One-step preparation of sepiolite/graphene oxide membrane for multifunctional oil-in-water emulsions separation

Herein, by vacuum-filtered an aqueous sepiolite/graphene oxide (Sep/GO) dispersion on polyvinylidene fluoride (PVDF) microfiltration membrane, and embedded the Sep nanofibers between adjacent GO nanosheets to expand the mass transfer channel and create hierarchical nanostructures on the membrane surface. Accordingly, the pure water flux increased from 7.2 L m−2 h−1 bar−1 of the GO membrane to 531.75 L m−2 h−1 bar−1 of the Sep/GO membrane, which was greatly improved. Sep/GO membranes are effective in separating oil-in-water emulsions because of their good oil/water selectivity and low oil adhesion, with high separation efficiency and relatively high flux. In addition, the membrane maintains underwater superoleophobicity and superior stability in harsh environments. It is worth mentioning that Sep/GO membrane can also separate dyes (methylene blue, Congo red) and some heavy metal ions (Fe3+, Cu2+) from aqueous solution to achieve multifunctional water treatment. Sep/GO membrane is not difficult to fabricate and has broad prospects for multifunctional wastewater treatment. •Sep/GO membrane is simple to prepare and is suitable for mass production.•Prepared membrane can remove various surfactant-stable oil-in-water emulsions.•Certain heavy metal ions and some dyes can also be rejected by prepared membrane.•Sep/GO membrane still maintains good stability in harsh environments.•Sep/GO membrane has low oil adhesion and can be reused after a simple rinse.