改性硅藻土去除水中重金属和磷酸盐的研究

发布时间：2018-06-06 02:05

  本文选题：硅藻土 + 磁分离　； 参考：《济南大学》2017年硕士论文

【摘要】：目前,重金属和磷酸盐污染由于其对生态和人体的众多不利影响,已成为全世界关注的话题之一。吸附法由于其操作的简单性和灵活性、低廉的价格、良好的选择性和再生能力可被用于水中重金属和磷酸盐的去除,而应用的关键在于寻找一种高效、友好、经济的吸附剂。硅藻土由于其低价易得、多孔性、良好的渗透性和热稳定性等优点被认为是一种理想的吸附剂,但是较低的去除能力和分离的困难极大地限制了它的应用,需要寻求一些合适的方法提高硅藻土的性能,如将硅藻土与具有良好络合能力的氨基官能团和较强超顺磁性的Fe_3O_4结合在一起,将是一种理想的解决方法。首先,本文采用一步溶剂热法将Fe_3O_4纳米颗粒负载至硅藻土(diatomite,DTM)表面,合成了氨基化磁性硅藻土复合材料(Fe_3O_4/DTM),并对其进行了粉末X射线衍射(XRD)、红外光谱(FTIR)、X射线光电子能谱(XPS)、扫描电镜/透射电镜/能谱(SEM/TEN/EDS)、比表面积(BET)和磁滞回归曲线(VSM)等表征。结果表明:大量的纳米Fe_3O_4微球已经成功负载至拥有不同孔结构的圆盘状DTM表面,介孔状Fe_3O_4/DTM合成成功;合成材料晶型良好,功能化官能团丰富(如羟基、氨基),比表面积、孔容和孔径较大(50.3 m2/g、0.2408 cm3/g、8.7 nm),超顺磁性较强(26.89 emu/g),能够保证Fe_3O_4/DTM的良好吸附性能和分离性能。然后,将Fe_3O_4/DTM应用于水中Pb~(2+)、Cd~(2+)和Cu~(2+)的去除,通过实验条件的改变、动力学和等温线模型及相关的表征手段研究了其吸附条件、性能和机理。结果表明:Fe_3O_4/DTM对于Pb~(2+)、Cd~(2+)和Cu~(2+)的吸附能力相比于DTM有了极大的提高,20 min时便可达到吸附平衡,受溶液中Na+、K+、Mg~(2+)、Ca~(2+)等的影响较小。吸附动力学符合拟二级动力学,内部扩散阶段主导着整个过程的反应速率;吸附等温线符合Langmuir和Temkin模型,是一个易进行的均相单层的化学吸附过程,最大理论吸附量分别为51.65、42.17和7.12 mg/g。Zeta电位和XPS表征证实Fe_3O_4/DTM主要通过静电作用、表面络合和离子交换作用实现对Pb~(2+)、Cd~(2+)和Cu~(2+)的去除。此外,在吸附后吸附剂Fe_3O_4/DTM在磁场作用下可实现快速分离,并且吸附质在酸处理后可得到回收。最后,将Fe_3O_4/DTM应用于水中磷酸盐的去除,详细研究了Fe_3O_4/DTM吸附磷酸盐的最优条件、性能及机理。结果表明:Fe_3O_4/DTM对磷酸盐的吸附在30 min时便可达到平衡,吸附过程受溶液pH值的影响,酸性条件下效果较好并且吸附后溶液pH值稳定在8左右。吸附动力学和吸附等温线分别符合拟二级动力学和Langmuir模型,内部扩散阶段主导着整个过程的反应速率,最大理论吸附容量为11.89 mg/g。吸附机理为静电吸引和配体交换。综上所述,Fe_3O_4/DTM很容易由低廉丰富的硅藻土合成,合成的材料拥有优秀的吸附、再生和分离性能,是一个良好的重金属和磷酸盐吸附剂,展现出良好的应用前景。
[Abstract]:At present, heavy metal and phosphate pollution has become one of the topics of worldwide concern because of its many adverse effects on ecology and human body. The adsorption method can be used to remove heavy metals and phosphate in water because of its simplicity and flexibility, low price, good selectivity and regeneration ability. The key to its application is to find an efficient, friendly and economical adsorbent. Diatomite is considered to be an ideal adsorbent because of its advantages of low price, porosity, good permeability and thermal stability, but its application is greatly limited by its low removal capacity and separation difficulties. It is necessary to find some suitable ways to improve the properties of diatomite, such as combining diatomite with amino functional groups with good complexing ability and strong superparamagnetic Fe_3O_4, which is an ideal solution. Firstly, Fe_3O_4 nanoparticles were loaded onto diatomite Fe_3O_4 surface by one-step solvothermal method. The Amino magnetic diatomite composite was synthesized and characterized by powder X-ray diffraction (XRD), infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) / transmission electron microscopy (TEM) / energy dispersive electron microscopy (EDS), specific surface area (BET) and hysteresis regression curve (VSM). The results show that a large number of nanocrystalline Fe_3O_4 microspheres have been successfully