Sulfidation/regeneration multicycle testing of nickel-modified ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> desulphurization sorbent

A commercial metal oxide sorbent for the desulphurization of coal-derived gas requires high desulphurization reactivity, mechanical strength, ability to regenerate, and stability to endure many sulfidation-regeneration cycles. In this paper, the sulfur capacity and multiple cycles of a nickel-modified ZnFe₂O₄ sorbent prepared by the sol-gel auto-combustion method were measured in a fixed-bed reactor at middle temperature of 300°C (sulfidation temperature) and 500°C (regeneration temperature). Also, the BET surface area, pore volume, average pore diameter and X-ray diffraction (XRD) patterns of the sorbent through multicycles were studied. Multicycle runs indicate that the sulfidation reactivity decreases slightly during the second cycle and keeps steady in the following cycles. The results indicate that the nickel-modified ZnFe₂O₄ keeps high reactivity and structural stability in the multicycle testing of sulfidation/regeneration.     

ZnFe2O4高温煤气脱硫剂的还原与硫化

采用共沉淀法制备了ZnFe2O4高温煤气脱硫剂,并在动态热天平上对其还原和硫化行为进行了研究,分别考察了温度、反应气氛对脱硫性能的影响。低于300℃,还原反应基本不发生：在450℃出现ZnFe2O4脱硫剂的最大还原速率：CO还原能力远不及ZnFe2O4脱硫剂硫化反应速率与浊度、H2S浓度成正比,300℃左右出现ZnFe2O4脱硫剂的最大硫化速率。还原与硫化反应可用等效应粒子模型描述,ZnFe2O4脱硫剂的还原与硫化反应存在控制段的转移。     

纳米铁酸锌(ZnFe2O4)的表面改性

采用化学修饰方法,以二氧化硅为内层修饰材料,r-氨丙基三甲氧硅烷(APS)偶联剂为外层修饰材料,对磁性ZnFe2O4纳米粒子进行了双层修饰。并采用XRD、IR、Zeta电位对未包裹粒子,二氧化硅包裹的磁纳米粒子,APS和二氧化硅双层包修饰的纳米磁粒进行表征。同时也比较了三种粒子的耐酸性能。结果显示硅包裹的纳米磁粒Zeta电位明显向酸性方向移动,而双层的纳米磁粒Zeta电位向碱性方向移动。包裹的纳米磁粒在pH2.0的酸中具有很好的耐酸性能,而未处理的纳米粒子在酸溶液中发生了溶解。     

复合催化剂ZnFe2O4/FeVO4的制备及光催化性能

为了降解污水中的有机染料,对复合催化剂ZnFe2 O4/FeVO4光降解有机染料进行了研究,以促进水中生物的健康生长和整个生态系统的平衡.通过聚乙烯吡咯烷酮(PVP)辅助水热法制备出了ZnFe2 O4,通过水热法制得了FeVO4,并按照ZnFe2 O4和FeVO4不同质量比合成了复合催化剂ZnFe2 O4/FeVO4....     

ZnFe2O4/ZnO气相法催化合成烷基吡嗪的研究

：改进的柠檬酸络合法制备了ZnFe2O4/ZnO催化剂,并用于乙二胺和2,3-丁二醇环化脱氢制备烷基吡嗪。用 X 射线衍射(XRD)、傅立叶红外光谱（FT-IR）对催化剂进行了表征。考察了Zn/Fe摩尔比、反应温度、载气空速对2,3-丁二醇转化率和烷基吡嗪选择性的影响。结果表明,在n(Zn):n(Fe)=2:1、反应温度380℃,原料液流速0.02mol/min,载气空速1440 h-1时,2,3-丁二醇的转化率为93.38%,烷基吡嗪的收率为85.47%,其中2,3-二甲基吡嗪的收率为22.16%、2-甲基吡嗪的收率为63.31%。     

Ultrasound assisted synthesis of heterostructured TiO2/ZnFe2O4 and TiO2/ZnFe1.98La0.02O4 systems as tunable photocatalysts for efficient organic pollutants removal

