Composite Fe3O4/alpha-Fe2O3 nanorods (180N) with a specific surface area of 16.2 m(2)/g were successfully synthesized via a facile hydrothermal reaction at 180 degrees C. To increase the specific surface area, a mesoporous carbon aerogel (CA) with a large specific surface area was added to the hydrothermal reaction to form mesoporous Fe3O4/alpha-Fe2O3/CA structures (CA-180) with a specific surface area of 267.7 m(2)/g instead of nanorods. The as-prepared 180N and CA-180 samples were further annealed at 400 degrees C to oxidize the Fe3O4 phase, resulting in the formation of composite gamma-Fe2O3/alpha-Fe2O3 nanorods (400N) with a specific surface area of 27.7 m(2)/g and mesoporous gamma-Fe2O3/alpha-Fe2O3/CA structures (CA-400) with a specific surface area of 551 m(2)/g. The CA-400 samples were further used to remove the dye Rhodamine B (RhB) from aqueous solution, and 98.2% of the RhB dye was removed using the CA-400 sample when the initial RhB concentration was 8 ppm. The as-prepared CA-400 sample exhibits strong potential for use in wastewater treatment applications, such as organic dye removal. (C) 2015 Elsevier B.V. All rights reserved.