【作者】 石华强；

【导师】 傅洵；

【作者基本信息】 青岛科技大学 ， 应用化学， 2009， 博士

【摘要】 由于其特殊的光学、电学、光化学、电化学、力学及催化性能,纳米材料的制备及应用已经受到人们的广泛关注。探索简便、能耗低且环境友好的材料设计与合成的新途径、新方法,始终是纳米材料研究领域中的一个重要课题,实现纳米材料尺寸、分布和形貌控制,对纳米材料的表面改性和拓展纳米材料的应用领域仍然是化学、物理和材料学家关心的重要内容。溶剂萃取作为一种重要的、节能的分离技术,已广泛应用于湿法冶金、原子能工业、稀土元素分离等生产过程中。本论文除了利用常规的沉淀法、水热法和溶剂热法外,特别关注了从溶剂萃取体系或含有萃取剂的体系中制备合成不同性能、不同形貌的无机纳米材料和有机纳米流体。该研究不仅有助于丰富和发展溶剂萃取化学的理论、拓宽溶剂萃取化学在材料制备领域中应用,同时也为纳米材料的制备、组装、裁剪提供了一种新的思路,可实现材料的“分离-制备-应用”一体化,在研究成果的产业化方面也具有极其重要的意义。本论文的主要工作是在课题组前期研究Cyanex系列硫代磷(膦)酸和TOPO中性磷氧萃取剂界面性能和相行为的基础上,利用溶剂萃取技术和其它液相法制备无机纳米材料相结合,成功制备了多种不同形貌、不同表面特性的无机纳米材料、有机纳米流体和聚合物复合材料,探索了它们在摩擦学、传热学和电化学领域的应用,并讨论了材料的生长机理和应用机理。论文主要内容如下:(1)用Cyanex 301-加氢汽油/Na2MoO4-HCl萃取体系制备的负载有机相进行溶剂热反应(150℃),制备了表面修饰粒径约1-3μm的MoS2微球,研究了各种反应条件对产物大小、形貌的影响,讨论了微球形结构的形成机理。将表面修饰的MoS2微球分别分散到液体石蜡、500 SN和GL-4齿轮基础油中,分别用四球机和SRV微动摩擦磨损试验机对其进行了初步的摩擦学性能研究,并与商业级胶体MoS2进行了比较。结果表明,萃取剂Cyanex 301不但可以起到萃取作用、还原功能和提供硫源,而且本身对产物有很好的修饰作用。得到的MoS2微球很容易分散到液体石蜡等有机溶剂中,并且具有良好的分散稳定性能。由于制备的MoS2微球具有特殊的晶体结构、微观结构和表面吸附的有机基团,是一种很好的极压添加剂和润滑油添加剂。它们在摩擦过程中形成了由萃取剂长链烷基和活性元素S、P组成的化学吸附膜、摩擦化学产物组成的化学反应膜及化学沉积膜,从而有效地提高了润滑油的抗摩减磨性能。(2)由于MoS2特殊的晶体结构和较好的应用前景,本文探索了一种简单、低温、绿色的MoS2合成路线。以商业级Na2MoO4为钼源,CS2和乙二胺反应生成的H2S作为还原剂和硫源,通过原位水热合成法在150℃制备了由片状MoS2材料插成的粒径约400 nm的花形MoS2微球。实验比较了各种反应条件对生成MoS2样品结构和形貌的影响,如反应温度,反应时间,Mo和S元素的物量比,乙二胺用量,不同类型表面活性剂(PVP、CTAB、SDBS),外加硫源,外加还原剂和不同极性溶剂等,初步探讨了花形MoS2的形成机理。结果表明: 150℃下,当Mo和S元素的物质的量比为1:3时,即可制备出花形MoS2微球材料。整个反应过程可以分为还原和生长两个阶段,乙二胺的加入能大幅度提高H2S气体的产量,提供反应所需的硫源和还原剂,同时生成的前驱体-HN-CH2- CH2- NH- CS-和Mo有一定的配位作用,能够引导初始粒子的成形和生长。(3)用Cyanex 302-加氢汽油/Zn(CH3COO)2-H2O萃取体系采用沉淀法在加氢汽油溶剂中直接制备了白色、高负载量、含Cyanex 302表面修饰的ZnS粒子的有机纳米流体,实验详细分析了粒子的结构形貌特征、分散状态、表面特性以及在有机溶剂中的稳定性能和负载量,其中室温下汽油中的最大负载量可以达到24.4 g·L-1。由于Cyanex 302在整个反应中既作金属Zn2+的萃取剂,同时又作ZnS纳米粒子的表面修饰剂,所以得到的表面修饰的ZnS粒子很容易分散到液体石蜡和500 SN基础油等有机溶剂中并能稳定存在。实验还比较了不同基础油润滑体系中添加ZnS粒子前后极压性能和抗磨减摩性能的变化,初步探讨了其抗磨减摩机理,认为它们在液体石蜡和500 SN中的摩擦机理都可归因于边界润滑条件下的化学吸附膜、化学反应膜和化学沉积膜。在摩擦初期或载荷较小的情况下,主要是液体石蜡和500 SN基础油和修饰剂的减摩效果;随着时间的延长或者载荷的增大,ZnS粒子在摩擦副间起到了类似滚珠的作用,从而提高了基础油的抗磨减摩性能。(4)为了更加简单方便地制备较大量的非烷烃纳米流体并探索其导热性能,本文在PVP-Ag+-乙二醇体系中室温下采用直接还原得到了含PVP表面修饰、高负载量的纳米银-乙二醇流体。实验详细比较了各种反应条件对Ag纳米粒子结构、大小、形貌以及乙二醇纳米流体的稳定性、负载量的影响。结果显示由于PVP对银粒子有良好的表面修饰作用和纳米粒子自身的布朗运动,使得银粒子能稳定地分散于乙二醇流体中。其中当PVP含量为12.5 g·L-1时,Ag粒子最大负载量可以达到20.96 g·L-1。同时还用仿制的纳米流体导热系数测试装置测定了上述不同负载量流体的导热系数,结果表明纳米流体比纯乙二醇的导热系数明显提高,当银粒子的体积分数为0.06%时,纳米流体的导热系数提高了36%。通过与流体导热系数的理论模型比较,传统的Maxwell和Kumar模型不能够用于解释本文纳米流体导热系数的增大机理,还需要对纳米流体传热的机理进行更深入的研究。(5)在TOPO-汽油/盐酸-Zr(IV)萃取体系中采用中相沉淀法制备了介孔ZrO2纳米材料和SO42-/ZrO2固体超强酸,并以此为前驱体分别制备了聚苯胺、不同表面活性剂(PVP、CTAB、SDBS)修饰的ZrO2-聚苯胺、SO42-/ZrO2聚苯胺复合材料。实验研究了不同反应条件对复合材料结构、形貌、表面特性、导电率和电化学活性的影响。结果表明在PVP和苯胺盐酸盐共同作用下聚合生成了一种表面不光滑的球形“核-壳”结构的ZrO2-聚苯胺复合材料,该种材料具有良好的分散稳定性、较高的比表面积、较高的电导率和较为活泼的电化学性能。由于介孔ZrO2材料特殊的形貌结构,在一定的酸性条件下苯胺单体会有规律地吸附到这些粒子的表面,并沿一定的方向生长聚合,这样得到的聚苯胺复合材料具有较高的导电率和电化学活性。将得到的ZrO2-聚苯胺复合材料应用到DNA电化学传感器中,用3σ法计算PAT基因的检测限可达4.25×10-14 mol·L-1,为这种材料在电化学领域的应用提供了很好的条件。(6)本文还在不同萃取体系中用多种方法制备了多种金属硫化物、硒化物和氧化物,并对纳米材料的形成进行了机理分析。①用Cyanex 301-Zn2+萃取体系采用溶剂热法制备了ZnS无机纳米材料。②用Cyanex 302-金属离子萃取体系采用静界面反应法制备了CdS、CuS、MoS2和MoSe2纳米材料。首先利用萃取技术将一种金属离子反应物萃入到有机相中,另一种无机离子沉淀剂分散于水相,在室温静态条件下,通过界面反应制备了目标产物,化学反应发生在互不相容的水相和有机相的相界面上,有利于纳米材料的自由生长。③用Cyanex 301-Fe3+萃取体系采用萃取沉淀法制备了Fe(OH)3前驱体,再将前驱体进行煅烧、回流、溶剂热等热处理得到了不同形貌的Fe2O3纳米粒子。制备的Fe2O3纳米粒子可分散到有机溶剂中,形成稳定的铁磁流体。④将Cyanex 301直接作为表面活性剂采用微乳液法在醇-水混合溶剂中70℃制备了表面修饰、粒径约70 nm的片状MoSe2纳米材料,Cyanex 301的用量对于MoSe2的形成及形貌至关重要。我们认为,与典型表面活性剂相比,萃取剂不仅具有良好的表面活性,而且其优势在于它与金属的化学结合力较强,负载量较大,对扩大实验与拓展纳米材料的应用更加有利。更多还原

