High-efficiency graphene oxide membranes intercalated by hollow TiO2 nanospheres and CNS@LDH composite spheres for enhancing dye separation from wastewater

Textile wastewater pollution with dyes has become a major source of water pollution. In the study, GO and composite nanospheres (CNS@LDH and HOTiO 2 ) were used to form the composite materials by electrostatic self-assembly method, and the composite materials vacuum filtration on the surface of CA membrane to prepare the composite membranes for dyes separation. Among them, GO was used as a vertical separation layer in dyes separation, while the hollow structure of HOTiO 2 nanosphere with a large specific surface area provided more adsorption sites, and the CNS@LDH nanosphere with core–shell structure played the role of expanding GO sheets and preventing HOTiO 2 from collapsing. Compared with the GO membrane, the water flux of three dyes produced by GO/HOTiO 2 /CNS@LDH composite membrane increased by 18 times with a rejection rate of 99%. In addition, after 10 cycles of experiments, GO/HOTiO 2 /CNS@LDH composite membrane retained a rejection rate of over 98% with the flux of 79 L∙m −2 ∙h −1 ∙bar −1 for MB. GO/HOTiO 2 /CNS@LDH composite membrane retained a stable rejection rate on three dyes under extreme pH and ionic strength conditions. The composite membrane combined the adsorption and isolation effects of GO, HOTiO 2 , and CNS@LDH, which significantly enhanced the separation performance of dye wastewater. Accordingly, the GO/HOTiO 2 /CNS@LDH composite membrane has great potential in practical wastewater treatment.