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

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.