A trifecta membrane modified by multifunctional superhydrophilic coating for Oil/Water separation and simultaneous absorption of dyes and heavy metal

Adsorption and separation are the most important chemical engineering processes for wastewater treatment. Exerting microfiltration membranes as the central separation technology and decorating them with absorption property, forming absorptive membranes, result in the separation and purification of diverse wastewaters in an energy-efficient manner. Herein, a versatile polyanionic coating with superhydrophilicity/underwater superoleophobicity, superior anti-oil-fouling, and efficient charges is acquired through mussel-inspired co-deposition, followed by b-PEI functionalization, N-alkylation, and anionization. Thanks to the superhydrophilicity/underwater superoleophobicity, the as-prepared microfiltration membrane achieves selective separation of oil/water emulsions. Meanwhile, the functional membranes exhibited excellent selective and efficient adsorption capacity for organic dyes and heavy metal ions due to the abundant surface charges. Interestingly, benefiting from superhydrophilicity and considerable surface charges, the as-designed microfiltration membrane can realize selective and efficient simultaneous adsorption and separation of wastewaters with complicated components, including oil/water emulsions, organic dyes, and heavy metal ions by the concept of "achieving three things at one stroke". Such a versatile and feasible strategy could pave a new path for constructing multifunctional membranes for complex wastewater treatment and purification.