loaded to the disk DTM surface with different pore structures, and mesoporous Fe_3O_4/DTM has been synthesized successfully, and the synthesized materials have good crystal form and abundant functionalized functional groups (such as hydroxyl, amino acid, specific surface area, etc.) The pore volume and pore size of 50.3 m ~ 2 / g ~ (-1) 0.2408 cm ~ (-3) / g ~ (8.7) nm ~ (-1), with a strong superparamagnetism of 26.89 emu / g ~ (-1), can guarantee the good adsorption and separation performance of Fe_3O_4/DTM. Then, Fe_3O_4/DTM was applied to the removal of Pb~(2 and Cu~(2 in water. The adsorption conditions, properties and mechanism were studied by the change of experimental conditions, kinetics, isotherm model and related characterization methods. The results show that the adsorptive capacity of Fe3O / DTM for Pb~(2 and Cu~(2) can reach equilibrium when compared with that of DTM for 20 min, and is less affected by Na ~ (3) K ~ (2) mg ~ (2) ~ (2) ~ (+) ~ (2) ~ (2). The adsorption kinetics accords with the pseudo-second-order kinetics, the internal diffusion stage dominates the reaction rate of the whole process, and the adsorption isotherm accords with the Langmuir and Temkin models, which is a homogeneous monolayer chemisorption process. The maximum theoretical adsorption amounts were 51.65N 42.17 and 7.12 mg/g.Zeta potential and XPS characterization, respectively. The results show that the removal of Pb~(2 and Cu~(2 by Fe_3O_4/DTM is mainly achieved by electrostatic interaction, surface complexation and ion exchange. In addition, the adsorbent Fe_3O_4/DTM can be separated rapidly under the action of magnetic field after adsorption, and the adsorbate can be recovered after acid treatment. Finally, Fe_3O_4/DTM was applied to the removal of phosphate in water, and the optimum conditions, properties and mechanism of phosphate adsorption by Fe_3O_4/DTM were studied in detail. The results show that the adsorption of phosphate by 10% Fe3ODTM can reach equilibrium at 30 min. The adsorption process is affected by pH value of solution, and the pH value of solution is stable at about 8 after adsorption under acidic condition. The adsorption kinetics and adsorption isotherm accord with pseudo-second-order kinetics and Langmuir model respectively. The internal diffusion stage dominates the reaction rate of the whole process and the maximum theoretical adsorption capacity is 11.89 mg / g. The adsorption mechanism is electrostatic attraction and ligand exchange. To sum up, it is very easy to synthesize Fe3O4 / DTM from cheap and abundant diatomite. The synthesized material has excellent adsorption, regeneration and separation properties. It is a good adsorbent for heavy metals and phosphate, and has a good application prospect.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52

【参考文献】

中国期刊全文数据库 前3条

1 郑莹;潘杨;周晓华;廖p芎，

本文编号：1984509