Magnetic porous graphene/multi-walled carbon nanotube beads from microfluidics: a flexible and robust oil/water separation material

Abstract

In this paper, magnetic porous graphene/multi-walled carbon nanotube beads (MPGCBs) were fabricated by a modified capillary microfluidic device. Polystyrene (PS) microspheres not only served as the hard templates to form uniform macropores, but were also beneficial for keeping the stability of spherical architecture. In the process of solidification, both graphene oxide (GO) and acidified multi-walled carbon nanotubes (aMWCNTs) enriched with carboxyl functional groups can form stable and uniform dispersion in the droplets. After the calcination treatment, the composite beads had excellent water resistance and robust mechanical properties. Moreover, due to the addition of the Fe₃O₄ nanoparticles, the beads also possessed the advantage of flexible operation, which can facilitate oriented movement and recycling of the absorbents, and promoted the collection and recovery of the useful pollutants. These multi-functional MPGCBs with interconnected macroporous structures showed high absorption capacity (up to 8–25 times their own weight) for various kinds of oils and organic solvents, relatively high separation efficiency and long-term recycle stability in the oil/water mixture separation process.