Multi-functional membrane based on montmorillonite/graphene oxide nanocomposites with high actuating performance and wastewater purification

The self-standing montmorillonite/graphene oxide (Mt/GO) 2D/2D membranes were prepared by restacking exfoliated layers of montmorillonite (Mt) and graphene oxide (GO) for the multi-applications in the fields of smart actuation and wastewater treatment. Upon asymmetric exposure to humidity, the membrane strips can sense its presence by dramatic bending. The bending angle of membranes up to 50 degrees was detected at 75.3% relative humidity (RH) with proper relative amounts of the two components and the bending angle increased with the increase of RH. Membrane bending was not observed upon exposure to asymmetric ethanol vapor, but detected once exposure to ethanol mist, reaching more than 30 degrees for the sample with low Mt/GO ratios. Additionally, these hybrid membranes displayed a good separation of methylene blue from wastewater using two different treatment methods. Mt membrane had the maximum removal capacity of 280 mg/g using the adsorption method and the hybrid membrane with proper Mt/GO ratios showed the maximum removal of 304 mg/g through filtration technology. Therefore, Mt/GO membranes give rise to the wide potential application including solvent-driven responsive actuators and treatment of industrial wastewater.