【Abstract】 Due to the excellent optical, electrical, photochemical, electrochemical, mechanical and catalytic properties of nanomaterials, much more attention has been paid to their preparation and applications. It is still a great challenge to develop a new, facile, and convenient, low-energy and environment-friendly method for preparing and designing nanomaterials. Although there were many reports, many chemists, physicists and materials scientists are devoting themselves to the controllable size, morphology and distribution, surface-modification and expansion of their applied research.As an important separation technology, the solvent extraction and separation were extensively applied in the field of hydrometallurgy, atomic energy industry and rare earth element purification. In this paper, the main attention has been paid to explore the preparation of inorganic nanomaterials and organic nanofluids from a solvent extraction system or a system containing an industrial extractant, then the application of the prepared materials or fluids in the field of tribology, heat transmit and electrochemical properties. In this study, the theory and experience of solvent extraction were both developed and enriched in the field of preparation materials, a new idea for the preparation of nanomaterials was also provided. Moreover, it has very important significance in industry to carrying out the“separation, preparation and modification”at the same time.The main purpose of this paper is, based on the interfacial properties of extractants and interfacial phenomenon appeared in the extraction systems, several kinds of inorganic nanomaterials and organic nanofluids are firstly synthesized from a solvent extraction system or a system containing an industrial extractant, then their related application and properties researches, such as the tribological properties, thermal conduction properties and preliminary electrochemical properties, are studied systematically, finally, the tribological, thermal conductivity and electrochemical mechanism are also discussed briefly. The main contents of this paper are as follows:(1) Mono-dispersed molybdenum disulfide micro-spheres with the diameter of 1~3μm have been successfully synthesized via extraction-solvothermal method at 150℃in the system of Cyanex 301(di- (2, 4, 4- trimethylpentyl) dithiophosphinic acid) -gasoline/Na2MoO4-HCl. The influences of reaction conditions were discussed while a mechanism was proposed to explain the formation of the micro-spherical structure. Moreover, the tribological properties (Extreme-pressure (EP) properties, anti-wear (AW) and friction-reducing properties) of liquid paraffin (LP), 500 SN and gear oil GL-4 containing the above surface-modified MoS2 micro-spheres (MS-MoS2) were also evaluated on a four-ball tester and an optimol SRV oscillating friction and wear tester and compared with those of commercial colloidal MoS2 (CC-MoS2). Results showed that the extractant Cyanex 301 acted as phase transferring agent, reductant, sulfur source and morphology-controlling agent in the whole procedure, and MS-MoS2 was a much better EP additive and AW and friction-reducing additive in the above base oils than CC-MoS2 because of the well modifying effect. The lubrication mechanism could be attributed to the chemical adsorption film, reaction film, deposition film and the existence of the rolling friction under the boundary lubricating conditions.(2) Due to the special crystal structure and good application potential of MoS2 materials, a facile, low-energy and green route to the preparation of molybdenum disulfide is explored in this dissertation. Flower-like molybdenum disulfide micro-spheres with the diameter of 400 nm were synthesized successfully by a simple in-suit hydrothermal method from the chemical reaction among the sulfur source of commercial reagents CS2, NH2(CH2)2NH2 and the molybdenum source of Na2MoO4?2H2O at 150℃for 24 h. The obtained MoS2 products were characterized by XPS, XRD, EDX, SEM and TEM technique, indicating that the flower-like spheres were built up of MoS2 thin flakes having a thickness of several nanometers. The influences of reaction