【作者】 秦润华；

【导师】 李凤生；

【作者基本信息】 南京理工大学 ， 材料科学与工程， 2010， 博士

【摘要】 近来,纳米尖晶石型铁氧体作为一种重要的纳米磁性材料,由于其独特的磁学、电学和光学特性及其在磁靶向、磁吸附和磁分离领域的广泛应用而引起人们的极大关注。然而要在上述领域进行应用,首先要满足小粒径和高分散性的条件,其次还要满足表面具有用于负载药物、核素或金属离子的丰富功能基团的条件。因此,纳米尖晶石型铁氧体的控制制备及改性引起了全世界范围内科学家的研究兴趣。本论文在纳米尖晶石型铁氧体的制备、改性及其改性载体对金属离子的吸附方面,尤其在磁性载体对金属离子的吸附机理方面进行了研究。在第二章中,首先采用相对简单的低温固相反应法和化学共沉淀法分别制备了CoFe₂O₄、ZnFe₂O₄、Co_0.5Zn_0.5Fe₂O₄和Fe304几种典型的尖晶石型铁氧体纳米粒子,并对其进行了表征。结合测试结果,对几种铁氧体纳米粒子的磁性来源及其表现出的磁性特征进行了较深入地探讨和理论分析；对ZnFe₂O₄和Fe304纳米粒子表现出的异于块体材料的超顺磁性的原因进行了解释。在对几种铁氧体纳米粒子的饱和磁化强度进行对比的基础上,确定选用不易被氧化的CoFe₂O₄纳米粒子作为磁核,采用低温固相反应法进行制备。在第三章中,为了解决传统低温固相反应法制备CoFe₂O₄纳米粒子过程中普遍存在的团聚现象,提高产物分散性,提出了在前驱体混合物中分别添加惰性无机盐NaCl或分散剂PVA的新方法——盐助低温固相反应法和PVA助低温固相反应法。首先,分别研究了NaCl和PVA的用量以及煅烧温度对产物物相、分散性和形貌的影响,结果表明两反应体系在最佳条件下制得的CoFe₂O₄纳米粒子的D_XRD分别为16.1nm和16.7nm,比表面积分别为101.12m²/g和68.74m²/g,较传统低温固相反应法制得的CoFe₂O₄纳米粒子的比表面明显增大,团聚度明显减小；其次,探讨了盐助和PVA助低温固相反应法合成CoFe₂O₄纳米粒子的反应机理；最后,考察了NaCl和PVA对粒子分散性和形貌影响的可能机理。第四章以盐助低温固相反应法制备的高分散CoFe₂O₄纳米粒子作为磁核,以壳聚糖作为改性基体材料,分别制备了磁性壳聚糖、磁性N-位壳聚糖和磁性O-位壳聚糖。首先,用戊二醛作为交联剂,采用传统乳化交联法制备了以交联壳聚糖作为包覆层的磁性壳聚糖；其次,采用1-（3-二甲氨基丙基）-3-乙基碳二亚胺盐酸盐（EDAC）作为零-长程交联剂,对壳聚糖的C-2位一NH₂基进行酰胺化,分别制备了以EDTA-壳聚糖和DTPA-壳聚糖作为复合包覆层的磁性N-位壳聚糖；最后,采用一氯乙酸对壳聚糖的C-6位-OH基进行羧甲基化,再对羧甲基化壳聚糖进行酸酐化,然后采用醇解反应将酸酐化的羧甲基壳聚糖和CoFe₂O₄纳米粒子连接在一起,制备磁性O-位壳聚糖。至此,以壳聚糖作为基体材料的三种磁性载体被制备。第五章,分别以重金属离子Cu²⁺和Ni²⁺作为吸附对象,首先对第四章制得的三种壳聚糖基磁性载体的吸附性能进行了对比研究,结果表明以壳聚糖-螯合剂（EDTA/DTPA）复合材料作为改性材料制得的磁性N-位壳聚糖的吸附效果最好,磁性O-位壳聚糖次之,磁性壳聚糖最差。其次针对目前磁性壳聚糖载体的研究多以制备为主,对其性能研究较少,涉及机理的研究更是少之又少的现状,对三种壳聚糖基磁性载体对金属离子的吸附机理进行了较为深入地研究,并结合IR和XPS分析结果,分别确定了各载体参与吸附螯合的功能基团,提出了几种吸附模型,结果表明磁性壳聚糖的吸附机理类似于N·N型螯合剂,磁性N-位壳聚糖和磁性O-位壳聚糖的吸附机理则类似于N·O型螯合剂。更多还原

