external electric field during the membrane solidification process, the orientation of nanosheets can be adjusted, leading to increased water flux.