conditions, such as the amount of ethylenediamine, reaction temperature, reaction time, the ratio of S to Mo, surfactant (PVP, CTAB and SDBS), etc, on the MoS2 formation process were studied to explain the evolution of flower-like spheres. The whole reaction could be divided into two parts, one is reductive stage and the other is growth stage. With the help of the formed (-HN-CH2-CH2-NH-CS-)n compound, the new formed MoS2 particles were induced to grow in all directions to form nano-sheets under the hydrothermal conditions. This facile synthesis method may provide an idea to produce other transition metal sulfides.(3) In this dissertation, stable organic nanofluids containing ZnS nano-particles modified by Cyanex 302 (di- (2, 4, 4-trimethylpentyl) monothiophosphinic acid) are prepared directly in gasoline via solvent extraction-precipitation method in the system of Cyanex 302-gasoline/Zn(CH3COO)2-H2O. The obtained organic fluids were so stable that ZnS nano-particles did not precipitate after keeping at room condition for more than six months when the loading concentration of ZnS was as high as 24.4 g?L-1. The influences of reaction conditions on the structure, morphology, dispersion properties and the loading concentration of nanoparticles in organic solvent were discussed briefly while a stabilization mechanism was proposed. Results indicated that because of well modifying effect, the obtained ZnS nano-particles could be well dispersed into organic solvents again and the new-formed nano-fluids were also very stable. Moreover, the tribological properties of base oil LP and 500 SN containing the above ZnS nano-particles were also studied with four ball machine and Optimol SRV oscillating friction and wear tester and compared with those of ZnS nano-particles obtained in ethanol-water mixed medium, showing that such a nanofluid containing modified ZnS particles has a lower friction coefficient and wear volume loss. The action mechanism could be deduced as the effective surface composite film composed of chemical adsorption film, chemical reaction film and deposition film under boundary lubrication conditions.(4) It is very important to prepare organic nanofluids at large scale simply for the application in the fields of the tribology and thermal conductivity. In this dissertation, ethylene glycol nanofluids containing high loading concentration of Ag nanoparticles modified with poly-(vinylpyrrolidone) (PVP) were obtained by a facile chemical reduction method at room temperature. The influences of reaction conditions on the size, morphology, dispersion and the loading concentration of Ag nanoparticles in organic solvent were discussed briefly while a stabilization mechanism was proposed. The results showed that the obtained Ag nanoparticles were well modified by PVP and the highest loading concentration of the corresponding nanofluid was about 21 g·L-1 when the additive amount of PVP is 1.25 g?L-1. Moreover, the thermal conductivity of the nanofluids containing the above Ag nanoparticles were also measured by the transient hot-wire method and compared with the traditional Maxwell and Kumar model, showing that such a nanofluid has a higher thermal conductivity coefficient, i.e., compared with pure ethylene glycol, the thermal conduction coefficient of 0.06% PVP-Ag ethylene glycol increased about 36%. It is expected that this method can be extended to synthesize other metallic nanofluids or nanoparticles.