Photocatalytic interlayer spacing adjustment of a graphene oxide/zinc oxide hybrid membrane for efficient water filtration

The intercalation of ZnO nanoparticles into a layer-stacked graphene oxide membrane has a positive impact on its water permeability, physical compaction, and antifouling properties. The interlayer spacing within the GO/ZnO composite membrane is adjustable to a high degree of precision (down to 0.04 Å) by ultra-violet irradiation. This is the smallest controlled reduction of interlayer spacing within a GO membrane ever reported. The photocatalytic reduction of the composite membranes was characterized by their X-ray photoelectron and Raman spectra. The results of the biocidal tests show that the addition of ZnO nanoparticles to a GO membrane inhibits the growth of Escherichia coli B bacteria. The rate of water permeation through the ZnO/GO composite membrane is five times higher than for a pristine GO membrane. The nano-channels in the GO membrane remain locally unchanged after the addition of the ZnO nanoparticles. Thus, the incorporation of the ZnO nanoparticles into the GO membrane has no/little (1% reduction) effect on its Rhodamine B rejection performance. In addition, the presence of ZnO nanoparticles in the nano-channels reduces the extent of membrane compaction, which would decrease the cost of filtration.