Hierarchical Fe3O4/C with a flower-like morphology: A highly efficient and reusable dye adsorbent

Hierarchical Fe3O4/C (h-Fe3O4/C) with a flower-like morphology was successfully prepared using a facile hydrothermal method, followed by annealing at 400 degrees C under N-2. The h-Fe3O4/C product consisted of radially assembled porous nanosheets (thickness similar to 53 nm) and exhibited improved adsorption ability for cationic rhodamine B (RhB) over a wide pH range compared with other forms of Fe3O4/C. The excellent dye adsorption performance of h-Fe3O4/C could be attributed to its high specific surface area (113.6 m(2) g(-1)) and abundance of accessible adsorption sites for dye molecules on the porous nanosheets. In addition, h-Fe3O4/C effectively adsorbed anionic and neutral dyes, suggesting both electrostatic and van der waals interactions underpinned its adsorption performance. Importantly, h-Fe3O4/C could be easily recovered from dye solutions by magnetic separation, and then regenerated by washing and heat treatment with no loss in adsorption capacity. Due to its low cost, ease of fabrication, excellent dye adsorption properties, rapid magnetic recovery and regeneration, h-Fe3O4/C represents a very promising adsorbent for large scale removal of organic dyes and other organic pollutants from water.