Superhydrophobic magnetic hollow carbon microspheres with hierarchical micro/nano-structure for ultrafast and highly-efficient multitasking oil-water separation

Abstract Nowadays, developing separation materials for oil-water mixture and even emulsion have drawn extensive interest, with increasing oily wastewater pollution. Among kinds of separation materials, hydrophobic magnetic particles can rapidly and high-efficiently separate oil from either oil-water mixtures or emulsions. However, they not only commonly suffer from complicated preparation procedures and poor resistance to harsh conditions, but also are almost unable to satisfy the demand of multitasking separations towards oil-water mixtures and micro/nanoemulsions with surfactant. Herein, a facile, simple and scalable approach is introduced to prepare superhydrophobic magnetic hollow carbon microspheres (SMHCMs) with micro/nano hierarchical surface. Thanks to the special wettability properties, micro/nano hierarchical surface, nano-porous shell and hollow cores, the as-prepared SMHCMs show an unprecedented absorption capacity of over 10 g/g for oil-water mixtures within an absorption time of 60 s as well as a superior separation efficiency of near 99% for surfactant-free and surfactant-stabilized micro/nanoemulsions at an extremely short time of as low as 10 s. In addition, the SMHCMs also possess stable performance, good reusability, durability and resistance to harsh environments (e.g., acidic, alkaline and high-saline). This work proposes a new prospect for designing advanced materials applied to the fast and highly-efficient oil-water separation.