镁基氢氧化物湿化学法制备及其染料吸附性能研究

发布时间：2019-02-12 10:35

【摘要】：随着人类社会、科技以及工业的快速发展,地球生态环境遭到了极大的破坏,尤其是水资源受到了严重的污染。印染、造纸、服装、食品以及塑料行业大量使用有机染料,而这些有机染料会随着这些行业的工业废水排放进入自然界的水循环系统,破坏水中动植物的生态环境,甚至会危害人类的身体健康。因此急需无污染、高效、经济实用的废水处理材料和方法来解决废水中的染料问题。物理吸附被认为是一种环境友好、效果显著的水中染料处理手段。19世纪中叶以来,镁基氢氧化物受到广泛关注,它被称为“绿色安全的大自然净化剂”,其对染料的优秀吸附性能,较大的比表面积以及无污染的特性使它成为一种潜力巨大的物理吸附材料。本论文采用湿化学法制备了氧化石墨烯-氢氧化镁纳米片复合材料和镁铝层状双氢氧化物,并研究了它们对水中阴离子型染料刚果红的吸附性能。首先以硝酸镁和氧化石墨烯(graphene oxide,GO)为前驱体,氢氧化钠和氨水混合物为沉淀剂,草酸钠为添加剂通过一步水热制备出GO-Mg(OH)2复合材料。通过测试复合材料对刚果红染料的吸附性能,研究了氧化石墨烯的加入量对于氢氧化镁纳米片吸附染料性能的影响。研究结果表明氧化石墨烯的加入可以增加氢氧化镁纳米片的比表面积,有助于提高其染料吸附性能,并发现当加入0.5%wt的GO时复合材料的吸附性能最佳。同时复合材料对于刚果红染料的吸附实验研究表明该材料对于染料的吸附动力学符合准二级动力学模型,其吸附热力学符合Langmuir热力学模型。吸附活化能实验结果显示GO-Mg(OH)2复合材料对于刚果红染料的吸附过程属于物理吸附。镁铝层状双氢氧化物(Mg/Al layered double hydroxide,Mg/Al LDHs)是以硝酸镁和硝酸铝为前驱体,氢氧化钠为沉淀剂,十二烷基苯磺酸钠(dodecylbenzenesulfonate,DBS)为添加剂,通过一步沉淀法制备得到的,并与氢氧化镁与氢氧化铝对比研究了它们对于刚果红染料的吸附性能。研究结果显示Mg/Al LDHs吸附刚果红染料的动力学实验数据符合准二级动力学模型,并且热力学实验证明它的吸附热力学过程符合Langmuir单分子层吸附。吸附活化能实验计算得出其吸附活化能为32.9 kJ mol-1,证明吸附类型属于物理吸附。通过与单金属氢氧化物对比显示镁铝层状双氢氧化物拥有更高的吸附活性,因为Mg/Al LDHs具有的特殊层状结构和层间带有的正电荷使它更易吸附刚果红阴离子染料。循环活性实验证明它是一种稳定、易再生、循环性能优越的染料吸附材料。
[Abstract]:With the rapid development of human society, science and technology and industry, the ecological environment of the earth has been greatly damaged, especially the serious pollution of water resources. The printing and dyeing, papermaking, clothing, food and plastics industries use organic dyes in large quantities, and these organic dyes are discharged into the natural water circulation system with the industrial wastewater from these industries, damaging the ecological environment of plants and animals in the water. It can even endanger human health. Therefore, no pollution, high efficiency, economic and practical wastewater treatment materials and methods are urgently needed to solve the dye problem in wastewater. Physical adsorption is considered to be an environmentally friendly and effective means of dye treatment in water. Since the middle of the 19th century, magnesium hydroxide has received widespread attention and is known as a "green and safe nature purifier". Because of its excellent adsorption performance, large specific surface area and no pollution, it has become a potential physical adsorption material. In this paper, graphene oxide / magnesium hydroxide nanocomposites and magnesium aluminum layered double hydroxides were prepared by wet chemical method, and their adsorption properties for Congo red, an anionic dye in water, were studied. Firstly, magnesium nitrate and graphene oxide (graphene oxide,GO) were used as precursors, the mixture of sodium hydroxide and ammonia as precipitant and sodium oxalate as additive to prepare GO-Mg (OH) _ 2 composites by one-step hydrothermal treatment. The influence of the amount of graphene oxide on the adsorption of Congo red dyes on magnesium hydroxide nanoparticles was studied by measuring the adsorption properties of Congo red dyes. The results show that the addition of graphene oxide can increase the specific surface area of magnesium hydroxide nanoparticles and help to improve the adsorption properties of the dyes. It is also found that the composite material has the best adsorption performance when GO is added with 0.5%wt. At the same time, the adsorption kinetics of the composite materials for Congo red dyes was found to be in accordance with the quasi-second-order kinetic model, and the adsorption thermodynamics was in accordance with the Langmuir thermodynamic model. The results of adsorption activation energy experiments show that the adsorption of Congo red dyes by GO-Mg (OH) _ 2 composite is a physical adsorption process. Magnesium aluminum layered double hydroxides (Mg/Al layered double hydroxide,Mg/Al LDHs) were prepared by one step precipitation method using magnesium nitrate and aluminum nitrate as precursors, sodium hydroxide as precipitant and sodium dodecyl benzene sulfonate (dodecylbenzenesulfonate,DBS) as additive. Compared with magnesium hydroxide and aluminum hydroxide, the adsorption properties of Congo red dyes were studied. The results show that the kinetic data of adsorption of Congo red dyes by Mg/Al LDHs accord with the quasi-second-order kinetic model, and the thermodynamic experiments show that the adsorption thermodynamic process accords with the adsorption of Langmuir monolayers. The adsorption activation energy was calculated by experiments. The adsorption activation energy is 32. 9 kJ mol-1,. It is proved that the adsorption type belongs to physical adsorption. Compared with monometallic hydroxides, Mg-Al layered double hydroxides have higher adsorption activity, because Mg/Al LDHs has special layered structure and positive charge between layers, which makes it easier to adsorb Congo red anion dyes. It is proved by cyclic activity experiment that it is a stable, easy to regenerate and excellent cycling dye adsorption material.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;TQ424

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