以葡萄糖为原料制备碳材料及其铀吸附性能研究

发布时间：2018-01-20 04:44

  本文关键词： 葡萄糖 水热碳化 催化剂 吸附 铀　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：铀矿冶、核燃料前段及乏燃料后处理废水中含有大量的铀,对其进行处理及回收废水中的铀是对有限的铀资源的充分利用,也将有效避免放射性废水对人类的危害及对生态环境的破坏。吸附法以经济、高效、操作简单等优点已经成为处理低浓度含铀废水及提取铀的优选方法。针对含铀废水的特殊性,研究开发具有抗辐射性及耐酸性能,且吸附容量大的新型吸附剂是吸附法处理放射性废水的重中之重。本研究以葡萄糖为主要原料,通过水热碳化、焙烧、KOH活化和酸化处理等方法制备了水热碳微球及多孔氧化碳吸附剂,系统研究了低温水热碳化工艺及催化剂Al Cl3对碳微球形貌及性能的影响,以及碳微球的形成机理;研究了KOH用量和酸处理方法对多孔碳形貌及性能的影响。同时,研究了水热碳微球及多孔氧化碳吸附剂对溶液中U(VI)的吸附特性和机理,探究了碳材料循环利用特性。结果表明:1、以葡萄糖为原料,Al Cl3为催化剂,采用水热碳化法在120~150℃温度范围合成制备了水热碳微球(HTC)。当Al Cl3用量为20 mol%、水热碳化温度为130℃,以及反应时间为20 h时,水热碳微球呈单一球形且光滑表面。微球的粒径分布为0.5~5.5μm,且表面拥有丰富的活性氧基团;碳微球内部存在有呋喃环结构,其在整个碳微球结构中所占的比例随温度升高而下降;经过焙烧的水热碳微球(HTC-COOH),表面的羧基官能团增加,吸附位点增加,有利于碳微球对U(VI)的吸附。2、焙烧后的碳微球(HTC-COOH)对U(VI)的最佳吸附条件是:环境温度为25℃、溶液p H值为4.5、初始浓度为140 mg·L-1、且吸附时间为22h。在此条件下,HTC-COOH碳微球对溶液中U(VI)的最大吸附量为163mg·g-1,吸附过程符合Langmuir等温吸附模型及准二级动力学模型。HTC-COOH碳微球对U(VI)的吸附主要发生在其外表面,且主要是碳微球上的羧基与U(VI)之间发生离子交换,其次还有羟基与U(VI)之间的相互作用。3、以葡萄糖和尿素为原料先合成葡萄糖-尿素树脂,再经管式气氛炉焙烧、KOH活化和酸处理,制备了多孔氧化碳(m-a-4-NC)。研究了m-a-4-NC对溶液中U(VI)的吸附特性,当溶液p H值为4.5,吸附时间为120 min时,m-a-4-NC对U(VI)的最大吸附量为397 mg·g-1;吸附过程符合准二级动力学模型和Langmuir等温吸附模型。多孔氧化碳材料对U(VI)的吸附主要为羧基与U(VI)之间的离子交换。4、采用FTIR、XPS、SEM及N2吸附-脱附等温线模型等对多孔氧化碳材料的微观形貌、化学结构及性能特性进行了表征。未经酸化处理的多孔碳(a-4-NC)含有丰富的开孔结构,经过酸化处理之后的m-a-4-NC材料的表面变得粗糙,但是材料内部的大孔及介孔结构依然存在,这有利于吸附U(VI)时液体的快速流动。
[Abstract]:There is a large amount of uranium in the waste water of uranium mining, nuclear fuel front and spent fuel reprocessing, and the treatment and recovery of uranium from waste water is the full utilization of limited uranium resources. It will also effectively avoid the harm of radioactive wastewater to human beings and ecological environment. The adsorption method is economical and efficient. The advantages of simple operation have become the optimal method for the treatment of low concentration wastewater containing uranium and the extraction of uranium. In view of the particularity of the wastewater containing uranium radiation resistance and acid resistance have been studied and developed. The new adsorbent with large adsorption capacity is the most important in the treatment of radioactive wastewater by adsorption. In this study, glucose was used as the main raw material and calcined by hydrothermal carbonization. Hydrothermal carbon microspheres and porous carbon oxide adsorbents were prepared by KOH activation and acidification. The effects of hydrothermal carbonization at low temperature and Al Cl3 catalyst on the morphology and properties of carbon microspheres were systematically studied. And the formation mechanism of carbon microspheres; The effects of KOH content and acid treatment method on the morphology and properties of porous carbon were studied. Meanwhile, the adsorption characteristics and mechanism of hydrothermal carbon microspheres and porous carbon oxide adsorbents for Utv I in solution were studied. The recycling characteristics of carbon materials were investigated. The results showed that: 1, with glucose as raw material, Al Cl3 was used as catalyst. Hydrothermal carbon microspheres (HTC) were synthesized by hydrothermal carbonization at a temperature range of 120,150 鈩，

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