Durable, magnetic-responsive melamine sponge composite for high efficiency, in situ oil–water separation

The development of durable and high-performance absorbents for in situ oil–water separation is of critical importance for addressing severe water pollution in daily life as well as for solving accidental large-scale oil spillages. Herein, we demonstrate a simple and scalable approach to fabricate magnetic-responsive superhydrophobic melamine sponges by in situ deposition of PDA coatings and Fe 3 O 4 nanoparticles, followed by surface silanization with low surface energy 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PTOS) layer. The prepared melamine sponge composite (PTOS-Fe 3 O 4 @PDA/MF) not only exhibits a very high water contact angle of 165 ± 1.5° and an excellent ability to uptake a variety of oils and organic solvents (e.g. up to 141.1 g/g for chloroform), but also shows robust durability and superior recyclability. The PTOS-Fe 3 O 4 @PDA/MF sponge can also efficiently separate oils (or organic solvents) and water, as demonstrated by different model systems including immiscible oil–water solution mixture and miscible water–oil (W/O) emulsion (stabilized by surfactants). Furthermore, the PTOS-Fe 3 O 4 @PDA/MF sponge is able to in situ recover organics from water using a peristaltic pump, which gives it significant advantages over other traditional batch processes for oil–water separation. We believe that the PTOS-Fe 3 O 4 @PDA/MF sponge provides a very promising material solution to address oil–water separation, especially for the large-scale problems that have been long-time challenges with conventional sorption methods.