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Abstract: Fe3O4 spheres with loose structure assembled by nanospheres with diameters around 50nm are synthesized via a facile one-pot solvothermal method. Series of Fe3O4 morphologies are obtained by controlling the concentration of cetyltrimethylammonium bromide (CTAB). The saturation magnetization of Fe3O4 nanospheres is about 87.3emu/g. Adsorption ability and mechanism of all samples are investigated. Experiments demonstrate that adsorption capacity is closely related with the double impacts of electrostatic interactions and specific surface area. [Copyright &y& Elsevier]

Abstract: In this contribution, we compare the adsorption capacity of different MFe2O4 (M=Mn, Fe, Co, Ni) ferrite nanocrystals synthesized by hydrothermal method for Congo red (CR). It is the first time to give a comprehensive comparison and analysis of the adsorption capacity of ferrite nanocrystals with spinel structure for CR. Research indicates that the cations distribution of MFe2O4 ferrites is the most important factor to decide their adsorption capacity. Electrostatic absorption was conceived as the main adsorption mechanism. Meanwhile, the MFe2O4 nanoparticles exhibited a clearly ferromagnetic behavior under applied magnetic field, which allowed their high-efficient magnetic separation from wastewater. Furthermore, acetone is an effective desorption agent for desorption of MFe2O4 nanoparticles loaded by CR. All of the spinel ferrite nanocrystals possess good soft-magnetism, especially, CoFe2O4 nanocrystals exhibit a higher saturation magnetization of 86.1emug−1 as well as the outstanding adsorption capacity for CR. By the calculation of Langmuir isotherm model, the maximum adsorption capacity of CoFe2O4 for CR is 244.5mgg−1. [Copyright &y& Elsevier]

Abstract: This investigation was to increase the adsorption capacity of magnetite for Congo red (CR) by adulterating a small quantity of La3+ ions into it. The adsorption capability of nanocrystalline Fe3−x La x O4 (x =0, 0.01, 0.05, 0.10) ferrite to remove CR from aqueous solution was evaluated carefully. Compared with undoped magnetite, the adsorption values were increased from 37.4 to 79.1mgg−1. The experimental results prove that it is effectual to increase the adsorption capacity of magnetite by doped La3+ ions. Among the La3+-doped magnetite, Fe2.95La0.05O4 nanoparticles exhibit the highest saturation magnetization and the maximum adsorption capability. The desorption ability of La3+-doped magnetite nanoparticles loaded by CR can reach 92% after the treatment of acetone. Furthermore, the Fe3−x La x O4 nanoparticles exhibited a clearly ferromagnetic behavior under applied magnetic field, which allowed their high-efficient magnetic separation from wastewater. It is found that high magnetism facilitates to improve their adsorption capacity for the similar products. [Copyright &y& Elsevier]