Designing multifunctional 3D magnetic foam for effective insoluble oil separation and rapid selective dye removal for use in wastewater remediation

Abstract

Highly-efficient separating materials, which can simultaneously remove oil from water and adsorb water-soluble contaminants like dyes, are in high demand for wastewater treatment. Herein, a magnetic, multifunctional melamine foam (MF) containing Fe₃O₄ nanoparticles, poly(sulfobetaine methacrylate) (PSBMA) and polydopamine (PDA) was fabricated via a simple mussel-inspired one-pot process, which not only can separate oil/water mixtures and emulsions but also has cationic-dye selective separation abilities. The addition of poly(sulfobetaine methacrylate) (PSBMA) allows immobilization to bind Fe₃O₄ nanoparticles tightly on the surface of the melamine foam skeleton so as to endow the 3D foam with superoleophobicity underwater, as well as providing active sites for the adsorption of soluble dyes in water. The special material synergy makes the resultant magnetic MF@Fe₃O₄@PDA/PSBMA foam quickly absorb cationic dyes and allows for the selective removal (in 2 minutes) of cationic dyes from dye mixtures with high efficiency (>96%), high stability and flexibility even after 10 cycles, when driven by a magnet. Furthermore, the developed 3D magnetic foam is able to separate oil–water mixtures in highly acidic, alkaline, and salty environments. Our strategy may open a new avenue to obtain high-performance 3D magnetic assemblies for wastewater remediation.