As a response to the everyday growing concern about wastewater treatment, some new mesoporous TiO₂/ZnFe₂O₄ and TiO₂/ZnFe_1.98La_0.02O₄ catalysts were synthesized during this research. The ultrasound template-assisted sol-gel method was employed in the synthesis, using conventional calcination and microwave treatment for pore directing agent removal. The as-prepared samples were characterized from the structural, optical, morphological and textural points of view, confirming the presence of spinel ferrites and TiO₂ anatase crystals in the nanocomposites. The synthetized powders exhibit promising characteristics for their use in adsorption and light activated degradation of organic pollutants. The photodegradation experiments of model pollutant basic blue 9 (methylene blue) dye were performed at laboratory scale and the optimum experimental parameters were determined as 0.4 g/L catalyst and 30 mg/L initial dye concentration, under UV light irradiation, visible irradiation and natural sun light irradiation. The conventionally calcined lanthanum doped TiO₂/ZnFe_1.98La_0.02O₄ system exhibited the highest efficiencies of 97%, 70% and 91% for dye removal from the solution, under UV light, visible light and natural sun light irradiation, respectively. Moreover, the catalytic activity was similar for up to four consecutive cycles. A lower yield of organic pollutant removal was observed in wastewater treatment plant (WWTP) effluent. The obtained results show that the newly synthesized catalysts are good candidates for the removal of water pollutants through adsorption and photocatalysis.     

ZnFe2O4粉体的燃烧合成

采用燃烧合成法制备了ZnFe2O4。研究了ZnFe2O4粉体燃烧合成温度、燃烧波速度与放热系数k、氧气压力p和填装密度等参数之间的相互关系，讨论了ZnFe2O4形成机制，并通过SEM，EDS，XRD和Mossbaur谱(MS)等分析测试手段对产物的形貌、物相、结构及性能进行了分析。结果表明：用大颗粒Fe粉(≤45μm)原料制备ZnFe2O4的合成反应属于固-液反应，主要由溶解-析出机制控制；产物中含有部分亚稳相Fel-xO；在l550-l600K之间ZnFe2O4晶格结构完整，转换率较高。     

ZnFe2O4高温煤气脱硫剂的再生

在热天平上对自制的ZnFe2O4脱硫剂进行了再生工艺研究，考察了再生温度、O2浓度对ZnFe2O4脱硫剂再生性能的影响；进行了多次硫化、再生循环实验，并与加入玻璃粉的样品进行了比较。结果表明，700℃下氧含量2.0%(vol)时再生可以获得良好的再生率和二次硫化反应活性；玻璃粉的少量加入，会改善脱硫剂长期使用的稳定性，但反应活性有所下降。     

玻璃基片上ZnFe2O4薄膜光催化降解性能的研究

采用旋转镀膜法在玻璃表面制备了ZnFe2O4薄膜，通过改变ZnFe2O4的浓度、烧成温度及薄膜层数，研究了ZnFe2O4薄膜的均匀性及对甲基橙的光催化降解性能。结果表明，ZnFe2O4薄膜均匀性好，对甲基橙有较高的分解效果。     

中空ZnFe2O4微球的合成及其电化学性能

以Zn(Ac)2×4H2O和FeCl3×6H2O为主要原料,采用一步水热法合成了中空结构的ZnFe2O4微球,对其物相、形貌和组成进行了分析. 结果表明,中空ZnFe2O4粒径微球约300 nm,壳厚约25 nm. 以其为锂离子电池负极材料,100 mA/g电流密度下,首次放电容量为1524 mA×h/g, 50次充放电循环后容量约为826 mA×h/g,呈现出优异的循环性能.     

