【作者】 彭国文；

【导师】 丁德馨；

【作者基本信息】 中南大学 ， 矿业工程， 2014， 博士

【摘要】 摘要：铀作为核燃料的主要成分,又是国防建设所必需的战略物质。为了满足核能快速发展和国防建设(核军工)的需求,仍然需要加大对铀矿资源的开采和选冶力度。然而,在铀矿资源开采和选冶过程中产生大量的含铀废水,将改变铀矿厂周围环境的本底辐射而致使物种基因畸变,对人类的生存和社会发展将构成潜在威胁,也将给人们身体健康和国家经济发展造成不利影响。因此,寻求吸附性能好、再生能力强和制备成本低的新型功能化吸附剂,显得十分重要。本论文基于铀酰离子特殊的空间配位结构的特点,构筑了一系列具有环境友好、吸附性能好、能重复利用的新型功能化吸附剂材料,并借助红外光谱(FTIR).扫描电镜(SEM)、X射线粉末衍射(XRD)和N2吸附-脱附实验等手段对所得的各种吸附剂进行了表征研究。以铀矿冶模拟含铀废水作为研究对象,利用静态吸附试验法进行了一系列含铀废水的吸附实验,考察了各种影响因素对吸附剂吸附铀的性能影响,并对吸附实验结果采用吸附动／热力学模型和等温线模型进行了分析和讨论,取得了较好的研究成果。论文的主要研究内容及结论如下：(1)提出了一种胱氨酸化学修饰啤酒酵母菌SC的新方法,构筑了一种新型的功能化生物吸附剂MSC。通过静态吸附试验法分别研究了SC和MSC对铀的吸附特性。结果发现,SC和MSC在pH值均为6.0时达到最大铀吸附量,MSC的最大吸附量q∞是SC的6.5倍。动力学研究发现SC和MSC吸附铀在1.0h就完成了80%的吸附量,在1.5h左右均可达到吸附平衡,而且准二级反应动力学模型能更好的描述了SC和MSC对铀的吸附过程。同时,Langmuir和Freundlich等温线模型能够描述SC和MSC吸附铀的行为,这一结果说明此吸附过程是单层覆盖和多层吸附相结合的。通过对SC和MSC解吸实验,发现SC和MSC均具有较好的再生性能,进行8次吸附解吸后吸附能力没有下降明显,说明吸附剂SC和MSC可以多次重复利用。(2)研究了新型环保且经济的纳米Fe304粒子制备方法,并提出了纳米Fe304粒子表面功能化改性的新方法。采用静态吸附法对比研究了纳米Fe304粒子和表面氨基功能化磁性吸附剂Fe3O4-NH2对铀的吸附特性。结果显示,纳米Fe3O4粒子和Fe3O4-NH2纳米颗粒吸附铀的最佳条件是：pH值分别是5.0、6.0；铀的初始浓度均为5.0mg/L；吸附时间均为1.0h；反应温度均为常温条件下(25℃)。动力学研究发现准二级模型都可对纳米Fe304粒子和Fe3O4-NH2纳米颗粒吸附铀的过程进行有效表达；热力学研究结果表明,纳米Fe304粒子和Fe3O4-NH2纳米颗粒吸附铀的过程都是自发的、吸热过程,且Fe3O4-NH2纳米颗粒比纳米Fe304粒子对铀的吸附能力有所提高；吸附解吸实验,结果表明纳米Fe304粒子和Fe3O4-NH2纳米颗粒的再生性能较好,进行6次吸附解吸实验后对铀的吸附率均仍可达80%以上。(3)通过包含大量氨基、羧基和羟基等功能团的磁性纳米Fe304粒子,与氯乙酰修饰后的啤酒酵母菌表面的羧基、羟基发生O-酰化反应和氨基发生N-酰化反应,实现了纳米Fe304粒子与啤酒酵母菌“接枝负载”,得到一种新型功能化吸附剂—纳米Fe304负载啤酒酵母菌(Nano-Fe3O4loading saccharomyces cerevisiae,NFSC),并对吸附剂NFSC吸附铀的行为和机理进行研究。实验结果表明：NFSC在溶液pH值7.0、铀初始浓度5.0mg/L、吸附剂投入量20mg以及NFSC粒径大小12nnm条件下,对铀的吸附性能最好。动力学研究发现准二级反应模型比准一级模型更能有效拟合NFSC吸附铀的过程。通过研究等温线模型发现NFSC吸附铀过程均能使用Langmuir和Freundlich模型进行描述。吸附剂NFSC进行8次吸附解吸实验后,对铀的吸附率均仍可达90%以上(4)以FeCl3·6H2O为铁源,二乙基磷酰乙基三乙氧基硅烷(PTS)和氨丙基三乙氧基硅烷(APS)为有机改性基团,提出了对介孔氧化硅SBA-15进行功能化改性新方法,得到了一种新型功能化磁性介孔氧化硅G-PA-SBA-15。研究了溶液pH值、反应时间、铀初始浓度和温度等因素对吸附铀的影响。结果显示：G-PA-SBA-15吸附铀达到最大吸附量时的pH值均为6.0；反应时间为1.0h；铀的初始浓度为20mg/L；吸附反应温度为25℃。动力学研究发现吸附剂G-PA-SBA-15吸附铀过程可以采用准二级反应动力学模型进行描述。等温线模型研究结果表明G-PA-SBA-15吸附铀的行为符合Langmuir吸附等温模型。吸附剂G-PA-SBA-15分别使用0.1mol/L的HCl、NaOH和EDTA等3种解析剂解析再生8次后,对铀的吸附率均在80%以上,说明吸附剂G-PA-SBA-15可以多次重复利用。更多还原

【Abstract】 Abstract:Uranium is not only the main components of the nuclear power, but also the necessary strategic material of the national defense construction. In order to meet the nuclear power development and the national defense construction demand (the nuclear war industry), it is still necessary to intensify of the intergrowth of Uranium mining and mineral smelting. However, lots of wastewater containing Uranium produced in the process of the Uranium mining and mineral smelting, will change the Uranium mines surrounding environment background radiation and the species genetic distortion. It would be a potential threat to human survival and social development, and also cause people’s health and the national economic development. Therefore, seeking a variety of novel functional adsorbents with high adsorption efficiency, good regeneration performance and low cost, is becoming more and more important.First, we have summarizesd the main pollution characteristics of the wastewater containing Uranium during the Uranium mining and metallurgy, harm and its processing method. At the same time, we have constructed a series of novel functional adsorbent materials with friend environment, good adsorption and regeneration