Hydrothermal Synthesis of Cerium(IV) Oxide

CeO₂ powders have been prepared from cerium(III) nitrate, cerium(IV) sulfate, and cerium(IV) ammonium sulfate under hydrothermal conditions at 120° to 200°C for 5 to 40 h. The effects of the starting cerium compounds, hydrothermal treatment temperature, and the concentration of the solutions on the crystal growth of CeO₂ were investigated. CeO₂ powders hydrothermally synthesized at 180°C for 5 h from cerium(IV) salts had very fine particle sizes (30 Å); on the other hand, the powder from the cerium(III) salt had a relatively coarse particle size (160 Å). Although the crystallite size of the powder synthesized from the cerium(IV) compounds depended on the treatment temperature, that from the cerium(III) compound was insensitive to the treatment temperature. The mechanisms for the growth of CeO₂ particles under hydrothermal conditions are discussed.     

肉豆蔻酸稀土复合热稳定剂对PVC性能的影响

合成了肉豆蔻酸镧、肉豆蔻酸铈、肉豆蔻酸钕三种稀土热稳定剂,采用刚果红法分别测试了其与硬脂酸锌、季戊四醇、硬脂酸钙之间的协同作用,复配得到了硬质PVC用新型肉豆蔻酸稀土复合热稳定剂。利用转矩流变仪、动态力学谱仪等考察其对PVC流变性能和力学性能的影响。研究结果表明：肉豆蔻酸稀土复合热稳定剂具有良好的热稳定性,静态和动态热稳定时间约为120min和60min,能较好地抑制PVC的初期着色性;复合稀土体系的加工流变性能优于铅盐体系;拉伸强度、断裂伸长率和断裂强度与铅盐体系相当,而冲击强度高于铅盐体系。     

二氧化铈掺杂中空碳纳米纤维的制备及电化学性能

以葡萄糖为碳源,硝酸铈为铈源,去离子水做溶剂合成前体,使用实验室自制阳极氧化铝模板（anodized aluminum oxide,AAO）作为硬模板,采用真空压力诱导技术将前体注入到AAO的纳米孔道内,热分解合成二氧化铈纳米粒子（CeO₂-NPs）掺杂的中空碳纳米纤维（CeO₂/HCFs）。使用拉曼光谱、电感耦合等离子体质谱（ICP-MS）、透射电镜（TEM）、X射线衍射仪（XRD）、X射线光电子能谱（XPS）对样品进行表征,结果表明,CeO₂/HCFs具有平均直径约为200nm的中空管状结构,具有较好的碳化程度,CeO₂-NPs均匀分布在HCFs中,其晶型为面心立方晶系。通过循环伏安法（CV）与安倍电流-时间法（I-t曲线）技术,研究了支持电解质的pH对检测结果的影响以及CeO₂/HCFs对抗坏血酸的电化学催化性能,实验结果表明支持电解质在pH=4.18时具有最稳定的检测电流,CeO₂/HCFs对抗坏血酸有较高的电化学活性,修饰电极的灵敏度为505.4μA/(cm²·mmol),检出限为0.55μmol/L,线性范围为2.5~8.4mmol/L,具有良好的选择性、稳定性和重现性。该方法快捷、灵敏、稳定、操作简便,具有较大的应用潜力。     

Plant-based synthesis of cerium oxide nanoparticles as a drug delivery system in improving the anticancer effects of free temozolomide in glioblastoma (U87) cells

Nowadays, nanocarriers were proven to contain the potential of improving cancer treatments and are utilized to carry anticancer medications to tumors. In this study, cerium oxide nanoparticles (CeO₂-NPs) were synthesized by using Caccinia macranthera leaf extract as the stabilizer and reducer agent, as well as cerium nitrate salt as the supplier source of cerium. The synthesized CeO₂-NPs were analyzed through different procedures such as UV–Vis, FTIR, FESEM/EDX/PSA, XRD, XPS, and TGA/DTA. The outcomes of XRD and FTIR analyses con?rmed the synthesis of pure and crystalline structures of CeO₂-NPs. The average size and zeta potential of our nanoparticles were about 30 nm and ?18.5 mV, respectively. According to the results of XPS analysis, the percentage of Ce⁴⁺ was more than that of the Ce³⁺ oxidation state in synthesized NPs. The CeO₂-NPs were loaded with Temozolomide (TMZ) as an anti-cancer drug through electrostatic interaction and the produced nano-drug (CeO₂-TMZ) was delivered to glioblastoma multiforme (GBM) tumor cells. In conformity to the observations, the drug loading content (DLC) and drug loading efficiency (DLE) of CeO₂-TMZ were about 89.10 and 20.29, respectively. In comparison to the TMZ drug, the in vitro assay exhibited the exertion of higher antiproliferative activities, cell cycle arrest, apoptosis, and expression of p53 by CeO₂-TMZ, which proves the promising capability of this drug as a remedial factor for cancer treatment.     

