【作者】 范桥辉；

【导师】 吴王锁；

【作者基本信息】 兰州大学 ， 无机化学， 2008， 硕士

【摘要】 本论文采用静态批式吸附法与微观表征(如FTIR、XRD、XPS等技术)相结合研究凹凸棒石粘土与Ni(Ⅱ)、Pb(Ⅱ)、Eu(Ⅲ)、Th(Ⅳ)作用机理和模式。本论文共分十章。第一章简要介绍了论文的选题背景、依据以及研究的基本内容和总体方案。第二章简要回顾了与固-液界面吸附相关的一些基本概念和理论。第三章介绍了本工作的详细实验方法。第四章使用FTIR、XRD、XPS和酸碱滴定分别对凹凸棒石的结构、主要元素组成、官能团和表面“吸附位”进行了详细的表征,得出其本征酸度常数和“表面位”浓度等相关参数。第五、六章分别对Ni(Ⅱ)在Na-凹凸棒石粘土、柠檬酸铵改性凹凸棒石粘土上吸附进行了详细研究。结果表明Ni(Ⅱ)的凹凸棒石上的吸附作用受pH值、离子强度影响明显;在pH＜8时,离子强度的影响强烈;而当pH＞8时,Ni(Ⅱ)的吸附不受离子强度的影响。吸附一解吸实验研究表明当pH=6.0时,Ni(Ⅱ)的吸附是可逆的。pH＜8时,离交换或外部络合是Ni(Ⅱ)在钠基凹凸棒石上吸附主要的机理;而pH＞8时,主要是内部络合模式。腐殖酸的影响表明FA和HA对Ni(Ⅱ)的吸附均有一定抑制作用。温度影响表明温度升高有利于Ni(Ⅱ)在钠基凹凸棒石表面上吸附,且该吸附是一吸热、自发的过程。柠檬酸铵改性凹凸棒石后明显改善或提高了对金属离子Ni(Ⅱ)的吸附作用。在低pH值条件下受外来干扰离子影响明显,在较高pH值条件下却几乎不受外来离子干扰;柠檬酸铵改性凹凸棒石粘土提高了对Ni(Ⅱ)的吸附效果,但是高温处理的凹凸棒石(500℃)由于其结构遭到破坏而使吸附能力减弱。第七、八章分别讨论了Pb(Ⅱ)在高温活化凹凸棒石上吸附;Eu(Ⅲ)在Na-凹凸棒石上吸附研究;并采用FITEQL对Pb(Ⅱ)、Eu(Ⅲ)的吸附进行表面络合拟合,结果表明在低pH值下主要是“弱位”(=WOH)与金属离子Pb(Ⅱ)、Eu(Ⅲ)发生络合作用;在高pH值下则主要是“强位”(=SO~-)与金属离子Pb(Ⅱ)、Eu(Ⅲ)发生络合作用;且离子强度对吸附机理有一定影响。实验结果表明,HA对Eu(Ⅲ)的吸附有明显的影响:在pH＜4时,腐殖酸HS对吸附影响不明显,当4＜pH＜6时,HS开始抑制Eu(Ⅲ)在Na-凹凸棒石上的吸附,在pH6-8时,吸附作用达到最低,当pH＞8是,吸附又开始随pH值升高而逐渐增大。第九章研究了高温活化凹凸棒石对Th(Ⅳ)的吸附性能。pH值对Th(Ⅳ)在凹凸棒石粘土上的吸附有显著影响,而离子强度对吸附的影响却相对较弱;Th(Ⅳ)凹凸棒石表面主要发生内部络合,腐殖酸FA和HA对吸附有很大的促进作用;腐殖酸的加入次序对Th(Ⅳ)在凹凸棒石上吸附没有明显影响;另外提高反应温度有利于Th(Ⅳ)在高温活化凹凸棒石粘土上的吸附,实验结果表明Th(Ⅳ)在凹凸棒上吸附是自发吸热的过程;最后,高温活化凹凸棒石粘土对Th(Ⅳ)的吸附是不可逆的过程;但是在FA存在的吸附体系中,Th(Ⅳ)的吸附几乎是一个可逆的过程。第十章对本论文的研究结果进行总结,并对以后的研究提出一些设想。实验结果表明,凹凸棒石对重金属离子及放射性核素具有较强的吸附能力,其柠檬酸铵的有机改性凹凸棒石粘土对吸附高浓度重金属离子方面具有优势。一般凹凸棒石对Ni(Ⅱ)、Pb(Ⅱ)、Eu(Ⅲ)、Tb(Ⅳ)的吸附率随体系pH的增大而提高,随体系离子强度的增大而降低。土壤提取物FA/HA对凹凸棒石吸附性能的影响随金属离子种类的不同而不同,在不同的pH区段影响不同。重金属离子和放射性核素在凹凸棒石上的吸附热力学参数计算结果表明,在本实验条件下吸附是个自发的、反应限度很大、放热的过程。表面络合和离子交换是重金属离子和放射性核素在凹凸棒石上的主要吸附机理。更多还原

