Adsorption properties of Fe₃O₄/Kaolin magnetic composites for Cu²⁺

To facilitate Kaolin which was used to remove Cu²⁺ from waste water, the stripped Kaolin was prepared by ball milling and the Fe₃O₄/Kaolin magnetic composite was prepared by oxidative precipitation method. The morphology and composition of Fe₃O₄/Kaolin magnetic composite were characterized by laser particle size analyzer, SEM and XRD, respectively. The saturation adsorption capacity and magnetic separation recovery of Cu²⁺ was tested. It is demonstrated that 3.0 g Fe₃O₄ is the optimal amount as additive in Fe₃O₄/Kaolin magnetic composite to achieve improved adsorption ability (17.98 mg/g). The saturation magnetization reaches about 16.19 emu/g by hysteresis loop, which shows excellent magnetic response. In addition, the adsorption data of the Fe₃O₄/Kaolin magnetic composite were fitted by Langmuir and Freundlich adsorption isotherm. It is found that the adsorption behavior of Fe₃O₄/Kaolin for Cu²⁺ is basically consistent with the Langmuir adsorption isotherm model and the Freundlich adsorption isotherm model, indicating both monolayer adsorption and multi-layer adsorption are existed in the adsorption behavior of the Fe₃O₄/Kaolin magnetic composite for Cu²⁺.