硅胶杂化材料的制备及其吸附性能研究

发布时间：2018-05-16 04:30

本文选题：硅胶 + 硫脲　；参考：《郑州大学》2015年硕士论文

【摘要】：本文选用对金属离子有选择络合作用的,常用作汞离子掩蔽剂的硫脲(TU)作为有机修饰物,无机硅胶(Si O2)为载体,通过硅烷偶联剂固定法,将有机硫脲固载于无机硅胶表面,合成了无机硅胶杂化材料硫脲基硅胶(TU/Si O2)。首先利用氯丙基偶联剂对无机硅胶表面进行偶联反应,生成氯丙基硅胶(CP-Si O2),然后硫脲与氯丙基硅胶发生氯取代反应生成硫脲基硅胶。考察了合成条件对硫脲基硅胶制备反应的影响,最终确定合成条件为:以表面氯基含量为1.68mmol/g的CP-Si O2为基准,mCP-Si O2/g=5,mTU/g=2,mKI/g=0.6,VCH3CH2OH/m L=50,温度为348K,反应时间为24h。最终合成的产物硫脲基硅胶对汞离子有优良的吸附容量及吸附选择性。采用静态法研究TU/Si O2材料对Hg2+的静态吸附性能。考察了各静态吸附条件对吸附性能的影响,随着溶液的p H值增大,温度的升高及金属离子浓度的增大,TU/Si O2材料对Hg2+的吸附容量增大。用吸附模型对等温吸附过程进行拟合,结果表明TU/Si O2材料对Hg2+的吸附平衡符合Langmuir模型,即吸附过程为单分子层吸附过程;由Freundlich等温方程线性拟合得出的1/n介于0.1-0.5,表明TU/Si O2材料吸附Hg2+的是比较容易进行的。热力学数据ΔH00,ΔS00,ΔG00,说明该吸附过程是一个自发进行的吸热、固液界面趋于无序的过程,而|ΔH0||TΔS0|,表明该吸附过程主要由熵变控制。对静态吸附过程进行动力学模型拟合,结果表明可以用准二级动力学模型描述TU/Si O2对Hg2+的吸附过程。采用动态法研究TU/Si O2材料对Hg2+的动态吸附性能。对单组分动态吸附的研究结果表明,增大进液流量、Hg2+的浓度,都会减少穿透时间及耗竭时间,而降低进液流量、增大金属离子浓度有利于提高材料的饱和吸附容量。对汞锌双组分的研究结果表明,TU/Si O2材料对Hg2+有明显吸附选择性,Hg2+、Zn2+在吸附材料表面会同时发生竞争吸附和置换吸附,材料对Zn2+的穿透时间及耗竭时间明显小于对Hg2+的结果。对比单一汞组分与汞锌双组分动态吸附效果,Zn2+的存在对TU/Si O2材料吸附Hg2+的行为影响不显著。通过用Thomas模型、Yan模型对实验结果模拟分析,发现这两种模型都可以用来描述TU/Si O2材料对Hg2+的动态吸附过程。
[Abstract]:In this paper, thiourea (Tu), which has selective complexation to metal ions and is often used as masking agent for mercury ions, is used as organic modifier and inorganic silica gel Sio _ 2) as carrier. Organic thiourea is immobilized on the surface of inorganic silica gel by silane coupling agent fixation method. The inorganic silica gel hybrid material, thiourea based silica gel, was synthesized. The surface of inorganic silica gel was first coupled by chloropropyl coupling agent to form CP-SiO _ 2N, then thiourea reacted with chloropropyl silica gel to form thioureum-based silica gel. The effect of synthesis conditions on the preparation of thiourea based silica gel was investigated. The final conditions of synthesis were as follows: based on CP-Si O 2 with surface chloro content as 1.68mmol/g, mCP-Si O 2 / 5 mTU / g O 2 mKI / g 0. 6 and VCH 3CH 2O H / m L 50, temperature 348 K and reaction time 24 h. The final product thiourea-based silica gel has excellent adsorption capacity and selectivity for mercury ions. The static adsorption properties of TU/Si O 2 for Hg2 were studied by static method. The effects of various static adsorption conditions on the adsorption properties were investigated. With the increase of pH value of solution, the increase of temperature and the increase of metal ion concentration, the adsorption capacity of TU / Sio _ 2 to Hg2 was increased. The isothermal adsorption process was fitted with the adsorption model. The results showed that the adsorption equilibrium of TU/Si O 2 for Hg2 was in accordance with the Langmuir model, that is, the adsorption process was monolayer adsorption. The linear fitting of 1 / n from the Freundlich isothermal equation shows that the adsorption of Hg2 by TU/Si O _ 2 is easy. The thermodynamic data 螖 H _ (00), 螖 S _ (00), 螖 G _ (00) indicate that the adsorption process is a spontaneous endothermic process and the solid-liquid interface tends to be disordered, while 螖 H _ (0T) 螖 S _ (0) indicates that the adsorption process is mainly controlled by entropy variation. The kinetic model fitting the static adsorption process shows that the quasi-second-order kinetic model can be used to describe the adsorption process of Hg2 by TU/Si O _ 2. The dynamic adsorption properties of TU/Si O 2 for Hg2 were studied by dynamic method. The results of single-component dynamic adsorption show that increasing the concentration of Hg2 can reduce the penetration time and depletion time, but decrease the flow rate and increase the concentration of metal ions to increase the saturated adsorption capacity of the material. The results of the study on the two-component of Hg / Zn _ (2) show that the adsorption selectivity of Hg2 on Hg2 is obvious and the adsorption of Hg ~ (2 +) ~ (2 +) Zn _ (2) on the surface of Hg2 / Zn _ (2) is competitive adsorption and displacement adsorption at the same time. The breakthrough time and depletion time of the material to Zn2 is obviously smaller than that of Hg2. The effect of Zn _ 2 on the adsorption of Hg2 by TU/Si O _ 2 was not significant compared with the dynamic adsorption effect of single mercury component and two-component mercury zinc. By using the Thomas model and Yan model to simulate the experimental results, it is found that both models can be used to describe the dynamic adsorption process of Hg2 on TU/Si O2 materials.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;TQ424

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