Effect of the Ce3+ concentration on laser-sintered YAG ceramics for white LEDs applications

This paper describes the laser sintering and luminescence properties of Y₃Al₅O₁₂ (YAG) phosphors doped with different concentrations of Ce³⁺ and synthesized using the polymeric precursor method. The ceramics were sintered by a new laser sintering technique in which a CO₂ laser is employed as the heating source. The resultant ceramics exhibited a homogeneous microstructure with narrow grain size distribution and high relative density. The introduction of Ce³⁺ ions led to luminescence quenching at a concentration above 0.5 mol% and a redshift of the emission spectrum band with increasing cerium concentration. The excitation spectrum showed two characteristic bands centered at 340 nm and 460 nm and a relative change in their intensity by change the Ce³⁺ concentration. The presence of a single valence (Ce³⁺) of cerium was determined by X-ray absorption near edge structure measurements.     

马来海松酸铈的制备及应用研究

以马来海松酸和醋酸铈为原料,合成马来海松酸铈,探讨工艺参数对产物的影响。通过傅里叶红外光谱仪、扫描电子显微镜、X射线衍射仪对产物进行分析和表征。通过刚果红试纸法和热烘箱法研究了马来海松酸铈对聚氯乙烯（PVC）热稳定作用。结果表明,马来海松酸和醋酸铈反应的最佳摩尔比为1∶1.8,反应温度为60 ℃,时间为6 h,产率达95 %以上;马来海松酸铈对PVC有较好的热稳定性效果。 关键词: 聚氯乙烯;马来海松酸铈;热稳定性;制备     

燃烧法快速合成黄色可控轻质纳米氧化铈

以硝酸铈为氧化剂和抗坏血酸为燃烧剂,采用燃烧法快速合成纳米氧化铈,并用XRD、IR、UV、SEM等技术进行表征.同时进行燃烧剂、煅烧温度、盐助溶剂的考察.得出燃烧法的最佳实验条件为:n(硝酸铈)∶n(抗坏血酸)=1∶2,可以不加助溶剂,不经洗涤、煅烧.在此条件下所制备的氧化铈质量轻,颗粒细.     

稀土元素在铝合金阳极氧化后处理中的应用

研究了将稀土盐（如铈盐）用于铝合金阳极氧化后处理，测量了氧化膜在酸、碱介质中的耐蚀性。结果表明，经铈盐处理后，铝氧化膜的耐酸性明显提高，优于常温封闭处理，耐碱性却降低。这可能是由于氧化膜孔中的稀土化合物在碱性介质中优先溶解。     

不同方法合成铈掺杂介孔分子筛的结构性能

以硅酸钠、硝酸铈铵为原料,十六烷基三甲基溴化铵为模板剂,分别在微波辐射和水热条件下,合成稀土元素铈掺杂的介孔分子筛（CeMCM-41）。采用X射线粉末衍射（XRD）、透射电子显微镜（TEM）、紫外–可见分光光度计（UV–vis）和N2吸附-脱附等技术对合成的样品进行表征,研究了2种不同方法合成的CeMCM-41的介孔有序性和结构性能。结果表明：在2种不同的合成条件下,成功合成出铈掺杂的MCM-41介孔分子筛,其比表面积高于800 m2/g。合成条件影响着所合成的介孔材料的结构性能。     

Amphiphilic cerium(III) β-diketonate as a catalyst for reducing diesel/biodiesel soot emissions