【Abstract】 Recently, nanometer spinel-type ferrites, as important nanometer magnetic materials, have attracted huge attention due to their unique magnetism, electricity and optics properties along with wide applications in magnetic targeted, magnetic adsorption and magnetic separation fields. However, several properties are required for the application in the above outlined several fields:they must be small in diameter and good in dispersibility, and must have functional groups of loading drug, radionuclide or metal ions. Therefore, controlled synthesis and modification of nanometer spinel-type ferrites have drawn continuous and worldwide research attention. In this dissertation, valuable explorations have been carried out on the preparation and modification of nanometer spinel-type ferrites along with metal ions adsorption aspect of modified carriers, especially in metal ions adsorption mechanism of magnetic carriers.In chapter 2, spinel-type CoFe₂O₄, ZnFe₂O₄, Co_0.5Zn_0.5Fe₂0₄ and Fe₃O₄ nanoparticles were prepared by relatively facile low temperature solid state method and chemical co-precipitation method, respectively, and were characterized. Uniting test results, the magnetism origin and their magnetic characteristics were discussed and analyzed, and the reasons of presenting superparamagnetism for ZnFe₂O₄ and Fe₃O₄ nanoparticles different from block materials were interpreted. Through comparing with the saturated magnetization of above outlined spinel-type ferrites nanoparticles, CoFe₂O₄ nanoparticles were chosen as magnetic core and low temperature solid state method chosen as synthesis method.In chapter 3, to solve the problem of particle agglomeration widely existing in traditional low temperature solid state synthesis of CoFe₂O₄ nanoparticles and enhance dispersibility of resultants, new methods, salt-assisted low temperature solid state method and PVA-assisted low temperature solid state method through introducing of inner inorganic salt NaCl or dispersant PVA in precursor mixtures were come up. Firstly, the effects on the phase, dispersibility and morphology of the resultants for NaCl and PVA addition amount and calcined temperature were investigated, respectively. The results indicated that the D_XRD of the as-prepared CoFe₂O₄ nanoparticles at optimal condition was 16.1nm and 16.7nm, and the surface area was 101.12m2/g and 68.74m²/g, respectively, it can be seen that the surface area increased apparently and the degree of agglomeration decreased apparently compared with the as-prepared CoFe₂O₄ nanoparticles via traditional low temperature solid state method. Secondly, the reaction mechanism of salt-assisted and PVA-assisted low temperature solid state synthesis of CoFe₂O₄ nanoparticles was discussed. Finally, the possible influence mechanism on particles dispersibility and morphology of NaCl and PVA was studied.In chapter 4, magnetic chitosan, magnetic N-site chitosan and magnetic O-site chitosan were prepared using the high dispersive CoFe₂O₄ nanoparticles prepared by salt-assisted low temperature solid state method as magnetic core and using chitosan as modifying based materials. First of all, using glutaraldehyde as crosslinking agent, magnetic chitosan which using crosslinking chitosan as coating layer was prepared via traditional emulsion crosslinking method. Next, using 1-Ethyl-3-（3-dimethyllaminopropyl） carbodiimide hydrochloride （EDAC） as zero-length crosslinking agent, through acylating C-2 site-NH₂ of chitosan, magnetic N-site chitosan which using EDTA-chitosan and DTPA-chitosan as hybrid coating layer, respectively, was prepared. Lastly, magnetic O-site chitosan was prepared through carboxymethylating C-6 site—OH of chitosan, anhydriding of carboxymethyl chitosan and alcoholysis reacting of anhydrided-chitosan, in turn. Thus, three kind of magnetic carriers using chitosan as based materials were prepared.In chapter 5, firstly, the contrastive research of adsorption properties of three kind of magnetic chitosan carriers prepared in chapter 4 was carried out using heavy metal ions Cu²⁺and Ni²⁺ as adsorption object, respectively. The results indicated that the adsorption properties of magnetic N-site chitosan using chitosan-chelating agent （EDTA/DTPA） hybrid materials as modifying materials were best, magnetic O-site chitosan were next and magnetic chitosan were last. Secondly, aiming at the actuality that the research of magnetic chitosan carriers mostly concentrated on preparation, less research on adsorption properties, and much less research on adsorption mechanism, the adsorption mechanism of three kind of magnetic chitosan carriers for heavy metal ions was studied, uniting the analysis results of IR and XPS, the functional groups of participating in chelating were confirmed, the adsorption model was put forward, and the results indicated that the adsorption mechanism of magnetic chitosan was similar to NN-type chelating agent, and that magnetic N-site chitosan and magnetic O-site chitosan were similar to N·O-type chelating agent.更多还原