Preparation of nanometer yellow iron and its UV absorption capacity

The nanometer yellow iron oxide was prepared by oxidizing Fe（OH）2 with air, which was verified with XRD and TEM. The result shows that nanometer yellow iron oxide is spindle-shaped and well-distributed with a long axis of 150-200 nm and short axis of 40-50 nm. Ultraviolet （UV） transmittance of the iron oxide shows the great effect of concentration on both transparency and UV ab- sorption, and it has been proven that iron oxide with a concentration of 0.025wt% is preferred. The spectrum of XRD indicates that it is goethite. When the yellow iron is dispersed in sol, given that the wavelength of UV is less than 300 nm, its UV absorption capacity is superior to those of ZnO and TiO2. The absorption capacity of the yellow iron is less than TiO2 and more than ZnO as the wavelength of UV is 300-400 nm.

Co-doping of Iron and Cerium in Titanium Dioxide: Observation of a Cooperative Effect

The co-doping of iron and cerium into TiO2 was studied by means of X-ray diffraction, Raman spectroscopy, UV Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, when separately doping via the sol-gel method, iron was introduced in the fralnework of anatase TiO2 whereas cerium was not; interestingly, both iron and cerium were introduced in tile framework when co-doping by the sol-gel method. The co-doped TiO2 behaves much more intense surface hydroxyl concentration than the separately-doped and pure TiO2. This observation demonstrates for the first time a cooperative effect in the co-doping of transitional metals in the framework of TiO2.

Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

The cerium iron complex oxides oxygen carrier was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carder could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carders were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carrier： the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species （bulk lattice oxygen） that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction condition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

Cerium Distribution in Spheroidal Graphite of Cast Iron

Six thin sections of spheroidal graphites in cast iron have been investigated by TEM and SEM.The spheroidal graphites consist of two or three layers and have nuclei which are composed of Ce_2O_2S and Ce_2O_3. Cerium is existed ont only in nuclei,but also in central layer and middle layer of graphite.

Synthesis, Crystal Structure and Magnetic Behaviour of Three Dimensional Iron-Cerium Cyanide Bridged Bimetallic Assembly

The complex with the formula [CeFe(CN)(6)(H2O)(3)]. 2H(2)O was synthesized and structurally characterized. It crystallizes in hexagonal, space group P3, a = 0.75320(10) nm, b = 0.75320(10) nm, c = 1.4374(3) nm, gamma = 120 degrees, V = 0.7062(2) nm(3), Z = 3, Be = 3.048 Mg .m(-3), F(000) = 606, mu = 6.346 mm(-1), T = 293(2) K, R-1 = 0.0169, wR(2) = 0.0459. The structure is a three-dimensional network containing open channels formed by the nine-coordinated CeN6(H2O)(3) groups and octahedral FeC6 groups through the cyanide linkages. Magnetic susceptibility measurements in the temperature range of 5.1 similar to 300 It show an antiferromagnetic interaction between the Ce3+ and Fe3+ ions.

Valence Control of Ce Ions in Cerium-substituted Yttrium Iron Garnet

Cerium-substituted yttrium iron garnet(Ce x Y 3-xFe 5O 12, Ce∶YIG) was prepared via coprecipitation. The structu re, morphology, valence state and constituent of Ce ions were investigated respe ctively. X-ray powder diffraction(XRD) analysis shows that Ce∶YIG was of singl e cubic YIG phase. The result of X-ray photoelectron spectroscopy(XPS) indicate s the Ce ions in Ce∶YIG were in the state of trivalence. Scanning electron micr oscope(SEM) demonstrates the conglobation of Ce∶YIG particles about 0.2μm scal e.The magnetic properties were studied by a vibrating sample magnetometer(VSM) a nd the result exhibits that substitution of Ce 3+ changes the magnetic para meters of YIG. The effects of doping content of Ce ions and synthesis temperatu re on valence control were discussed in detail.

The Effects of Ce on Hot Corrosion of Iron-based Alloys

Electrochemical polarization resistance technique was employed to study the effects of Ce on hot corrosion resistance of stainless steel 316, and preoxidation of surface-applied CeO2 coating on that of HK40 alloy. It is shown that a little Ce additives may improve hot corrosion resistance of stainless steel 316, especially inhibit the internal sulfidation along grain boundaries. The surface-applied CeO2 coating may greatly improve hot corrosion resistance of HK40 by promoting the formation of Cr2O3 scale.

