Facile fabrication of nanostructured titanium dioxide loaded graphene sheets coated ceramic membrane with superhydrophilic and underwater superoleophobic nature for water treatment

The intrinsic water and oil wettability of hydrophobicity and under-water oleophobicity of graphene, synthesized by ultrasonically exfoliating graphite was reversed to superhydrophilicity and under-water superoleophobicity by ultrasonically compositing it with titanium dioxide (TiO2) nanoparticles. The synthesized TiO2 loaded graphene sheets (TiO2@GS) was spray coated on alumina (Al2O3) ceramic substrate (TiO2@GS-coated Al2O3 ceramic membrane) and used as the filtering medium for the separation of oil-in-water emulsion in water passing dead-end oil water filtration system. The water and oil contact angles of TiO2@GS-coated Al2O3 ceramic membrane in air medium were close to zero in air (θWA = θOA = 0°), and the oil contact under the water (θOW) close to 160 ± 1°. The modified water and oil wettability of TiO2@GS-coated Al2O3 ceramic membrane aided not only to achieve the oil–water separation efficiency as high as 99 %, but also to enhance the workable critical pressure that helps to increase the permeate flux J = 150 L.m−2.h−1. Also, the water passing nature of TiO2@GS-coated Al2O3 ceramic membrane, achieved by the modified surface wettability significantly reduced the oil clogging in the pores of the membrane and thereby increased the recyclability of the filtering membrane for the prolonged use.