Preparation,structural, and electrical studies of polyaniline/ZnFe2O4 nanocomposites

Polyaniline/ZnFe₂O₄ nanocomposites were synthesized by a simple and inexpensive one‐step in situ polymerization method in the presence of ZnFe₂O₄ nanoparticles. The structural, morphological, and electrical properties of the samples were characterized by wide angle X‐ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). WAXD and SEM revealed the formation of polyaniline/ZnFe₂O₄ nanocomposites. Infrared spectroscopy indicated that there was some interaction between the ZnFe₂O₄ nanoparticles and polyaniline. The dc electrical conductivity measurements were carried in the temperature range of 80 to 300 K. With increase in the doping concentration of ZnFe₂O₄, the conductivity of the nanocomposites found to be decreasing from 5.15 to 0.92 Scm⁻¹ and the temperature dependent resistivity follows ln ρ(T) ∼ T^−1/2 behavior. The nanocomposites (80 wt % of ZnFe₂O₄) show a more negative magnetoresistance compared with that of pure polyaniline (PANI). These results suggest that the interaction between the polymer matrix PANI and zinc nanoparticles take place in these nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrospinning synthesis of ZnFe2O4/Fe3O4/Ag nanoparticle-loaded mesoporous carbon fibers with magnetic and photocatalytic properties

The sol–gel method combined with electrospinning was used to synthesize polyvinylpyrrolidone nanofibers loaded with a mixture of Zn(Ac)₂·2H₂O, Fe(NO₃)₃·9H₂O and AgNO₃, which generated mesoporous carbon fibers loaded with compounds including ZnFe₂O₄, Fe₃O₄ and Ag after heat treatment at 850 °C in a N₂ atmosphere. Mesoporous carbon fibers loaded with ZnFe₂O₄–Fe₃O₄–Ag had a uniform pore size distribution, high specific surface area and strong ferromagnetism. They displayed high photocatalytic activity toward the degradation of methylene blue and methyl orange under visible light irradiation. This kind of complex magnetic semi-conductive mesoporous carbon fiber can be repeatedly used as a photocatalyst to dispose of organic wastewater. This simple synthesis method can be used to prepare other complex materials with multi-functional components.     

纳米锌铁氧体研究现状及发展前景

简要介绍了纳米锌铁氧体（ZnFe2O4）的研究现状。详细分析了目前国内外纳米锌铁氧体的主要制备方法及研究进展,比较了各种制备方法的优缺点。结合相关行业的发展,指出纳米锌铁氧体今后的研究方向及发展前景。     

超声波和微波联合辐照下铁酸锌的制备

在超声波辐照下共沉淀法得到铁酸锌前驱体,然后在微波辐照下焙烧得到脱硫剂的活性组分铁酸锌。考察了不同焙烧温度和不同焙烧时间对铁酸锌晶相和粒径的影响。实验结果表明,超声波共沉淀法制备铁酸锌是可行的,且在微波辐照下得到的铁酸锌晶相更完整、晶体粒子更为均匀,同时大大缩短了焙烧时间;在700℃下微波焙烧1 h所形成的铁酸锌能较好地满足作为脱硫剂活性组分的要求。     

Lychee-like ZnO/ZnFe2O4 core-shell hollow microsphere for improving acetone gas sensing performance

Uniformly lychee-like ZnO/ZnFe₂O₄ core-shell hollow microspheres with average size of 2.5 μm were successfully synthesized via one-step solvothermal self-assembly route. The core-shell hollow microspheres possessed mesoporous structure with a pore size of about 8.8 nm and the large specific surface area of approximately 54.0 m²/g. The effect of the Zn²⁺ concentration on the structure, morphology and gas-sensing property of the as-prepared samples were investigated by a series of testing techniques. The gas-sensing results demonstrated that the sensors based on core-shell ZnO/ZnFe₂O₄ hollow microspheres showed superior gas-sensing response, rapid response-recovery to low-ppm acetone. These excellent properties might be mainly owing to the unique core-shell structure, the large specific surface area, high concentration of oxygen vacancies and the synergetic effect between ZnO and ZnFe₂O₄. Hence, this material can be utilized as promising gas-sensing materials in the acetone detection.     