【Abstract】 In this paper, the batch adsorption experiment and combining with micro-characterizing (such as Fourier Transform infrared sorption (FTIR), X-ray photoelectron spectroscopy(XPS), and XRD so on) were used to study the adsorption of Ni(II), Pb(II), Eu(III) and Th(IV) on attapulgite. The dissertation was divided into ten chapters.In the first chapter, the study background, basic content and sketch of experimental scheme were introduced in brief.In the second and third chapter, some basic concepts and principles related to adsorption on solid-liquid surface were described, and the methods, which were used in this paper, were introduced in detail.In the fourth chapter, the structure, elements of composition, function groups, and the adsorption sites of attapulgite was characterized by XPS, XRD, FTIR and Acid-Base titration, respectively; the relative parameters of acid constants, sites density and so on were calculated.In the fifth and sixth chapter, the adsorption of Ni(II) on Na-attapulgite and ACT-attapulgite were investigated, respectively; it indicated that the adsorption of Ni(II) was influenced strongly by pH and ionic strength. Compared with Na-attapulgite, the adsorption capacity of ACT-attapulgite to Ni(II) was improved significantly.In the seventh and eighth chapter, the adsorption of Pb(II) onto activated attapulgite and Eu(III) onto Na-attapulgite were studied respectively, and the FITEQL code and Surface Complexation Model(SCM) were used to simulated the adsorption data of Pb(II) and Eu(III) onto attapulgite; and found the main adsorption species of Pb(II) and Eu(III) onto attapulgite was weak sites(=WOH) at low pH values, however, was strong sites(=SO~-) at higher pH values. In addition, the adsorption species was influenced by ionic strength weakly.In the ninth chapter, the adsorption of Th(IV) on activated attapulgite was investigated. In the tenth chapter, the results were summarized and future study proposals were put forward.The results of this paper show that attapulgite has good adsorption ability to heavy metal ions and radionuclides, and its organic modified sample, i.e., ACT-attapulgite, has advantage in treating high concentration of heavy metal ions than attapulgite. The adsorption of Ni(II), Pb(II), Eu(III) and Th(IV) increased with increasing pH and decreasing ionic strength. The influence of soil HA/FA on adsorption of heavy metal ion and radiounclides varied with different typical of cations, and different effects of HA/FA on cations adsorption were also found at different pH values. The thermodynamic parameters (i.e.;△H~0,△S~0, and△G~0) of the heavy metals and radionuclides adsorption onto attapulgite were calculated from the temperature dependence, and the results suggested that the adsorption reaction was spontaneous and exothermic with a high affinity. The adsorption mechanism was interpreted from the batch and spectroscopic results, and indicated that surface complexation model and cation competition exchange were considered as the main mechanism更多还原