粉煤灰螯合复合材料的制备及性能研究

发布时间：2018-06-18 03:20

本文选题：粉煤灰 + 螯合吸附　；参考：《西安科技大学》2017年硕士论文

【摘要】：随着我国工业的迅速发展,重金属废水的污染问题较为严峻。目前比较常用的重金属离子处置的方法有吸附法、化学沉淀法等。本文以粉煤灰、硫脲、戊二醛等为原料制备出一种新型的粉煤灰螯合复合材料。粉煤灰作为一种废弃物,廉价易得,因此该螯合复合材料的制备具有一定的环保价值和经济价值。由于粉煤灰粒度较小,因此不用进行预处理,可直接通过KH550对其表面改性并将硫脲接枝到粉煤灰表面,然后加入交联剂使其交联成型为吸附性能较好且具有一定强度的螯合复合材料。在接枝阶段,本文主要探究了偶联剂和螯合剂的种类及用量对最终的螯合复合材料吸附性能的影响;在交联的阶段,我们主要研究的因素有交联剂种类及用量;在整个反应的过程中我们探究的主要条件为反应的温度。最终通过螯合复合材料对Ni2+的吸附量来确定出终产物的最佳合成条件。用最佳条件下制备的螯合复合材料分别对重金属离子Ni2+、Cr6+进行吸附实验,并绘制吸附动力学和热力学曲线。结果表明:实验中偶联剂选用KH550时,终产物对Ni2+的吸附效果较好,其最佳的用量为0.3g;接枝螯合剂选取硫脲时,终产物对Ni2+的吸附效果较好,其最佳的用量为0.1g;交联剂选用戊二醛时,终产物的机械强度和吸附量都明显强于环氧氯丙烷;实验过程反应的最佳温度为313K。在最佳反应条件下,螯合复合材料对Ni2+、Cr6+的吸附量分别为38.76 mg/g,15.27mg/g,且其对重金属离子的吸附性能更加符合Lagergren二级反应吸附动力学方程及Freundlich的等温模型。通过SEM、XRD、FTIR、BET等手段对产物进行表征,扫描电镜结果表明,终产物与粉煤灰相比,形成了明显的网状大分子结构,因此其具有一定的机械强度,同时孔隙也较多,可保证其良好的吸附效果;红外结果表明硫脲被成功地接枝在了粉煤灰上,且戊二醛对其交联效果良好。通过BET分析可知,不同产物之间比表面积及孔容的变化说明了粉煤灰螯合复合材料对重金属离子不仅发生了吸附作用,而且发生了一定的螯合作用,实现了将粉煤灰的多孔结构与螯合剂硫脲对重金属离子螯合作用相结合的初衷。
[Abstract]:With the rapid development of industry in China, the pollution of heavy metal wastewater is more serious. At present, the commonly used methods of heavy metal ion disposal are adsorption method, chemical precipitation method and so on. In this paper, a new type of fly ash chelating composite was prepared by using fly ash, thiourea and glutaraldehyde as raw materials. As a kind of waste, fly ash is cheap and easy to obtain, so the preparation of the chelate composite has certain environmental and economic value. Because the particle size of fly ash is small, the surface of fly ash can be modified directly by KH550 without pretreatment, and thiourea can be grafted onto the surface of fly ash. Then the crosslinking agent was added to form the chelating composite with good adsorption property and certain strength. In the stage of grafting, the effects of the types and contents of coupling agents and chelating agents on the adsorption properties of the final chelating composites were investigated, while in the crosslinking stage, the main factors studied were the kinds and amounts of crosslinking agents. The main condition we explore throughout the reaction is the temperature of the reaction. Finally, the optimum synthesis conditions of the final product were determined by the adsorption amount of Ni _ 2 on the chelating composite. The adsorption experiments of heavy metal ion Ni2 + Cr6 were carried out by chelating composites prepared under the optimum conditions, and the adsorption kinetics and thermodynamic curves were plotted. The results showed that when the coupling agent KH550 was used, the adsorption effect of Ni2 on the final product was better, and the optimum dosage was 0.3 g, and when the grafting chelating agent was selected, the adsorption effect of the final product on Ni2 was better. When glutaraldehyde was used as crosslinking agent, the mechanical strength and adsorption capacity of the final product were obviously stronger than that of epichlorohydrin, and the optimum reaction temperature was 313K. Under the optimum reaction conditions, the adsorption capacity of Ni _ 2 / C _ (6) was 38.76 mg / g / g and 15.27 mg / g, respectively, and its adsorption performance for heavy metal ions was more in accordance with Lagergren second-order reaction adsorption kinetic equation and Freundlich's isothermal model. The products were characterized by means of SEMS-XRDX FTIRI-BET. The SEM results showed that the final product formed an obvious reticular macromolecule structure compared with fly ash, so it had a certain mechanical strength and a large number of pores. The IR results showed that thiourea was successfully grafted on fly ash and glutaraldehyde had good crosslinking effect. According to BET analysis, the change of specific surface area and pore volume between different products indicates that fly ash chelate composite not only adsorbs heavy metal ions, but also chelates them to a certain extent. The original intention of combining the porous structure of fly ash with chelating agent thiourea on heavy metal ion chelation was realized.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332;X703

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