Interlamination restrictive effect of carbon nanotubes for graphene oxide forward osmosis membrane via layer by layer assembly

Sodium ions will expand the spacing between graphene oxide layers because of the limiting effect, and thus the ordered structure of layer-by-layer membranes via GO disappeared after long running in the sodium ions. GO-OCNTs-LbL membrane was prepared by graphene oxide (GO) and oxidized carbon nanotubes (OCNTs) with 5 bilayers on a polyethersulfone membrane. Insert of OCNTs in the GO interlayer for GO-OCNTs-LbL membrane restricts the expansion of GO. Performance of FO membranes can be investigated by NaCl, MgCl₂, Na₂SO₄, and sucrose as draw solutions and deionized water as feed solution. GO-OCNTs-LbL membrane has a higher water flux than GO-LbL membrane for NaCl, MgCl₂, Na₂SO₄ and sucrose as DS. Solute flux of GO-OCNTs-LbL membrane for NaCl decreased by 70.2% than that of GO-LbL membrane. Therefore, GO-OCNTs-LbL membrane exhibit better rejection performance for NaCl than GO-LbL membrane.