偕胺肟化碳纳米管的制备及其对铀和铅的吸附研究

发布时间：2018-04-24 01:10

  本文选题：偕胺肟化碳纳米管 + 铀　； 参考：《南华大学》2015年硕士论文

【摘要】：由于工农业的迅速发展,导致排放入水体中的重金属含量越来越高,已经达到了不可忽视的地步。由于铀元素具有放射性和化学毒性双重危害,如何有效的处理废水中的铀污染已经引起了科研人员的广泛关注。对于重金属的另一种元素铅,与铀元素相比,虽然没有放射毒性,但铅离子的潜在毒性(如致癌、致畸、致突变)也是不能忽视的,尤其是随着近年来铅污染事件的频繁发生,使人们意识到对废水中铅污染的治理也迫在眉睫。本文以多壁碳纳米管为原料,先进行羧基化、酰氯化、酰胺化,然后经过氰基化、胺肟化得到偕胺肟化碳纳米管(AO-MWNTs)。对所得产物进行红外光谱、扫描电镜、透射电镜等表征。通过静态实验,研究在不同的p H值、振荡时间、温度、投加量等条件下研究改性碳纳米管对铀和铅的吸附性能,并对吸附过程进行动力学和热力学分析,借助SEM、FTIR等仪器分析手段探讨其吸附机理。实验结果表明:当p H为5时,改性前碳纳米管(raw-MWNTs)和AO-MWNTs对铀的吸附效果最好,羧基化碳纳米管(COOH-MWNTs)和氨基化碳纳米管(NH2-MWNTs)对铀的最佳吸附p H值为6。随着吸附时间和铀初始浓度的不断增大,这四种吸附材料对铀的吸附容量都逐渐增大,这四种吸附材料对铀的吸附能力从大到小依次为:AO-MWNTsNH2-MWNTsCOOH-MWNTsraw-MWNTs,而随着吸附剂投加量的不断增大,吸附容量不断降低。在CO32-、SO42-阴离子共存的情况下,对偕胺肟化碳纳米管吸附铀的影响较大,而阳离子Zn2+、Pb2+共存的情况下对该吸附效果的影响较小。动力学拟合结果显示:这四种材料对铀的吸附都符合准二级吸附动力学模型,热力学模型符合Langmuir模型。AO-MWNTs在铅初始浓度为10mg/L、温度为25℃、p H=6、吸附剂投加量为0.025g时,其对铅离子的吸附容量能达到17.24mg/g。而未改性的碳纳米管在同等条件下对铅的吸附容量只能达到8.3mg/g。AO-MWNTs对铅的吸附过程在动力学方面符合准二级动力学模型,在热力学方面Freundlich能更好的描述该过程。
[Abstract]:Due to the rapid development of industry and agriculture, the heavy metal content discharged into the water becomes higher and higher, which can not be ignored. Because uranium has the dual harm of radioactivity and chemical toxicity, how to effectively treat uranium pollution in waste water has attracted extensive attention of researchers. For lead, another element of heavy metals, although it has no radiotoxicity compared with uranium, the potential toxicity of lead ions (such as carcinogenesis, teratogenicity, mutagenicity) cannot be ignored, especially with the frequent occurrence of lead contamination in recent years. To make people aware of the treatment of lead pollution in wastewater is also imminent. In this paper, multiwalled carbon nanotubes (MCNTs) were prepared by carboxylation, acylation, amidation, and then cyanoylation, amidation to obtain AO-MWNTsO. The products were characterized by IR, SEM and TEM. The adsorption properties of modified carbon nanotubes for uranium and lead under different pH values, oscillating time, temperature and dosage were studied by static experiments, and the kinetics and thermodynamics of the adsorption process were analyzed. The adsorption mechanism was discussed by means of SEMX FTIR and other instruments. The experimental results show that when pH is 5, the adsorption of uranium by modified pre-carbon nanotubes (PNTs) and AO-MWNTs is the best. The best adsorption pH value for uranium by COOH-MWNTs and NH2-MWNTs is 6. With the increasing of the adsorption time and the initial concentration of uranium, the adsorption capacity of the four adsorbents for uranium gradually increased. The adsorption capacity of the four adsorbents for uranium was in the order of: AO-MWNTsNH2-MWNTsCOOH-MWNTsraw-MWNTswith the increasing amount of adsorbent. The adsorption capacity is decreasing. The adsorption of uranium by amidoxime carbon nanotubes (CNTs) is greatly affected by the coexistence of CO32-OSO42-anions, while the adsorption of uranium by cationic Zn2 Pb2 has little effect on the adsorption. The kinetic fitting results show that the adsorption of uranium by these four materials is in accordance with the quasi-second-order adsorption kinetic model, and the thermodynamic model accords with the Langmuir model .AO-MWNTs when the initial concentration of lead is 10 mg / L, the temperature is 25 鈩，

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