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Abstract: Here, we are going to report a simple, low-cost and environmental friendly process to prepare catenulate flowery iron (Fe). Magnetite (FeFe2O4) with similar 3D morphology is gained at room temperature for the first time by aging of iron in water. The saturation magnetizations of these two products are totally high, which are 121.59emu/g for Fe and 90.2emu/g for FeFe2O4. It is not usual for Fe3O4 with lamellar structure because magnetic saturation for well defined Fe3O4 single crystals is 92emu/g. Because of the special appearance with large surface area, adsorption experiments of organic dye, sulfonamide and heavy metal ions are carried out in synthetic wastewater. Adsorption rate of two magnetic samples—iron and magnetite—can achieve more than 98% in 5min. It is worthy to note that, in adsorption experiment of CrVI, the adsorption rate of Fe can achieve 100% in 5min. The equilibrium times of all productions can be controlled in a short span of 30min. Achieve high performance of adsorption in a short time, which perform a great advantage in water treatment applications of such materials. Finally, regeneration experiments of FeFe2O4 which adsorbed Congo red show that the as prepared sample can be well-regenerated, and after regeneration, the magnetic adsorbents can still show more than 97.6% adsorption capacity. [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]