Preparation and Pb²⁺ Separation Effect from Water of Graphene Oxide/Modified Carbon Nanotube Composite Membrane

The graphene oxide (GO) obtained by a modified Hummers method and the oxidation modified carbon nanotubes (CNT) were mixed with different mass ratios. After ultrasonic dispersion→centrifugalization→vacuum filtration, the GO/modified CNT composite membranes were prepared. The structure, composition and morphology of the composite membranes were analyzed. The effects of the composite membranes on the separation of Pb²⁺ from water were also measured. The results show that the composite membranes showed a laminar structure. The interlayer spacing of GO increased due to the intercalation of modified CNT, which also increased defects of the membrane. When the mass ratio of GO to modified CNT increased from 1:2 to 1:0, the Pb²⁺ rejection rate of the composite membrane increased from 85% to 99% rapidly, while the water permeation decreased from 550×10^-5 L·m^-2·h^-1·Pa^-1 to 35×10^-5 L·m^-2·h^-1·Pa^-1. When the mass ratio of GO to modified CNT was 1:1, the performance of the membrane was relatively good with a Pb²⁺ rejection rate of 99% and water permeation of 518×10^-5 L·m^-2·h^-1·Pa^-1.