阳离子树脂基铁锰铈吸附剂的制备及其去除水中铅、铬的性能研究

为了获得去除重金属离子Pb^(2+)和Cr^(6+)的特异性强、易回收的高性能吸附剂,通过将铁锰铈金属氧化物(Fe-Mn-Ce)负载到强酸性阳离子树脂(D001)上,成功制备了树脂基铁锰铈吸附剂(Fe-Mn-Ce@D001)。研究了吸附剂对水中Pb^(2+)、Cr^(6+)的去除性能,考察了不同因素对Pb^(2+)、Cr^(6+)去除率的影响,同时进行吸附动力学以及吸附热力学实验,探讨其吸附规律。实验结果表明:在温度为298K、pH=5、投加量为0.01g时,Fe-Mn-Ce@D001对Pb^(2+)和Cr^(6+)的饱和吸附容量分别为528.06mg/g和218.33mg/g,优于原树脂D001。Fe-Mn-Ce@D001树脂比D001对Pb^(2+)和Cr^(6+)具有更高的吸附选择性,在高浓度Ca^(2+)、Mg^(2+)、NO_(3)^(-)、SO_(4)^(2-)等离子共存的条件下仍保持较高的去除率;在Pb^(2+)和Cr^(6+)混合溶液中比D001具有更好的同步吸附性能;相对于D001具备更好地重复利用性。Fe-Mn-Ce@D001对Pb^(2+)和Cr^(6+)的吸附等温模型均符合Langmuir模型,吸附动力学行为与准一级动力学和准二级动力学均能很好的相符。

新型铈铁硼中铅含量的测定方法研究

通过对新型铈铁硼材料中铅含量的测定方法研究,开发了以电感耦合等离子体发射光谱(ICP⁃OES)法测定铈铁硼中铅含量的方法。实验研究了分析谱线的选择,以铈和铁为基体配制标准溶液,用6%体积浓度的稀硝酸低温加热消解铈铁硼,用基体匹配法测定了铈铁硼中铅的含量。最后通过方法检出限的计算、加标回收率实验、平行实验和重复性测试,验证了方法的可靠性。实验结果表明,该方法的检出限为0.007 mg/L,加标回收率为100.6%,样品中铅含量为0.006%,两次实验平行性好,重复性低于2.3%,数据准确可靠。该方法具备实验室可操作性,可以为新型铈铁硼生产中的铅含量杂质分析提供依据,也可为重金属污染检测提供参考。

地质聚合物复合材料固化稳定化铬污染土

六价铬是一种公认的人类致癌物质,且它能极易的渗透到土壤深处和含水层造成土壤的持久性污染。本文以氧化石墨烯为载体,采用液相还原法制备氧化石墨烯负载纳米铁。利用制备好的氧化石墨烯负载纳米铁对铬污染土进行预吸附处理。随后将预吸附铬土与高炉矿渣,粉煤灰,碱激发剂制备成复合地质聚合物。采用硫酸硝酸法测得复合材料铬浸出浓度为0.93 mg/L,低于纯地质聚合物的铬浸出浓度;复合地质聚合物抗压强度均大于40 MPa,可作为一般安全填埋物和建筑材料。对复合地质聚合物进行扫描电镜-能谱(SEM-EDS)表征测试,经纳米粒子处理后,钙矾石的形成增强了复合地质聚合物的力学性能。SEM-EDS结果表明复合地质聚合物主要通过还原反应、物理吸附和物理固封作用实现对铬污染土固化稳定化。

掺铁TiO_2纳米微粒的制备及光催化性能

采用溶胶 凝胶法制备了粒径为 60～ 70nm的掺铁TiO2 纳米微粒。用TG DTA、XRD、LDPSA、SEM等手段对其进行了表征。用UV Vis分光光度计研究了掺铁TiO2 纳米微粒的光吸收特性与光催化活性。结果表明 ,掺杂铁离子使TiO2 纳米粒径的粒径变小 ,光谱响应范围扩大。通过对苯酚的光催化降解研究 ,发现掺入质量分数为 0 0 5 %Fe的TiO2 与纯TiO2 相比其平均降解速率提高了 1 3

硫酸铈滴定法测定铁矿中铁

提出在HCl介质中,以抗坏血酸还原铁 ,残余的抗坏血酸以次甲基蓝为指示剂,硫酸铈氧化,然后在硫 磷混酸介质中,以二苯胺磺酸钠为指示剂,硫酸铈标准溶液滴定铁 。大多数常见离子不干扰铁的测定,氟的干扰可用硼酸消除。本方法简便、快速,用于铁矿中铁的测定,结果满意。

PP/纳米CeO_2复合纤维的制备及性能研究

将用偶联剂修饰后的纳米氧化铈(CeO2)、未修饰纳米CeO2以相同的比例与PP切片共混后熔融纺丝,并测定拉伸纤维的力学性能和染色性能。结果表明:加入用偶联剂修饰纳米CeO2的PP纤维的可纺性较好,力学性能比PP纤维下降少;而加入未修饰纳米CeO2后PP复合纤维的可纺性较差,力学性能有所下降。SEM照片表明,用偶联剂修饰后的纳米CeO2在纤维表面分布均匀,颗粒尺寸明显比未修饰纳米CeO2小。用分散染料在高温高压下对PP复合纤维进行染色,加入修饰后纳米CeO2纤维和未修饰纳米CeO2的PP纤维其吸收系数与散射系数的比值(K/S)比PP纤维分别增加了30.3%,45.5%,纤维的染色性能提高。

