沥青基多孔炭的制备及其对染料吸附性能的研究

发布时间：2018-05-10 22:20

本文选题：多孔炭 + 模板　；参考：《安徽工业大学》2017年硕士论文

【摘要】：吸附法在处理印染废水中占有重要地位,吸附剂则是吸附技术的核心。多孔炭因其具有高的比表面积、发达的孔隙结构、丰富的表面官能团等优点而引起人们的探究兴趣,而多孔炭的孔径结构的设计与调控是提高其吸附性能的关键所在。本文针对分子尺寸较大的染料,选择煤沥青为碳源、分别采用合成的镁铝水滑石和MgO为模板耦合KOH活化,通过控制模板与碳源的质量比及活化温度分别制备了中孔炭和分级多孔炭,并对分级多孔炭进行负载金属离子改性。借助场发射扫描电镜(FESEM),透射电镜(TEM)、氮吸附等手段对多孔炭材料的物理结构和表面形态进行了表征,并考察了其对染料的吸附性能,其主要结果如下:(1)以煤沥青为碳源,合成的镁铝水滑石为模板耦合氢氧化钾活化,采用常规加热的活化方式,制得具有片层状结构的中孔炭。当模板与碳源的质量比为4时,制得中孔炭MPC_4,其比表面积、平均孔径和比孔容分别为936 m~2/g、7.37 nm和1.73 cm~3/g。作为吸附剂,所制备的MPC_4对酸性橙74、茜素绿和碱蓝6B均有较好的吸附性能,吸附等温线研究表明,Langmuir模型能更好的描述MPC_4对茜素绿的吸附过程,而对酸性橙74和碱蓝6B的吸附过程,则适用于Freundich模型。动力学研究表明,MPC_4对酸性橙74和碱蓝6B的吸附过程符合拟二级动力学方程,对茜素绿的吸附过程符合拟一级动力学方程。由于所制的MPC_4平均孔径较大,难以和染料形成较强的色散力,其对染料的吸附性能低于比表面积为1400 m~2/g的商品炭。(2)以煤沥青为碳源,纳米MgO为模板耦合KOH活化,改变模板和碳源的质量比和活化终温制备具有中空球形结构的分级多孔炭。当煤沥青和纳米MgO质量分别为2和19 g,活化终温为900℃,所制得的HPC_(2-19-900)的比表面积、比孔容和平均孔径分别为2292 m~2/g、2.05 cm~3/g和3.57 nm。由于比表面积的提高,HPC_(2-19-900)对酸性橙74、茜素绿和碱蓝染料都表现出优异的吸附性能。当三种染料的平衡浓度为170mg/L左右时,HPC_(2-19-900)对酸性橙74、茜素绿和碱蓝的平衡吸附量分别为3097、1373和4169 mg/g。对吸附等温线进行拟合发现,Freundich模型能更好的描述HPC_(2-19-900)对三种染料的吸附等温线;动力学研究表明,HPC_(2-19-900)对三种染料的吸附动力学过程符合拟二级动力学方程。由于分级多孔炭中含有大量的大微孔和小中孔,这些孔能和染料之间形成强的色散力,HPC_(2-19-900)对三种染料的吸附性能均高于商品炭,表明制备的分级多孔炭是性能优异的染料吸附剂。(3)对HPC_(2-19-900)进行负载金属离子改性,考察不同金属离子负载对其染料吸附性能的影响。尽管金属离子的负载导致多孔炭比表面积下降,但其表面也引入了对染料具有较强作用力的新的吸附活性位。由于表面含有大量高度分散的Zn(Ⅱ),在较低浓度下,Zn(Ⅱ)/HPC对酸性橙74、茜素绿和碱蓝6B都表现出优异的吸附性能,表明Zn(Ⅱ)/HPC能深度脱除废水中的染料分子。同样由于产生新的吸附活性位,Cu(Ⅱ)/HPC对酸性橙74的吸附量较初始多孔炭也有明显的提高;对于分子尺寸较大的茜素绿,与初始炭相比,Fe(Ⅲ)/HPC对其吸附性能也有一定程度的提高。对吸附等温线进行拟合,发现Langmuir模型能更好的描述Zn(Ⅱ)/HPC对三种染料的吸附过程,而Freundich模型更适用于分别描述Cu(Ⅱ)/HPC对酸性橙74和Fe(Ⅲ)/HPC对茜素绿的吸附过程。吸附动力学研究表明,Zn(Ⅱ)/HPC对三种染料,Cu(Ⅱ)/HPC对酸性橙74的吸附动力学过程均符合拟二级动力学方程,而Fe(Ⅲ)/HPC对茜素绿的动力学过程符合拟一级动力学方程。
[Abstract]:Adsorption method plays an important role in the treatment of printing and dyeing wastewater. Adsorbents are the core of adsorption technology. Porous carbon has the advantages of high specific surface area, developed pore structure and rich surface functional groups, and the design and regulation of pore structure of porous carbon is the key to improve its adsorption performance. In this paper, the coal bitumen was selected as the carbon source for the dye with large molecular size, and the synthesized magnesia aluminum hydrotalcite and MgO were used as the template coupling KOH activation. The mesoporous carbon and the graded porous carbon were prepared by controlling the mass ratio and the activation temperature of the carbon source, and the graded porous carbon was loaded with metal ions. The physical structure and surface morphology of the porous carbon materials were characterized by scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and nitrogen adsorption. The adsorption properties of the dyes were investigated. The main results were as follows: (1) the synthesized magnesia aluminum hydrotalcite was activated by the template coupled with potassium hydroxide, and the conventional heating method was used. The mesoporous carbon with lamellar structure was prepared. When the mass ratio of the template and carbon source was 4, the mesoporous carbon MPC_4 was prepared. The specific surface area, the average pore size and the specific pore volume were 936 m~2/g, 7.37 nm and 1.73 cm~3/g. respectively. The prepared MPC_4 had better adsorption properties for Acid Orange 74, alizarin green and Alkali Blue 6B, and the adsorption isotherm study It shows that the Langmuir model can better describe the adsorption process of MPC_4 to alizarin green, while the adsorption process for acid orange 74 and Alkali Blue 6B is