This work reports on the synthesis, characterization and applications of the new cerium(III) β-diketonate Ce(hdacac)₃(Hhdacac)₃·2H₂O (where hdacac and Hhdacac denote, respectively, the hexadecylpentane-2,4-dionate and hexadecylpentane-2,4-dione ligands) as catalyst for the reduction of automotive emissions. Due to its amphiphilic character, this complex can be solubilized in non-polar fuels, thus generating cerium(IV) oxide particles, which efficiently catalyze the oxidation of diesel/biodiesel soot.The synthesized complex was characterized by microanalysis (C, H), thermal analysis, and infrared spectroscopy. Scanning electron microscopy, X-ray diffractometry, and specific surface area measurements attested that the complex can act as a soluble precursor of homogeneous CeO₂ spherical nanoparticles. The efficiency of this compound as catalyst for the reduction of soot emission was evaluated through static studies (comprising carbon black oxidation), which confirmed that increasing concentrations of the complex result in lower carbon black oxidation temperatures and lower activation Gibbs free energies. Dynamic studies, which embraced the combustion of diesel/biodiesel blends containing different amounts of the solubilized complex in a stationary motor, allowed a comparative evaluation of the soot emission through diffuse reflectance spectroscopy. These analyses provided very emphatic evidences of the efficiency of this new cerium complex for the control of soot emission in diesel/biodiesel motors.     

硅橡胶耐高温用含铈聚硅氧烷的制备及应用

本文以硅氧烷、氢氧化钾、无水氯化铈为原料,制备了一种与硅橡胶结构相似的含铈硅氧烷(PSC)。研究PSC用量、硅氧烷种类以及不同耐热添加剂对硅橡胶耐高温性能的影响。通过红外光谱对PSC结构进行表征,力学测试、热重分析、扫描电镜研究其加入硅橡胶前后的性能。结果表明：在250℃×24h和300℃×8h热老化条件下,随PSC用量增加,硅橡胶的拉伸强度、断裂伸长率和撕裂强度先增加后降低,硬度基本保持不变,PSC加入量为5%时,材料具有最佳的力学强度。PSC在硅橡胶中分散均匀,其加入起后始分解温度提高了250℃。     

Novel synthesis of cerium hexaboride by hexamine route

An endeavor has been made to prepare cerium hexaboride using a mixture of cerium nitrate, boron trioxide, and hexamine as a fuel burning at a relatively low temperature (500°C). The product was characterized by X-ray diffraction (XRD), FT-IR, TGA/DTA, SEM, and TEM. The upshot of the exploration exemplifies that CeB6 with a crystallite size of about 50 nm can be beneficially prepared. Some impurities are also perceived with the pure compound, which embodies the presence of lower valence cerium borides.      

寡聚酸合铈(Ⅲ)的合成及抗氧化作用的研究

在水-乙醇介质中,以寡聚酸钾与硝酸铈反应,合成寡聚酸合铈(Ⅲ)配合物,采用正交实验,考察了V水∶V乙醇、反应温度、反应时间对螯合反应的影响。结果表明,最优反应条件为:V水∶V乙醇=1∶3;温度50℃,时间6 h。通过红外光谱、紫外光谱和差热-热重分析测试手段对配合物进行了表征。红外光谱和紫外光谱均显示,Ce3+与寡聚酸配位,寡聚酸合铈(Ⅲ)配合物中金属配位方式为双齿配位。抗氧化作用研究表明,寡聚酸钾和寡聚酸合铈(Ⅲ)配合物均具有抗氧化活性,配合物与寡聚酸钾相比,对.OH有更高的清除活性。     

Characterization and synthesis of Ce-incorporated mesoporous molecular sieves under microwave irradiation condition

Ce-incorporated MCM-41 mesoporous molecular sieves (CeMCM-41) were synthesized by microwave irradiation method from sodium silicate and ammonium cerium (IV) nitrate precursors and using cetyltrimethyl ammonium bromide (CTAB) as template. The resulting samples were characterized by means of XRD, TEM, FT-IR, UV-Vis, XPS and N₂ physical adsorption, respectively. The effect of the Si/Ce molar ratio on the textural properties of CeMCM-41 was investigated. The results reveal that the CeMCM-41 was successfully synthesized. The resultant mesoporous materials have specific surface areas in the range of 602–1,216 m²/g and pore sizes in the range of ca. 2.6–2.9 nm. The structural properties are related to the amount of cerium incorporation. The surface area and pore volume of the resulting CeMCM-41 were gradually reduced as the cerium content in the sample increased, and the mesoporous ordering diminished.     