聚硅氮烷包敷纳米铁磁粉PSZFe的合成及其雷达波吸收性能研究

The preparation and micwave-absorbing behavior of nanosize PSZFe magnetic particles were studied.Nanosize PSZFe magnetic particles were prepared as following:nanosize Fe particles generated by themal decomposition of Fe(CO)-5 in organic solvents were encapsulated with synthesized polysilazane(PSZ) precursor and then irradiated under ultraviolet light.PSZFe particles were characterized by using transmission election microscope(TEM),X-Ray powder diffraction(XRD) and vibrating sample magntometer(VSM),and their microwave-adsorbing properties were measured by means of a vector network analyzer.The influence of the polysilazation layer on corrosion and magnetization of PSZFe particles and the relationship between polysilazation layer and micwave-absorbing behavior of PSZFe particles were investigated.Results showed that the average diameter of PSZFe particles was 30 nm,the structure of iron in PSZFe magnetic particles was α-Fe.The formation of a PSZ layer on nanosize Fe particles enchanced the corrosion resistance of PSZFe.In addition,PSZFe particles coated with 3 wt% PSZ demonstrated high corrosion resistance and fine microwave-absorbing ability as well.The reflection loss was less than -10 dB in the range of 9^8～16 GHz,and a reflection loss value of -20 dB was detected at 13 GHz.

化学共沉淀法制备的纳米Ni_(0.5)Zn_(0.5)Ce_xFe_(2-x)O_4铁氧体微波吸收特性研究

采用化学共沉淀法制备了纳米Ni0.5Zn0.5CexFe2-xO4（x=0,0.005,0.01,0.015）铁氧体吸波材料,用AV3618型微波矢量网络分析仪测试了样品在8.2-12.5GHz范围内的微波吸收特性,实验结果表明：稀土元素铈的含量影响材料的吸波性能,当x=0.01时,纳米Ni0.5Zn0.5CexFe2-xO4铁氧体的吸波性能最佳。对于Ni0.5Zn0.5Ce0.01Fe1.99O4铁氧体吸波材料,当涂层厚度为1mm时,在测试频段内有三个吸收峰,在8.8GHz处,其最大吸收衰减量为15.4dB,10 dB以上带宽达3.8GHz,适量掺杂稀土元素铈是提高镍锌铁氧体吸波材料性能的一种有效途径。

光亮微晶态镍铁合金箔电沉积

在氯化物-硫酸盐体系中, 采用电沉积的方法制得了光亮Ni-Fe二元合金箔. 研究了Ni2+与Fe2+的摩尔比(n(Ni2+)/n(Fe2+))及Cl-、硼酸、柠檬酸、糖精和十二烷基硫酸钠对电沉积Ni-Fe合金箔的铁含量和电流效率的影响规律. 当电流密度为10～13 A/dm2, pH值为3.17, 温度为50～55 ℃, 时间为10 min时, 得到了Fe含量(质量分数)为23.2%～63.0%, Ni含量为37.0%～76.8%, 厚度为30 μm左右的纳米微晶态Ni-Fe合金箔镀层. X射线衍射结果表明: 合金箔为NiFe固溶体织构, 晶粒细化, 属于纳米微晶体;合金箔表面光亮平滑;显微硬度(HR30T)为17.2～19.5, 抗拉强度为779.66 Mpa, 延伸率为1%, 电阻率为29.56～62.99 μΩ·cm, 其具有较强的韧性和耐腐蚀性能.

碳铵沉淀法制备纳米氧化铈的研究

采用碳铵沉淀工艺进行了纳米氧化铈制备的研究,探讨了表面活性剂的加入量对氧化铈颗粒大小的影响,随着表面活性剂量的增加氧化铈颗粒粒径减小;煅烧温度对氧化铈粉末性能影响较大,随着煅烧温度的升高氧化铈粉末的晶粒尺寸增大,比表面积减小,煅烧温度为450℃时就已经形成了立方相的氧化铈。优化工艺条件制备出了单一粒径小于50nm、团聚体粒度重量累积中值粒径D50<150nm,粉末比表面积大于15m2/g,粉末的团聚常数(D50/DBET)小于6,形状为球形的纳米氧化铈粉末。

纳米氧化铈催化作用研究探讨

总结了氧化铈在催化中的作用,指出了纳米粒子的表面效应及氧化铈自身特性对其催化性能的影响,分别从CeO2 作为催化剂、助剂、载体等方面对CeO2 在催化中的应用加以综述,介绍了制备纳米CeO2 超细粉体的常见方法,并结合有关研究结果提出了今后的研究方向。

水/油微乳液技术制备单分散纳米CeO_2

在十六烷基三甲基溴化铵+正丁醇/环己烷/水溶液组成的水/油型微乳液体系中,运用微乳液制备纳米粒子的原理,利用改进的两相液液法,测定了水/油微乳液的区域,并制备了纳米CeO2粉体。对制备得到的CeO2粉末的形貌特征、物相结构、成分等用透射电子显微镜、X射线衍射分析、热重差示扫描量热法和红外光谱测试进行了表征。结果表明在测定的微乳液区内能制备出颗粒分散性好,粒度分布均匀的纳米CeO2粒子,所得颗粒尺寸为3nm左右。