Homostructured graphene oxide-graphene quantum dots nanocomposite-based membranes with tunable interlayer spacing for the purification of butanol

Abstract

The successful tuning of the GO interlayer space was possible by using OGQDs. The integration of OGQDs was also found to improve the separation efficiency by blocking the transport of alcohol molecules and allows the faster transport of water molecules. • A homostructured selective layer from GO and OGQDs was made. • The GO interlayer space was tuned by using OGQDs. • The separation of butanol/water mixture was augmented by OGQD integration. • The altered transport channels blocked the n -butanol molecules to permeate. The two-dimensional graphene oxide (GO) shares similar structure and functional groups with the zero-dimensional oxygen-passivated graphene quantum dots (OGQDs) but differs in size. Herein, homostructured membranes with GO and OGQDs were prepared through the pressure-assisted self-assembly method. The OGQDs loading were varied to adjust the interlayer spacing between GO nanosheets. The fabricated GO-OGQDs composite membranes were characterized accordingly to identify the interactions between the two carbon-based nanomaterials and its effect on the pervaporative dehydration of n -butanol. A stable nanocomposite lamella was achieved through π-π interactions and hydrogen bonding. The membranes showed an excellent performance in pervaporation of 90/10 wt% n -butanol/water mixture at 25 °C. The pristine GO and GO-OGQD 100 composite membranes resulted in a total flux of 760 gm -2 h −1 and 945 gm -2 h −1 , respectively. At 100 ppm OGQD loading, the composite membrane also resulted with a high-water concentration in permeate of 99.99 wt%. The augmented performance was due to the alteration of the hydrophilic transport channels on GO by OGQD integration. This helped to increase the water flux and blocks the n -butanol molecules to permeate. The GO-OGQD 100 composite membrane provides good performance even in long-term operation. The results herein provide an understanding in preparing nanocomposite materials with similar chemical structures that differ in size. Furthermore, the successful purification of butanol could be done through an environmentally friendly membrane separation process.