Preparation and Spherical Agglomeration of Crystalline Cerium(IV) Oxide Nanoparticles by Thermal Hydrolysis

Crystalline cerium(IV) oxide nanoparticles with a cubic fluorite structure could be synthesized from cerium(IV) ammonium nitrate solutions with a relatively high concentration of cerium(IV) (such as 0.5 mol/dm³) via thermal hydrolysis at 150°–240°C. The effects of the treatment temperature, the salt concentration, and the addition of sulfate ions on the crystallite size and morphology of the synthesized particles were investigated. The crystalline nanoparticles had a tendency to agglomerate and form spherical secondary particles with the addition of either ammonium sulfate or sulfuric acid. The existence of sulfate ions in the acidified solution was confirmed to be a factor of consequence for spherical agglomeration of the nanoparticles.     

硝酸铈铵复盐制备工艺研究

对硝酸铈铵复盐的制备工艺进行了研究。分析了反应物的加入量、反应温度、反应时间以及其它工艺条件对制备硝酸铈铵复盐产品质量的影响。得出了制备分析纯硝酸铈铵复盐的方法。该方法可获得纯度达99%以上的橘红色硝酸铈铵复盐,收率达85%以上。     

Nanostructured sol-gel coatings doped with cerium nitrate as pre-treatments for AA2024-T3: Corrosion protection performance

Nanostructured hybrid sol-gel coatings doped with cerium ions were investigated in the present work as pre-treatments for the AA2024-T3 alloy. The sol-gel films have been synthesized from tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) precursors. Additionally the hybrid sol was doped with zirconia nanoparticles prepared from hydrolyzed tetra-n-propoxyzirconium (TPOZ). Cerium nitrate, as corrosion inhibitor, was added into the hybrid matrix or into the oxide nanoparticles.The chemical composition and the structure of the hybrid sol-gel films were studied by XPS (X-ray photoelectron spectroscopy) and AFM (atomic force microscopy), respectively. The evolution of the corrosion protection properties of the sol-gel films was studied by EIS (electrochemical impedance spectroscopy), which can provide quantitative information on the role of the different pre-treatments. Different equivalent circuits, for different stages of the corrosion processes, were used in order to model the coating degradation. The models were supported by SEM (scanning electron microscopy) measurements.The results show that the sol-gel films containing zirconia nanoparticles present improved barrier properties. Doping the hybrid nanostructured sol-gel coatings with cerium nitrate leads to additional improvement of the corrosion protection. The zirconia particles present in the sol-gel matrix seem to act as nanoreservoirs providing a prolonged release of cerium ions. The nanostructured sol-gel films doped with cerium nitrate can be proposed as a potential candidate for substitution of the chromate pre-treatments for AA2024-T3.     

硅钨酸稀土盐催化合成丁基多苷

以硅钨酸铈为催化剂。以葡萄糖和正丁醇为原料,采用直接法合成了丁基多苷。详细地研究了醇糖摩尔比、反应温度、催化剂用量和反应时间等因素对葡萄糖转化率的影响,得出最佳反应条件。结果表明：当反应中醇糖比为5：1,油浴温度120℃,反应时间2h,催化剂的量为葡萄糖质量的3％,反应的转化率最高,可达到96．81％。比较了不同硅钨酸稀土盐的催化活性。同时以二氧化硅负载硅钨酸镧和硅钨酸铈作为催化剂．考察活性组分的负载量对葡萄糖转化率的影响。并考察了债载催化剂的萤复利用性能。     

硫酸高铈改性离子交换树脂催化合成丁酸异丁酯的研究

采用硫酸高铈与阳离子交换树脂反应制备的改性离子交换树脂催化合成丁酸异丁酯。考察了催化剂用量、醇酸物质的量比、反应时间、带水剂种类及催化剂重复使用性等因素对收率的影响。结果表明该催化剂与反应体系形成非均相物系,具有易分离回收,催化活性高,反应时间短,出水速率快,合成工艺流程简单,操作方便,不易腐蚀设备,废液排放量少,不需加带水剂即可获得较为理想的收率等优势,基本革除了浓硫酸为酯化催化剂存在的设备腐蚀严重、后处理工艺复杂、废液排放量多等弊端。硫酸高铈改性离子交换树脂是合成丁酸异丁酯的高效、经济且环境友好的酯化催化剂,具有一定的工业化应用前景。适宜反应条件为:正丁酸0.15mol,醇酸物质的量比1.3,催化剂2.0g,反应时间40min,收率85.7%。     

硫酸高铈催化合成氯乙酸乙酯

考察了硫酸高铈催化合成氯乙酸乙酯。详细探讨了影响酯化反应的条件 ,确定了最佳工艺参数。研究表明 ,硫酸高铈具很高的催化活性。