Effect of magnetite nanoparticles on dye absorption properties of magnetite@carbon composites

Magnetite@carbon (Fe 3 O 4 @C) composites were prepared using three kinds of Fe 3 O 4 nanoparticles (NPs). All the Fe 3 O 4 @C composites could be easily separated from water by an external magnet. The Fe 3 O 4 NPs synthesized by a microreactor system have the smallest size and narrowest size distribution among the three kinds of Fe 3 O 4 NPs. The saturated capacity of the Fe 3 O 4 @C composite originating from microreactor-prepared Fe 3 O 4 NPs to absorb Rhodamine B at 2 0 ∘ C exceeds 135 mg g − 1 , which is 1.35 times as much as the value of the Fe 3 O 4 @C composite originating from traditional Fe 3 O 4 NPs. This value for the Fe 3 O 4 @C composite using commercial Fe 3 O 4 NPs as core is only 76 mg g − 1 . The Fe 3 O 4 @C composite using microreactor-prepared Fe 3 O 4 NPs also has good retrievability and reusability.