performance, based on the complexing space structure of Uranyl ion. With the help of Fourier Transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray powder diffraction (XRD) and N2adsorption/stripping experiment, we have characterized all the various adsorbent. Using the simulation wastewater containing Uranium during Uranium mining and metallurgy as the research object, the method of static adsorption experiment was carried out a series of adsorption experiment, inspected the various influence factors on the properties of adsorbent, with a variety of adsorption dynamics/thermodynamic and isotherm models fitting of experimental data. The main research contents and results are as follows:(1) A new method was proposed-cystine chemical modification Saccharomyces Cerevisiae (SC) and a novel biological adsorbent was obtained——Modification Saccharomyces Cerevisiae (MSC).The adsorption characteristics of SC and MSC for Uranium were studied with the static adsorption experiment method, respectively. The results showed that the maximum Uranium adsorption quantities of SC and MSC were all in pH of6.0, and the maximum adsorption quantity of MSC q∞is6.5times this of SC. By the adsorption Uranium dynamics research of SC and MSC, we found the adsorption Uranium of SC and MSC had completed80%of the adsorption amount in1.0h, and the adsorption equilibrium have be achieved at about1.5h. And the secondary reaction kinetics model can better describe the adsorption process of SC and MSC for Uranium. Isotherm model research results show that the adsorption Uranium process of SC and MSC could all meet the Langmuir and Freundlich isotherm models.This showed that the control of Uranium adsorption rate may be a chemical adsorption process. Through the desorption experiment of SC and MSC, we found SC and MSC had a good regeneration performance, and the adsorption ability had not declined significantly after8times adsorption-desorption experiment.And it showed SC and MSC could be reused many times.(2) A new type of environmental protection and economy preparation method of Fe3O4nanoparticle was studied and we put forward a new method of surface functionalization modification of Fe3O4nanoparticle.The adsorption characteristics of Fe3O4nanoparticle and surface amine-functionalization of magnetic adsorbent Fe3O4-NH2for Uranium were studied with the static adsorption experiment method, respectively. The results showed that the best adsorption conditions of Fe3O4nanoparticle and Fe3O4-NH2nanoparticle is:pH value is5.0,6.0respectively; the initial concentration of Uranium are all5.0mg/L;the adsorption time are all1.0h; reaction temperature are all under the condition of normal temperature (25℃).By the adsorption Uranium dynamics research of Fe3O4nanoparticle and Fe3O4-NH2nanoparticle, we found that the secondary reaction kinetics model could better describe the adsorption process of Fe3O4nanoparticle and Fe3O4-NH2nanoparticle for Uranium. Thermodynamics research results show that the adsorption processes of Fe3O4nanoparticle and Fe3O4-NH2nanoparticle are spontaneous, endothermic. And the adsorption Uranium capacity of Fe3O4-NH2nanoparticle is bigger than this of Fe3O4nanoparticle.Through the desorption experiment of Fe3O4nanoparticle and Fe3O4-NH2nanoparticle, we found