suitable for Freundich model. Kinetics study shows that the adsorption process of MPC_4 to acid orange 74 and Alkali Blue 6B is in accordance with the pseudo two kinetic equation, and the adsorption process of Alizarin green is in accordance with the pseudo first order kinetic equation. Because of the larger average pore size of the MPC_4, it is difficult to form a strong dispersion force with the dye, and the adsorption performance of the dye is lower than that of the commercial carbon with a specific surface area of 1400 m~2/g. (2) the coal tar is used as the carbon source and the nano MgO is activated by the template coupling KOH, and the mass ratio of the template and carbon source and the final temperature of the activation are used to prepare the hollow spherical structure. Porous carbon. When the mass of coal tar pitch and nanoscale MgO are 2 and 19 g respectively, the final activation temperature is 900 C, the specific surface area of HPC_ (2-19-900) is 2292 m~2/g, 2.05 cm~3/g and 3.57 nm., respectively, with the increase of specific surface area, HPC_ (2-19-900) shows excellent adsorbability to acid orange 74, alizarin green and alkali blue dye. When the equilibrium concentration of three dyes is about 170mg/L, the equilibrium adsorption of HPC_ (2-19-900) to acid orange 74, alizarin green and alkali blue are 30971373 and 4169 mg/g., respectively. The Freundich model can better describe the adsorption isotherm of HPC_ (2-19-900) to three dyes; kinetics study shows HPC_ (2-19). -900) the adsorption kinetics of the three dyes accorded with the pseudo two kinetic equation. Due to the large number of micropores and small mesopore in the porous carbon, these pores could form a strong dispersion force between the dyes and the dye, and the adsorption properties of the three dyes were higher than that of the commercial carbon, indicating that the porous carbon prepared by the HPC_ (2-19-900) was an excellent dye dyeing. (3) (3) the modification of metal ions was carried out on HPC_ (2-19-900), and the effect of different metal ion loads on the adsorption properties of the dye was investigated. Although the load of metal ions resulted in a decrease in the specific surface area of the porous carbon, the surface also introduced a new adsorption active site with strong force on the dye. Dispersed Zn (II), at lower concentration, Zn (II) /HPC showed excellent adsorption properties for acid orange 74, alizarin green and Alkali Blue 6B, indicating that Zn (II) /HPC can remove dye molecules in the wastewater. The adsorption capacity of Cu (II) /HPC to acid orange 74 is also significantly higher than that of initial porous carbon due to the production of new adsorptive active sites. The large size alizarin green, compared with the initial carbon, Fe (III) /HPC also improved its adsorption properties to a certain extent. The adsorption isotherm was fitted, and the Langmuir model could better describe the adsorption process of Zn (II) /HPC to three dyes, and the Freundich model was more suitable for describing Cu (II) /HPC to acid orange 74 and Fe (III) /HPC pairs respectively. The adsorption kinetics of Alizarin green shows that the adsorption kinetics of Zn (II) /HPC on three dyes and Cu (II) /HPC for acid orange 74 conforms to the pseudo two kinetic equation, and the kinetic process of Fe (III) /HPC for Alizarin green is in accordance with the pseudo first order kinetic equation.

【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ424;X791

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