Hybrid Graphene Oxide/Laponite Layered Membranes with Stable Two-Dimensional Nanochannels for Efficient Separations in Aqueous Environments

A novel type of hybrid graphene oxide/laponite (GO/L) layered membrane is developed with stable two-dimensional (2D) nanochannels for efficient separations in aqueous environments. The electrostatic attractions are generated between the positive charges at the edges of laponite nanosheets and the oxygen-containing groups of GO nanosheets, and such electrostatic attractions between the adjacent GO and laponite nanosheets provide the hybrid GO/L layered membranes strong stability in aqueous environments. When the content of laponite nanosheets in GO/L layered membranes reaches 50 wt %, the GO/L layered membranes are stable enough to be operated in both water and ethanol solutions. Because the hydrophilicity of the hybrid GO/L layered membranes is improved to some extent by the addition of hydrophilic laponite nanosheets, the water permeability of GO-based membranes could be slightly enhanced. Furthermore, because the regularity of the 2D nanochannels of hybrid GO/L layered membranes is not affected by the hybrid regular laponite nanosheets, the separation efficiency of GO-based membranes is high. Demonstrations of efficient separations with the hybrid GO/L layered membranes with 50 wt % laponite nanosheets are carried out for separating basic fuchsine and brilliant yellow dyes from aqueous solutions, and the results show both high permeability and high rejection. The proposed membranes are highly potential for water treatments such as removal of dyes, hormones, and pesticides from aqueous solutions.