Fe3O4nanoparticle and Fe3O4-NH2nanoparticle had a good regeneration performance, and the adsorption Uranium rate could be still more than80%after6times adsorption-desorption experiment. (3) The "graft loading"was completed between the Fe3O4nanoparticle with a large number of amino, hydroxyl and carboxyl functional groups on the surface, and Saccharomyces Cerevisiae with carboxyl and hydroxyl groups on the surface, throughing the O-acylation reaction or N-acylation reaction. And a novel functional adsorbent was obtained—Nano-Fe3O4loading Saccharomyces Cerevisiae (NFSC). We have studied the adsorption Uranium performance and mechanism from the aspects of factors which influence the adsorption performance.The experimental results showed that the best adsorption Uranium conditions of the adsorben NFSC is: the pH value is7.0;the initial concentration of Uranium is5.0mg/L;the addition amount is20mg and the optimum size of NFSC is12nm. By the adsorption Uranium dynamics research of NFSC, we found that the secondary reaction kinetics model could better describe the adsorption Uranium, process of NFSC than the first order reaction kinetics model.Isotherm model research results show that the adsorption Uranium process of NFSC could all meet the Langmuir and Freundlich isotherm models. And the adsorption model is the combination of the monolayer coverage and the multilayer adsorption. Through the desorption experiment of NFSC, we found NFSC had a good repeated use performance, and the adsorption Uranium rate could be still more than90%after8times adsorption-desorption experiment.(4)A new functionalization modification method of the mesoporous silica SBA-15was proposed, with FeCl3.6H2O as source of iron, and diethyl phosphoryl ethyl triethoxy silane (PTS)and ammonia propyl triethoxy silane (APS)as the organic modification group.And a new type of functional magnetic mesoporous silica G-PA-SBA-15was obtained. We have studied the solution pH value, the reaction time, the initial concentration of Uranium and the influence of temperature on the adsorption of Uranium. The results showed that the G-PA-SBA-15would be the maximum adsorption quantity:pH value is6.0;the reaction time is1.0h; the initial concentration of Uranium is20mg/L;the adsorption temperature is25℃.By the adsorption Uranium dynamics research of G-PA-SBA-15,we found that the secondary reaction kinetics model could better describe the adsorption Uranium process of G-PA-SBA-15.Isotherm model research results show that the adsorption Uranium process of G-PA-SBA-15could meet the Langmuir model.The result shows that the adsorption sites on the surface of G-PA-SBA-15are evenly distributed, which have the same affinity of uranyl ion. And the adsorption model belongs to the monolayer adsorption model. Thermodynamics research results show that the adsorption processes of G-PA-SBA-15is spontaneous, endothermic. The temperature increase would improve the adsorption Uranium capacity of G-PA-SBA-15in a small range.Through the desorption experiment of G-PA-SBA-15,we found G-PA-SBA-15could be reused many times because the adsorption ability had not declined significantly, and the adsorption Uranium rate could be still more than80%after8times adsorption-desorption experiment Using0.1mol/L HC1, NaOH and EDTA.更多还原