活性碳纤维的低成本制备及其在染料污水净化中的应用

发布时间：2018-09-18 13:58

【摘要】：许多有机染料广泛应用于纺织、造纸、印刷、涂料、橡胶、食品等行业。存在于水体中的染料,即使很小的浓度也会对人类的健康和生存环境带来严重的危害。因此,如何有效的处理染料污水越来越受到人们的关注。本研究中,通过化学和物理方法对不同的前躯体处理得到不同的活性碳纤维材料,得到的活性碳纤维材料通过X射线衍射(XRD)、透射电子显微镜(TEM)、傅立叶红外光谱(FT-IR)、扫描电子显微镜(SEM)和氮气脱附吸附仪进行表征,并探究其对有机染料的吸附性能。以氨三乙酸铁(Fe-NTA)为前驱体合成纳米粒子组装的活性介孔碳纳米纤维(MCNFs),并首次应用于甲基橙(MO)和亚甲基蓝(MB)的吸附。合成的材料具有纤维形貌(直径约为150nm)、孔径为3-4nm、比表面积为392.3 m2 g-1。吸附实验讨论了pH对两种染料吸附结果的影响,当pH值为7.0时,MCNFs对亚甲基蓝和甲基橙的吸附量达到最大分别为137.25 mg g-1与110.99 mg g-1。考虑到MCNFs材料比表面积较小,为此采用Ni-NTA为前躯体,通过密闭煅烧合成了纳米球组装的碳纳米纤维(NC-1),进一步通过酸浸处理得到空心纳米球组装的碳纳米纤维(NC-2)。NC-2的比表面积达到422.3 m2 g-1,对MB的吸附量增加到147.23 mg g-1。利用动力学和等温吸附模型对MCNFs和NC-2对MB的吸附数据进行拟合,结果表明Lagergren准二级动力学模型和Langmuir热力学模型更符合实验结果。MCNFs和NC-2虽然对MB具有良好的吸附性能但用于制备这些前躯体的原料价格相对较高,并且合成过程较为繁琐。因此,我们以棉花和蒲苇花穗废弃物为原料,制备活性碳纤维材料(ACFs)。通过水热碳化和硫酸修饰对棉花废弃物进行处理得到活性碳纤维,并研究其对MB的性能。通过改变溶液的初始pH、无机盐浓度、温度和吸附剂用量等参数,对这两种吸附剂的最佳吸附条件进行探讨。研究表明ACFs对MB的吸附量在pH值为7时达到最大,随着Ca2+和Na+的浓度的增加而减小。等温吸附结果表明,其对MB的平衡吸附量在298、308、318K情况下依次为594.3 mg g-1、643.3 mg g-1和697.1 mg g-1,表明高温有利于吸附进行。采用蒲苇花穗(CSFS)为原料,在500 o C条件下密闭煅烧制备蒲苇花穗碳纤维材料(CSCF)。SEM研究结果表明,煅烧前后的CSCF的纤维形貌没有发生明显的断裂、凝结等现象。分别采用Langmuir、Freundlich、Temkin、Dubinin-Radushkevich(D-R)和Harkins-Jura(H-J)等温吸附模型对实验结果进行拟合,结果表明在四种温度下Langmuir拟合的相关因子R2均大于0.96,吸附容量达到110.2 mg g-1,因此Langmuir模型能够更好的模拟吸附过程。对两种吸附剂的热力学参数和吸附活化能计算结果可知(ΔGθ0、ΔHθ0、ΔSθ0)说明两种吸附剂的吸附过程是吸热、熵增加、自发的过程。
[Abstract]:Many organic dyes are widely used in textile, papermaking, printing, coating, rubber, food and other industries. Dyes existing in water, even at a small concentration, can cause serious harm to human health and living environment. Therefore, how to effectively treat dye wastewater has attracted more and more attention. METHODS Different activated carbon fibers were prepared from different precursors and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and nitrogen desorption adsorbent. Their adsorption properties for organic dyes were investigated. Active mesoporous carbon nanofibers (MCNFs) assembled by nanoparticles were synthesized by ferric acid (Fe-NTA) as precursor and first applied to the adsorption of methyl orange (MO) and methylene blue (MB). The synthesized materials have fiber morphology (diameter is about 150 nm), pore size is 3-4 nm, and specific surface area is 392.3 M2 g-1. The adsorption experiment discussed the adsorption results of pH on the two dyes. When the pH value was 7.0, the adsorption capacity of MCNFs to methylene blue and methyl orange reached 137.25 mg g-1 and 110.99 mg g-1, respectively. The specific surface area of carbon nanofibers (NC-2). NC-2 assembled by rice balls reached 422.3 M2 g-1, and the adsorption capacity of MB increased to 147.23 mg g-1. The adsorption data of MCNFs and NC-2 on MB were fitted by kinetic and isothermal adsorption models. The results showed that Lagergren quasi-second-order kinetic model and Langmuir thermodynamic model were more consistent with the experimental results. Activated carbon fiber materials (ACFs) were prepared from cotton and cattail reed spike wastes. The cotton wastes were treated by hydrothermal carbonization and sulfuric acid modification to obtain activity. Carbon fibers and their properties for MB were studied. The optimum adsorption conditions of the two adsorbents were discussed by changing the initial pH of the solution, the concentration of inorganic salts, temperature and the dosage of adsorbents. The equilibrium adsorption capacity for MB was 594.3 mg g-1,643.3 mg g-1 and 697.1 mg g-1 at 298,308 and 318 K respectively, indicating that high temperature was favorable for adsorption. Langmuir, Freundlich, Temkin, Dubinin-Radushkevich (D-R) and Harkins-Jura (H-J) isothermal adsorption models were used to fit the experimental results. The results showed that the Langmuir fitting correlation factor R2 was greater than 0.96 and the adsorption capacity reached 110.2 mg g-1 at the four temperatures. The thermodynamic parameters and adsorption activation energies of the two adsorbents (_G_0, _H_0, _S_0) show that the adsorption processes of the two adsorbents are endothermic, entropy increasing and spontaneous.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X703;TQ342.742

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