Recycling waste dredged sludge into bifunctional coating for one-step separation of multitasking dye contaminated oil/water emulsions.

[Display omitted] • A waste-to-treasure recycling strategy was presented to covert WDS into bifunctional coating. • WDS-PVDF membrane can effectively remove emulsified oil (> 99.3 %) and dye (MB, > 99.5 %) in one step. • Facile procedure, low-cost raw material, and green solvent promote large-scale fabrication. • WDS coating endowed underwater ultra-low oil adhesion (UWOCA of ∼170°, SA < 3°) and anti-oil-fouling performance. • It offers a new method for waste sludge recycling and dye contaminated oil/water separation. Effective strategies for disposing of waste dredged sludge (WDS) and separating multitasking oil/water emulsions in one way are in urgently demand but still insufficient. Herein, a bifunctional waste dredged sludge-coated polyvinylidene fluoride membrane (WDS-PVDF membrane) was prepared via vacuum filtration for one-step separation of emulsified oil and water-soluble dye. Compared with traditional membranes, WDS-PVDF membrane has advantages in the selected green solvent, low-cost raw materials, and facile fabrication process. Without chemical modification, hierarchical roughness and unique chemical composition endowed the membrane extraordinary underwater superoleophobicity and anti-oil-fouling performance. Significantly, the membrane could separate emulsified oil and water-soluble dye in one step with high separation efficiency (for emulsified oil: > 99.3 %, and for methylene blue: > 99.5 %). Therefore, this work not only offers an effective strategy for large-scale recycling and reutilization of waste sludge, but also for practical complex oily wastewater treatment. [ABSTRACT FROM AUTHOR]