纳米Co/rGO磁性复合吸附材料的制备及对Cu2+的吸附性能

以改进Hummer法制备的薄片状氧化石墨烯(GO)为载体和模板负载钴离子，然后采用原位还原法制得纳米金属Co/石墨烯磁性复合吸附材料(Co/rGO)，并将其应用于对Cu2+的吸附和脱除，以期为高效可复用的铜离子脱除剂的合成与应用提供指导。实验结果证实，Co/rGO复合材料具有超顺磁性，能够很方便的使用磁铁进行分离并在无磁场情况下振荡分散。Co/rGO复合材料对Cu2+具有稳定的吸附/脱附性能，实验条件下对Cu2+的最大吸附容量达到117.5 mg/g且5 min内实现吸附平衡，远优于其原料GO的60 min吸附容量27.6 mg/g。本工作系统考察了NaOH加入量、络合剂种类、溶剂种类等关键因素对Co粒子在rGO载体上形貌和分布特性的影响，比较了不同合成条件下的复合材料对Cu2+吸附效果的影响，并对优选条件下制备的Co/rGO复合材料进行了FT-IR, XRD, SEM表征。研究结果表明，纳米Co/rGO磁性材料对Cu2+的吸附过程更符合Freundlich模型，属于多层吸附。室温下吸附焓ΔH=17.81 kJ/mol，吸附反应平衡常数Kθ=3.65。当初始Cu2+浓度为39.22 mg/L时，对Cu2+的吸附率为93.47%，五次吸附/脱附循环后吸附容量仍保持在初始值的94%，每次吸附后溶液中残余Cu2+浓度均满足钴电解液对杂质铜离子的浓度去除要求(5 mg/L)或GB 8978-1996污水综合排放标准3级(2 mg/L)，有望在相关领域发挥作用。

Preparation of nano Co/rGO magnetic materials and the adsorption properties to Cu2+ ions

Flaky graphene oxide (GO) prepared by the improved Hummer method was used as a carrier and template to load cobalt ions. Then, nano-metal Co/graphene magnetic composite adsorption material (Co/rGO) was prepared using in situ reduction method and was applied to adsorb and remove Cu2+ to provide the guidance for the synthesis and application of remover with efficient and reusable copper ion. The experimental results showed that Co/rGO composite materials had super paramagnetism, and could be easily separated by magnets as well as be oscillating dispersed without magnetic field. Co/rGO composite materials had stable adsorption and desorption properties for Cu2+. The maximum adsorption capacity for Cu2+ could reach 117.5 mg/g under experimental conditions and the adsorption balance could be achieved within 5 min, which was far superior to its raw material GO with the adsorption capacity of 27.6 mg/g in 60 min. In this work, the key factors including the amount of NaOH addition, the type of complexant, and the type of solvent on the morphology and distribution characteristics of Co particles on rGO carrier were systematically investigated. The adsorption effects for Cu2+ of composite materials under different synthesis conditions were compared. The properties of Co/rGO composite materials prepared in preferred conditions were characterized by FT-IR, XRD and SEM. The results showed that the adsorption process of Cu2+ by nano-Co/rGO magnetic materials was more consistent with Freundlich model and belonged to multilayer adsorption. The adsorption enthalpy ΔH was 17.81 kJ/mol, and the equilibrium constant of adsorption reaction Kθ was 3.65 at room temperature. When the initial concentration of Cu2+ was 39.22 mg/L, the desorption rate exceeded 93%, and initial value of adsorption capacity remained at 94% after five adsorption/desorption cycles. The residual concentration of Cu2+ in the solution after each adsorption always met the requirements of cobalt electrolyte for the removal of impurity copper ions (5 mg/L) or GB 8978-1996 level 3 (2 mg/L) of comprehensive sewage discharge, which was expected to play a role in related fields.