(5) On the basis of the studies about the phase behavior of TOPO (tri-alkyl phosphinic oxide)-gasoline/HCl-ZrOCl2 extraction system, crystals mesoporous ZrO2 and SO42-/ZrO2 with porous honeycomb-type structure are obtained using the third phase loading Zr(IV) by precipitation with ammonium solution under low temperature. Then the polyaniline, polyaniline-ZrO2 and polyaniline-SO42-/ZrO2 composite materials modified with different surfactants (PVP, CTAB and SDBS) are successfully synthesized, respectively. The influences of reaction conditions on the size, morphology, surface-modification, conductivity and electrochemical properties of polyaniline-ZrO2 composite materials were investigated respectively, while a stabilization and action mechanism were proposed to explain the change of chemical properties. Results indicated that the“core-shell”structure of polyaniline-ZrO2 composite materials were formed under the co-action of PVP and aniline hydrochloride, which has coarse surface, good dispersion, higher exterior area and sensitive conductivity and electrochemical properties. The aniline monomer would be well-regulated and adsorbed on the surface of ZrO2 and growth along the given direction, so the obtained composites are of higher conductivity and excellent electrochemical properties. The polyaniline-ZrO2 composites could be used for the detection the DNA hybridization. DNA specific-sequence related to PAT promoter gene with a detection limit ranging from 1.0×10-13 to 1.0×10-6 mol·L-1 and a detection limit of 4.25×10-14 mol·L-1 (3σ). It is expected that this polyaniline-ZrO2 composite materials can be applied in the electrochemical field in the future.(6) Because of the high surface activity of extractant, it could not only increase the loading concentration of metal ions in solvent, but also has very important significance in industry to carrying out the“separation, preparation and modifying”simultaneously through the solvent extraction system.①ZnS inorganic nanoparticles are successfully synthesized via extraction solvothermal method, which is very simple and could be used for preparation of other sulfides in a large scale.②CdS, CuS, MoS2 and MoSe2 semiconductors are successfully synthesized at the aqueous-organic interfaces via the chemical synthesis method. The Cd2+, Cu2+ and MoO22+ ions were extracted into organic phase by the Cyanex 301, then organic phase containing complexes were reacted with S2- (Se2-) in the aqueous phase at the aqueous-organic interfaces to synthesize sulfide nanomaterials, respectively, and the possible formation mechanism is proposed.③Surface modified Fe2O3 nanoparticles were successfully synthesized via different thermal treatment of the Fe(OH)3–Cyanex 301 precursor, which was obtained by the extraction-precipitation route. The obtained Fe(OH)3–Cyanex 301 precursor was given different thermal treatment, such as solvothermal reaction at 180℃, an intense refluxing boiling tetralin and calcine at 600℃respectively. Results indicated that Fe2O3 products were well-modified by Cyanex 301 and could be dispersed well into organic solvents to form the stable fluids due to the high affinity with non-polar solvent.④As surface modifying agent, flake-like MoSe2 nanomaterials were successfully synthesized via a chemical reaction in the mixed medium of ethanol and water at 70oC using home-made NaHSe as Se source, Na2MoO4·2H2O as Mo source and NH2OH·HCl as reducing agent. Results indicated that the morphologies of MoSe2 nanomaterials could be well controlled by the different concentration of extractant in this system and well-dispersed, flake-like MoSe2 nanomaterials with diameter of about 70 nm were obtained when the addition amount of extractant was 0.75 g·L-1.Compared with other typical methods in extractant systems, the studied approach have the advantages of strong cooperation and high loading concentration for metal ions. The theory and experience of solvent extraction were both developed and enriched in the field of preparation materials and their related applications.更多还原