Effective separation of surfactant-stabilized crude oil-in-water emulsions by waste brick powders-coated membrane under corrosive conditions

Crude oil spill accidents have occurred frequently, not only seriously destroying the marine ecological environment and threatening human health for a long time, but also generating a great loss of precious resources. Therefore, the treatment of crude oil wastewater, especially under corrosive conditions, is one of the most urgent problems. However, to the best of our knowledge, the effective separation of surfactant-stabilized micro-nanoscale crude oil-in-water emulsions under corrosive conditions have been few reported. Herein, waste bricks are employed to effectively separate the surfactant-stabilized micro-nanoscale crude oil-in-water emulsions under corrosive conditions, which not only realizes the removal of crude oil, but also reduces environmental pollution. The suspensions of waste brick powders (WBP) and sodium alginate were coated onto polyvinylidene fluoride (PVDF) membrane via vacuum-filtration approach to prepare WBP-coated membrane. The as-prepared WBP-coated membrane exhibited excellent underwater superoleophobicity including corrosive conditions and low adhesion to crude oil. Besides, the WBP-coated membrane can separate crude oil-in-water emulsions with separation efficiencies up to 99.8 % and permeating flux as high as 623 L m-2 h-1. More significantly, the as-prepared WBP-coated membrane can successfully separate crude oil-in-water emulsions in the corrosive aqueous (1 M HCl, 1 M NaOH and 3.5 % wt NaCl solution) with the separation efficiency above 99.5 % and the permeating flux up to 934 L m-2 h-1. The WBP-coated membrane not only removes crude oil from oily wastewater, but also realizes the recycling of waste resources.