磁性多壁碳纳米管吸附去除水中Cu（Ⅱ）和亚甲基蓝的研究

发布时间：2018-07-29 10:48

【摘要】：在实际环境中有机物-重金属复合污染非常普遍,是构成环境污染重要的来源。而工业生产废水组成复杂多变,重金属铜和有机物亚甲基蓝同时存在的可能性很大。目前常用的处理废水的方法都有不同的局限性,而吸附法是一种重要的物理化学方法,在处理废水中有机物和无机物污染废水中有着广泛的应用。随着碳纳米管及纳米材料研究的深入其广阔的应用前景也不断地展现出来,研究者们研究了其对水中有机物和无机物的吸附,展现其比表面积大、粒径小、吸附容量大的优点。但吸附过后很难分离,排入水体不仅造成资源浪费而且广泛存在于环境中的碳纳米管的环境风险也应当被关注。近几年来,磁分离作为物理处理技术在水处理中获得了许多成功应用,显示出其高效、快速、经济等许多优点。本课题将磁分离技术应用于多壁碳纳米管的吸附,采用化学共沉淀的方法制备了磁性多壁碳纳米管(MMWCNT),测定了吸附剂的磁稳定性,用扫描电镜(SEM)、BET比表面积(SSA)、Zeta电位仪、X射线光电子能谱(XPS)对磁性多壁碳纳米管复合物进行了表征。研究了亚甲基蓝和铜在MMWCNT上的单一和竞争吸附。考察了一元体系中吸附动力学、吸附热力学及pH值对吸附性能的影响。进一步探究了吸附剂在河水水样中的效果,吸附剂回收率及循环利用的能力以及二元体系中亚甲基蓝和铜之间的竞争吸附现象。结果表明,铁氧化物纳米颗粒成功地覆盖在多壁碳纳米管表面,形成的MMWCNT易于磁性分离；MMWCNT的比表面积为139.86 m2/g；等电点为5.3。一元体系中,在4h时内对亚甲基蓝和铜的吸附达到平衡,吸附过程符合准二级动力学模型,等温吸附数据符合Langmuir模型,最大吸附量分别为46.03mg/g和27.74mg/g;pH值是影响吸附效果的重要因素；而且MMWCNT在环境水样中的吸附效果明显提高；MMWCNT具有较高的回收率,五次解吸循环实验后,MMWCNT对MB的平衡吸附量从45.5 mg/g降到34.2 mg/g,对于Cu(II)的平衡吸附量仍有17.6 mg/g,表明吸附性能仍然良好,MMWCNT有望运用于实际水处理中。竞争吸附过程中亚甲基蓝优先吸附,对Cu(II)的吸附有一定的抑制作用,当亚甲基蓝吸附平衡后,随着吸附剂量的增加铜的吸附效率从11.03%增到73%。
[Abstract]:Organic-heavy metal compound pollution is very common in the real environment, and it is an important source of environmental pollution. However, the composition of industrial wastewater is complex and changeable, and it is very likely that heavy metal copper and organic methylene blue exist at the same time. At present, the common methods of wastewater treatment have different limitations, and adsorption is an important physical and chemical method, which is widely used in the treatment of organic and inorganic pollutants in wastewater. With the further study of carbon nanotubes and nano-materials, their broad application prospects have been continuously demonstrated. Researchers have studied the adsorption of organic and inorganic compounds in water, showing the advantages of large specific surface area, small particle size and large adsorption capacity. However, it is difficult to separate after adsorption, and the environmental risk of carbon nanotubes (CNTs) which exist widely in the environment should also be paid attention to. In recent years, as a physical treatment technology, magnetic separation has been successfully applied in water treatment, showing its many advantages, such as high efficiency, fast and economical. In this paper, the magnetic separation technology was applied to the adsorption of multi-walled carbon nanotubes, and the magnetic stability of the adsorbent was determined by chemical coprecipitation method. The magnetic multiwalled carbon nanotubes (MCNTs) composites were characterized by scanning electron microscope (SEM) (SEM) BET specific surface area (SSA) / Zeta potentiometer and X-ray photoelectron spectroscopy (XPS). The single and competitive adsorption of methylene blue and copper on MMWCNT was studied. The effects of adsorption kinetics, adsorption thermodynamics and pH value on adsorption properties were investigated. The effect of adsorbent in river water, the recovery rate and recycling ability of adsorbent and the competitive adsorption between methylene blue and copper in binary system were investigated. The results show that the iron oxide nanoparticles are successfully covered on the surface of multi-walled carbon nanotubes, and the specific surface area and isoelectric point of MMWCNT are 139.86 m2 / g and 5.3, respectively. The adsorption of methylene blue and copper reached equilibrium within 4 hours, the adsorption process was in accordance with the quasi-second-order kinetic model, and the isothermal adsorption data was in accordance with Langmuir model. The maximum adsorption capacity of 46.03mg/g and pH value of 27.74 mg / g 路g / g were the important factors affecting the adsorption effect. Moreover, the adsorption efficiency of MMWCNT in environmental water samples was significantly improved, and the recovery rate of MMWCNT was higher. After five desorption cycles, the equilibrium adsorption capacity of MMWCNT to MB decreased from 45.5 mg/g to 34.2 mg / g, and the equilibrium adsorption capacity to Cu (II) was still 17.6 mg / g, indicating that the adsorption performance of MMWCNT is still good. Methylene blue preferentially adsorbed methylene blue and inhibited the adsorption of Cu (II). When methylene blue adsorbed equilibrium the adsorption efficiency of copper increased from 11.03% to 73% with the increase of adsorption dose.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X788

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