【作者】 王丹；

【导师】 许仕荣；

【作者基本信息】 湖南大学 ， 市政工程， 2016， 硕士

【摘要】 纳米尺寸的铁氧化物因其具有高比表面积,在去除水中重金属中表现出优异的性能。但其本身易团聚的特性影响了其对重金属的去除效果。本文以合成一种低成本且相对不易团聚的铁氧化物为目的,利用带状形貌的物体相对不易团聚的特性,以带状氢氧化镁硫酸盐水合物为模板,使其和铁盐进行置换反应得到带状铁氧化物,并对该铁氧化物吸附去除Cr（Ⅵ）进行研究。首先在实验室中参考以往文献所用方法合成出氢氧化镁硫酸盐水合物纳米带。分别就合成过程中乙醇的使用比例、溶液中硫酸镁浓度、合成反应时的温度与时间等因素对合成物的影响进行了研究,制备出低成本的带状结构的氢氧化镁硫酸盐水合物。通过XRD和SEM的表征,证明了合成产物是氢氧化镁硫酸盐水合物（5Mg（OH）₂×MgSO₄×3H₂O）,形貌为带状。然后合成水铁矿纳米带。利用置换反应的原理使氢氧化镁硫酸盐水合物纳米带和铁盐反应生成带状的水铁矿纳米带。分别考察了合成条件中的铁盐种类、铁盐和氢氧化镁硫酸盐水合物纳米带的投加比例、水和乙醇的比例、合成所需时间等参数的影响。对合成产物进行XRD、SEM表征以及比表面积、零点电位的测定,结果证明了:合成产物是水铁矿（Fe₅HO₈×4H₂O）;形貌为带状,具体尺寸为:宽度在50²00nm之间,厚度为10⁵0nm,长度可达几十微米;BET比表面积为45.23m2/g;Zeta电位零点出现在pH=8左右。接着进行了水铁矿纳米带去除Cr（Ⅵ）的吸附实验。着重考察了吸附时间、pH值对水铁矿纳米带吸附去除Cr（Ⅵ）的影响,研究了水铁矿纳米带合成后放置一段时间其吸附性能的有效性以及单独氢氧化镁硫酸盐水合物纳米带模板对Cr（Ⅵ）的吸附效果。结果表明,水铁矿纳米带对Cr（Ⅵ）的吸附反应非常迅速,在酸性环境下有较好吸附效果。合成物放置一段时间后吸附效果保持不变,镁模板对Cr（Ⅵ）几乎没有吸附效果。当溶液pH值为4、环境温度为室温时,水铁矿纳米带对水中Cr（Ⅵ）的最大吸附容量可达47.17 mg/g。最后研究了水铁矿纳米带去除Cr（Ⅵ）的动力学模型、热力学模型。结果表明吸附过程能够较好的吻合准二级动力学模型和Langmuir模型。该吸附以化学吸附为主,吸附可自发进行。更多还原

【Abstract】 Nano-sized iron oxide because of its high specific surface area,exhibit excellent performance in the removal of heavy metals in water.But its easy to reunite the characteristics affect the removal efficiency of heav y metals.In this paper synthesized a kind of low cost and relatively difficult to reunite iron oxides,for the purpose of using banded morphology characteristics of the object relative to reunite,nanoribbons magnesium hydroxide sulfate hydrate as a templ ate,using the substitution reaction,make the template and molysite banded iron oxide after reaction,and the iron oxide adsorption removal of Cr（Ⅵ）were studied.First of all,this article in the lab reference method used in the literature synthesis of nanometer magnesium hydroxide sulfate hydrate zone.Separately on the use of synthetic process of ethanol proportion,magnesium sulfate concentration in the solution,synthetic reaction temperature and time on the composites were studied,the influence of the preparation of the low cost of banded structure of magnesium hydroxide sulfate hydrate.By XRD and SEM characterization,proved that the synthetic product is magnesium hydroxide sulfate hydrate（5Mg（OH）₂×MgSO₄×3H₂O）,morphology of nanoribbons.Then the synthetic ferrihydrite nanoribbons.By using the principle of substitution reaction to nanometer magnesium hydroxide sulfate hydrate zone and molysite reaction generates banded iron ore with water.Respectively the effects of the variety of synthetic conditions of iron,iron and magnesium hydroxide sulfate hydrate nanobelts and proportion of additive,the proportion of water and ethanol,the influence of synthesis parameters such as the time required.On synthesis product of XRD,SEM and the determination of specific surface area,zero potential,the results proved that the synthetic product is ferrihydrite（Fe₅HO₈×4H₂O）;morphology for the nanoribbons,the specific size for: width between 50 200 nm,thickness of 10 50 nm,length can reach tens of microns;BET specific surface area of 45.23 m2 / g;Zeta potential zero is pH = 8.Then the water iron ore nanobelts and removal of Cr（Ⅵ）adsorption experiment.Adsorption time,pH value is mainly influence on ferrihydrite ferrihydrite nanoribbons,studying the iron ore nanobelts and synthetic water placed a period of time after the effectiveness of its adsorption properties and nanoscale magnesium hydroxide sulfate hydrate alone template for Cr（Ⅵ）adsorption effect.The results showed that the water iron ore nanobelts and adsorption of Cr（Ⅵ）reaction time very quickly,has good adsorption effect under acid environment.Synthetic placed after a period of time the adsorption effect remains the same,magnesium template almost no adsorption effect of Cr（Ⅵ）.When the solution pH value of 4,the environment temperature to room temperature,water iron ore nanobelts,maximum adsorption capacity of Cr（Ⅵ）in water can be up to 47.17 mg/g.Finally ferrihydrite nanoribbons was studied with the removal of Cr（Ⅵ）dynamic model,thermodynamic model and related parameters.Research results show that the adsorption process to better match level 2 dynamic model and the Langmuir model.The adsorption mainly chemical adsorption,adsorption can be spontaneous.更多还原