壳聚糖季铵盐改性石墨烯的制备及其吸附性能研究

发布时间：2019-06-11 21:49

【摘要】：石墨烯具有化学稳定性好和比表面积大等特点,成为吸附应用方面的研究热点。而水溶性的壳聚糖季铵盐呈阳离子,能通过静电作用吸附废水中的污染物。因此,本文结合石墨烯和壳聚糖季铵盐两者的优势,通过非共价静电作用制备壳聚糖季铵盐改性的石墨烯(HACC-RGO),希望提高石墨烯在水溶液中的分散性、稳定性,以及赋予石墨烯更好的吸附性能。首先,壳聚糖季铵盐(HACC)通过静电作用与氧化石墨烯(GO)结合,然后利用水合肼还原得到HACC改性的石墨烯(HACC-RGO)。采用红外光谱、X射线衍射和扫描电子显微镜对HACC-RGO进行结构和形貌的表征,热重测试分析改性剂HACC在HACC-RGO中的实际含量,Zeta电位分析仪对比不同改性石墨烯的Zeta电位值,并通过动态光散射粒径仪研究HACC-RGO在不同pH值溶剂中的分散性及粒径大小。结果表明,HACC成功结合到石墨烯表面上并插入石墨烯片层间,HACC-RGO中HACC的含量随着HACC用量的增大而增加,Zeta电位值也随之增加,而相应HACC-RGO的粒径减小。得到的HACC-RGO在pH为2-9的水溶液中均能稳定分散。通过循环伏安法研究HACC-RGO的电化学性能,结果表明HACC-RGO具有较好的导电性。然后,通过紫外可见分光光度法研究HACC-RGO粉末对甲基橙溶液的吸附效果,探讨吸附时间、pH、温度和吸附剂用量等因素对HACC-RGO吸附甲基橙的影响。结果表明,HACC-RGO对甲基橙的吸附率远高于RGO和HACC对甲基橙的吸附率。HACC-RGO吸附甲基橙8h可以达到平衡状态,升高温度有利于对甲基橙的吸附。HACC-RGO对甲基橙的吸附遵从准二级动力学吸附模型,吸附速率主要受颗粒表面扩散速度的影响,吸附过程更符合Freundlich等温吸附模型,主要为物理吸附。最后,基于HACC-RGO通过超声分散在乙酸(0.2mol/L)溶液中的特点,通过微流控技术制备HACC-RGO/壳聚糖(CS)小球。采用X射线衍射、三维视频显微镜、热重分析和扫描电镜对HACC-RGO/CS小球进行结构和形貌的表征,HACC-RGO/CS小球为规则的球形,其中改性石墨烯实际含量与理论值接近。研究了HACC-RGO/CS小球和CS小球对甲基橙的吸附效果,结果表明HACC-RGO小球对甲基橙的吸附率为91.89%,在水和2wt%NaOH溶液中对甲基橙的解吸率分别为11.32%和87%。
[Abstract]:Graphene has become a hot research topic in adsorption applications because of its good chemical stability and large specific surface area. The water-soluble chitosan quaternary ammonium salt is cationic and can adsorb pollutants in wastewater by electrostatic action. Therefore, based on the advantages of graphene and chitosan quaternary ammonium salt, graphene modified by chitosan quaternary ammonium salt (HACC-RGO) was prepared by non-covalent electrostatic action in the hope of improving the dispersion and stability of graphene in aqueous solution and giving graphene better adsorption properties. Firstly, chitosan quaternylammonium salt (HACC) binds to graphene oxide (GO) by electrostatic interaction, and then HACC modified graphene (HACC-RGO) is obtained by reduction with hydrazide hydrate. The structure and morphology of HACC-RGO were characterized by infrared spectroscopy, X-ray diffraction and scanning electron microscope. The actual content of modifier HACC in HACC-RGO was measured by thermogravimetric analysis. The Zeta potential values of different modified graphene were compared by Zeta potential analyzer, and the dispersion and particle size of HACC-RGO in different pH solvents were studied by dynamic light scattering particle size meter. The results show that HACC is successfully bonded to graphene surface and inserted into graphene lamella. the content of HACC in HACC-RGO increases with the increase of HACC dosage, and the potential value of Zeta increases, while the particle size of HACC-RGO decreases. The obtained HACC-RGO can be stably dispersed in aqueous solution with pH of 2 鈮，

本文编号：2497475