气助超顺磁分离技术去除废水中重金属污染物的研究

发布时间：2018-04-24 17:12

本文选题：重金属离子 + 超顺磁性纳米颗粒　；参考：《湘潭大学》2017年硕士论文

【摘要】：重金属污染物具有低浓度致毒、毒性持久、不可降解性和可通过食物链富集进入人体并在人体内累积等特点,进入水体会导致严重的环境污染问题。如何去除废水中的重金属污染物以消除其环境危害,是人们亟待解决的重要环境问题。在众多去除技术中,近年来,基于超顺磁性吸附剂的技术因具有快速、高效和简单等优点而受到广泛关注。然而,该技术存在超顺磁性吸附剂的回收过程过度依赖于高磁场和高磁场梯度的使用且难以放大的问题。为解决这一难题,本文将气泡对颗粒的表面作用力这种新力引入到磁分离过程中以期能显著降低磁分离过程对磁力的依赖,建立可高效用于重金属废水处理的气助超顺磁分离技术。研究内容主要包括以下三个方面:(1)制备了一种新的长链聚乙二醇修饰的Fe_3O_4超顺磁性纳米颗粒,该吸附剂对重金属Cr(VI),Pb(II),和Cu(II)离子的最大饱和吸附容量分别为:15.07 mg/g,21.27 mg/g,41.0 mg/g,在大约60 min内达到吸附平衡,获得了溶液pH值、吸附剂投加量、离子强度对其吸附性能的影响规律,证明了聚乙二醇的包覆使磁性纳米颗粒具有更好的耐酸性能。(2)以Fe_3O_4/PEG、Fe_3O_4/HA-Na和Fe_3O_4/PPy超顺磁性纳米颗粒分别用于去除Cu(II)、Pb(II)、Cr(VI)废水溶液为模拟体系,开展了气助磁分离用于从废水中高效回收吸附了重金属的磁性纳米颗粒的可行性研究,考察了气体流速、金属离子负载量、pH值、磁颗粒浓度、分离距离等因素对气助磁分离效率的影响。结果表明:气泡能显著加速磁分离过程,实现对磁性纳米颗粒的远距离高效捕获,可通过调节气速、离子强度和溶液pH值等实现过程的进一步强化。与单纯磁分离进行对比,气助磁分离具有更高效、可远距离捕获、过程强化可不依赖于磁力和对低浓度磁颗粒的回收更高效的优点,是一种有前景的易于放大的从稀溶液重金属废水中高效回收磁性纳米颗粒的方法。(3)通过对气泡和上述三种负载重金属磁性纳米颗粒的Zeta电位的测量,从气泡和颗粒间静电作用力的角度,考察了重金属负载量、pH值和离子强度对负载有重金属的磁颗粒和气泡间的静电作用力的影响规律,结合前期实验结果的验证,初步探讨和解析了上述三个参数对气助超顺磁分离过程的调控机理。
[Abstract]:Heavy metal pollutants have the characteristics of low concentration toxicity, persistent toxicity, non-degradability and accumulation into human body through the food chain, which will lead to serious environmental pollution. How to remove heavy metal pollutants from wastewater to eliminate environmental hazards is an important environmental problem to be solved. In recent years, the technology based on superparamagnetic adsorbent has attracted wide attention because of its advantages of rapidity, high efficiency and simplicity. However, the recovery process of superparamagnetic adsorbent is too dependent on the use of high magnetic field and high magnetic gradient and is difficult to amplify. In order to solve this problem, the new force of bubble acting on the surface of particles is introduced into the magnetic separation process in order to reduce the dependence of magnetic force on the magnetic separation process. A gas-assisted superparamagnetic separation technique for heavy metal wastewater treatment was established. A novel long chain polyethylene glycol modified Fe_3O_4 superparamagnetic nanoparticles were prepared in the following three aspects. The maximum saturated adsorption capacity of the adsorbent for the heavy metal CrVII-PbCII, and CuOII) is respectively: 15.07 mg / g ~ 21.27 mg / g ~ 41.0 mg / g, and the adsorption equilibrium is achieved in about 60 min. The effects of pH value, adsorbent dosage and ionic strength on the adsorption performance are obtained. It has been proved that the coating of polyethylene glycol makes magnetic nanoparticles have better acid resistance. The feasibility of gas assisted magnetic separation (GASM) for recovering high efficiency magnetic nanoparticles adsorbed heavy metals from wastewater was studied. The gas flow rate, metal ion loading amount, pH value and magnetic particle concentration were investigated. The effect of separation distance and other factors on the separation efficiency of gas-assisted magnetic separation. The results show that the bubble can accelerate the magnetic separation process significantly and achieve the long distance and high efficiency capture of the magnetic nanoparticles, which can be further strengthened by adjusting the gas velocity, ionic strength and pH value of the solution. Compared with pure magnetic separation, gas-assisted magnetic separation has the advantages of more efficient, long-range capture, process enhancement independent of magnetic force and more efficient recovery of low concentration magnetic particles. It is a promising and easy to amplify method for recovering magnetic nanoparticles efficiently from heavy metal wastewater of dilute solution by measuring the Zeta potential of bubbles and the three magnetic nanoparticles loaded with heavy metals. From the point of view of electrostatic force between bubbles and particles, the effects of heavy metal loading amount, pH value and ionic strength on the electrostatic force between magnetic particles loaded with heavy metals and between bubbles were investigated. The regulation mechanism of these three parameters on the gas-assisted superparamagnetic separation process is discussed and analyzed.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;TQ028.8

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