软模板水热法制备空心ZnFe2O4及吸波性能

以六水合氯化铁和氯化锌为原料,聚乙二醇4000为表面活性剂,采用软模板水热法一步合成了具有空心结构的ZnFe2O4纳米颗粒。采用XRD、XPS、FE-SEM和TEM对样品的物相和形貌进行了表征,通过振动样品磁强计（VSM）和矢量网络分析仪测试了样品的静磁性能和电磁参数,并模拟计算了样品的反射损耗,考察了其吸波性能。结果表明：所制备的ZnFe2O4粒径约为100 nm,分散均匀,具有明显的空心结构。吸波性能优异。当样品的匹配厚度为2.7 mm时,在12.41GHz处获得最小的反射损耗（-42.18dB）;而当匹配厚度为3.0mm时,样品的有效吸收带宽（反射损耗≤-10dB,即吸收率为90%）最宽,为2.60GHz（10.60~13.20GHz）。     

玻璃表面上掺杂ZnFe2O4的TiO2薄膜光催化性能的研究

采用溶胶－凝胶法在玻璃表面制备了掺杂ZnFe2O4的TiO2薄膜，通过改变ZnFe2O4的掺杂量和薄膜的热处理温度，研究了ZnFe2O4对TiO2薄膜光催化性能的影响。利用紫外光谱、SEM、XRD等测试手段指出了在TiO2薄膜中掺杂ZnFe2O4后，能较大幅度地提高TiO2薄膜的光催化活性。     

影响纳米ZnFe2O4光电催化用薄膜的因素

本文采用sol-gel法在导电玻璃上制备了纳米铁酸锌薄膜光催化剂,用差热膨胀仪对干凝胶粉的加热过程进行了分析,采用XRD、SEM等手段对制备薄膜的结构性能进行表征.结果表明：制备的纳米铁酸锌薄膜颗粒粒度均匀,平均粒径为40 nm左右.     

Preparation and electromagnetic properties of nanosized ZnFe2O4 with various shapes

In this paper, nanosized ZnFe₂O₄ with different morphologies were prepared by electrospinning method. The choice of initial parameters, such as PVP concentration, metal salt concentration, electrostatic voltage, calcination temperature and calcination rate, were investigated to prepare desired morphologies. The as-prepared samples exhibited various shapes of nano-particle, nano-rods, nano-beads and nano-fiber. The relationship between microstructure and electromagnetic properties was discussed in detail. It has been found that the saturation magnetization of ZnFe₂O₄ ferrite not changed significantly with the various morphologies and the values were nearly 13 emu/g. However, the coercivity was varied with the different morphologies, and the maximum value of 48.79 Oe was observed in the ZnFe₂O₄ nano-fiber. Moreover, the magnetic loss capacity of ZnFe₂O₄ was improved with the enhancement of the morphology anisotropy. The various shaped ZnFe₂O₄ can be promising lightweight microwave absorbers and it is significant to develop novel microwave absorption mechanism of ZnFe₂O₄ ferrite.     

Morphology controlled hydrothermal synthesis and photocatalytic properties of ZnFe2O4 nanostructures

The present work is focused on studying morphology dependent catalysis of spinel ZnFe₂O₄ nanostructures. Different morphologies i.e. porous nanorods, nanoparticles, nanoflowers and hollow microspheres were designed hydrothermally. The as prepared nanomaterials were characterized using Fourier Transform Infra-Red (FTIR), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Brunauer–Emmett–Teller (BET) technique and UV–visible spectrophotometer. The results confirmed formation of desired morphologies of cubic spinel ZnFe₂O₄ with high surface areas (92–138 m²/g) and narrow band gaps (1.76–1.97 eV). It suggested the use of ZnFe₂O₄ nanostructures as potential visible light photocatalysts. Therefore, the application of synthesized ZnFe₂O₄ nanostructures was studied in photo-Fenton degradation of dyes. The results indicated shape dependent relationship with photocatalytic activity as the degradation of dyes followed the order porous nanorods>nanoparticles>nanoflowers>hollow microspheres. The role of main active species in the reaction i.e. ^∙OH was also confirmed. All the materials exhibited stability and magnetic separability hence could act as potential photo-Fenton catalysts for wastewater treatment.