碳包覆磁性纳米胶囊的吸附性能研究

发布时间：2018-10-07 19:04

【摘要】：碳材料因物理化学性能稳定,比表面积大,孔隙结构发达等特点成为一直以来研究最多的吸附剂,包括活性炭、碳纤维、碳纳米管和石墨烯等。但是这些材料都存在难分离而重复利用的问题,因此开发具有成本低、吸附量大、脱附简单、可以循环利用的吸附剂具有重要意义。近年来,具有分离简单易操作的磁分离技术引起了越来越多的关注和兴趣,尤其是高饱和磁化强度的碳包覆磁性纳米粒子。本论文采用直流电弧等离子体法原位制备碳包覆铁纳米胶囊(Fe@C NCs)和碳包覆镍纳米胶囊(Ni@C NCs),利用过氧化氢对其进行表面改性处理,在其表面碳上嫁接含氧官能团,改变浸润性提高亲水性和分散性。透射电子显微镜(TEM)表征显示Fe@C NCs和Ni@C NCs为明显的核/壳结构,Fe@C NCs粒子大小约为20-50 nm,碳层厚度5-7 nm；Ni@C NCs粒子大小约为10-30nm,碳层厚度2-5 nm。测试Fe@C NCs 和 Ni@C NCs的氮气吸脱附等温曲线,采用多点BET法计算它们的比表面积分别为85.86m2/g和38.82m2/g。傅里叶变换红外光谱(FT-IR)证明过氧化氢处理成功在Fe@C NCs 和 Ni@C NCs的表面嫁接了含氧官能团,如羧基和羟基。同时,zeta电位测试也表明过氧化氢处理改变了Fe@C NCs 和 Ni@C NCs的表面电荷特征。将改性处理得到的Fe@C NCs和Ni@C NCs用作吸附剂,应用于染料亚甲基蓝(MB)和甲基橙(MO)的吸附研究。本论文系统地研究了染料初始浓度、吸附时间、pH值和温度对吸附量的影响。采用拟一级和拟二级动力学模型拟合吸附动力学过程,Langmuir和Freundlich模型分析吸附等温线,发现Fe@C NCs和Ni@C NCs对MB的吸附动力学更符合拟二级动力学,吸附等温线更符合Langmuir模型,根据此模型计算Fe@C NCs和Ni@C NCs对MB的最大单层吸附量分别为46.5 mg/g和20.6 mg/g。吸附热力学研究表明Fe@C NCs对MB的吸附是一个自发进行的吸附过程,而且以物理吸附为主。此外,还初步研究了Fe@C NCs和Ni@C NCs的脱附再生和循环利用性能,实验表明吸脱附进行5个循环,吸附剂仍表现出好的吸附性能,而且回收率很高。Fe@C NCs和Ni@C NCs作为一种新型吸附剂,将更有经济价值。
[Abstract]:Carbon materials have been the most widely studied adsorbents due to their stable physical and chemical properties, large specific surface area and well developed pore structure, including activated carbon, carbon fiber, carbon nanotubes and graphene. However, these materials are difficult to be separated and reused, so it is of great significance to develop adsorbents with low cost, large amount of adsorption, simple desorption and can be recycled. In recent years, magnetic separation technology with simple and easy to operate has attracted more and more attention and interest, especially carbon coated magnetic nanoparticles with high saturation magnetization. In this paper, carbon coated iron nanocapsules (Fe@C NCs) and carbon coated nickel nanocapsules (Ni@C NCs),) were prepared by DC arc plasma in situ. Change the wettability and improve the hydrophilicity and dispersity. Transmission electron microscopy (TEM) (TEM) characterization showed that Fe@C NCs and Ni@C NCs were obviously core-shell structure FeC NCs particles were about 20-50 nm, carbon layer thickness 5-7 nm;Ni@C NCs particle size 10-30 nm, carbon layer thickness 2-5 nm.. The nitrogen adsorption and desorption isotherms of Fe@C NCs and Ni@C NCs were measured. The specific surface areas of 85.86m2/g and Ni@C NCs were calculated by multipoint BET method and 38.82 m2 / g, respectively. Fourier transform infrared spectroscopy (FT-IR) showed that hydrogen peroxide was successfully grafted onto the surface of Fe@C NCs and Ni@C NCs with oxygen-containing functional groups such as carboxyl groups and hydroxyl groups. At the same time, the Zeta potential test also showed that hydrogen peroxide treatment changed the surface charge characteristics of Fe@C NCs and Ni@C NCs. The modified Fe@C NCs and Ni@C NCs were used as adsorbents to study the adsorption of methylene blue (MB) and methyl orange (MO). In this paper, the effects of initial dye concentration, adsorption time, pH value and temperature on the adsorption capacity were studied systematically. The adsorption isotherms were analyzed by using pseudo-first-order and pseudo-second-order kinetic models. It was found that the adsorption kinetics of Fe@C NCs and Ni@C NCs for MB was more in line with pseudo-second-order kinetics, and the adsorption isotherm was more suitable for Langmuir model. According to this model, the maximum monolayers adsorbed by Fe@C NCs and Ni@C NCs for MB were calculated to be 46.5 mg/g and 20.6 mg/g., respectively. The adsorption thermodynamics shows that the adsorption of MB by Fe@C NCs is a spontaneous adsorption process, and the physical adsorption is the main process. In addition, the desorption regeneration and recycling properties of Fe@C NCs and Ni@C NCs were preliminarily studied. The experimental results show that the adsorbents still exhibit good adsorption performance, and the recoveries of the adsorbents are very high. Fe@ C NCs and Ni@C NCs are used as a new adsorbent. Will have more economic value.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;O647.33

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