LAUSR

Magnetite@carbon (Fe3O4@C) composites were prepared using three kinds of Fe3O4 nanoparticles (NPs). All the Fe3O4@C composites could be easily separated from water by an external magnet. The Fe3O4 NPs synthesized by a microreactor system have the smallest size and narrowest size distribution among the three kinds of Fe3O4 NPs. The saturated capacity of the Fe3O4@C composite originating from microreactor-prepared Fe3O4 NPs to absorb Rhodamine B at 20∘C exceeds 135 mg g−1, which is 1.35 times as much as the value of the Fe3O4@C composite originating from traditional Fe3O4 NPs. This value for the Fe3O4@C composite using commercial Fe3O4 NPs as core is only 76 mg g−1. The Fe3O4@C composite using microreactor-prepared Fe3O4 NPs also has good retrievability and reusability.