共查询到17条相似文献，搜索用时 656 毫秒
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以木屑为原料,高温热解制备生物炭。以聚乙烯醇为粘结剂,采用混合法将生物炭与果胶复合,并负载磁性,经烘干定型制备果胶包覆的磁性生物炭材料（果胶@生物炭-Fe3O4）。采用扫描电镜（SEM）、X射线衍射（XRD）及N2吸附-脱附（BET）等方法对果胶@生物炭-Fe3O4进行表征,结合吸附实验分析其对Cu2+的吸附特性。结果表明,当生物炭、果胶、Fe3O4质量比为5：1：1,溶液pH值为6,吸附24 h,果胶@生物炭-Fe3O4对Cu2+吸附效果最好;二级动力学方程能较好地描述果胶@生物炭-Fe3O4对Cu2+的吸附过程,Freundlich模型能较好地拟合其吸附行为;SEM结果显示该材料具有不规则的孔隙结构;XRD分析显示纳米Fe3O4是其主要的晶体结构;BET测得其比表面积为25.654 m2·g-1,平均孔径为20.18 nm。 相似文献
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文章基于密度泛函理论,研究了本征及Nb,Fe单原子掺杂单层MoSe2的电子结构及光学性质。计算发现,本征单层MoSe2和Nb-MoSe2为直接带隙半导体,Fe-MoSe2为间接带隙结构;Fe-MoSe2较本征单层MoSe2导电性大大提高,实现了由半导体向半金属的过渡。由态密度分析得出了本征及Nb,Fe单原子掺杂单层MoSe2能量状态主要由Mo 4d,Se 4p轨道电子所贡献的结论,并对各原子掺杂体系轨道电子的能量贡献和掺杂类型做了探讨。此外,还详细分析了费米能级附近的自旋态密度、杂质带、磁性之间的联系。光学性质方面,比较了本征单层MoSe2与各掺杂体系的复介电常数和光吸收系数,在红外光区Fe-MoSe2的吸收系数高于本征单层MoSe2。本征单层MoSe2的光吸收系数为9.69×104 cm-1,是区域最大吸收峰。上述研究表明,通过对单层MoSe2的Nb,Fe掺杂可使电子输运特性得到了增强,为高活性自旋电子和光电子器件设计和研究开辟了新的前景。 相似文献
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研究以玉米秸秆为原料制备生物质活性炭,并分别进行NaOH和HNO3改性。考察三种生物质活性炭的用量和粒径、水溶液pH值和吸附时间对水溶液中Cu2+吸附性能的影响,并对其等温吸附特征、吸附动力学和吸附热力学进行研究。结果表明:当0.15~0.30mm的生物质活性炭投加量为0.30g,pH值为6.0时,对溶液中Cu2+具有很好的去除率,在360min时达到吸附平衡;吸附过程符合Langmuir和Freundlich模型以及准二级动力学方程,且热力学参数ΔG0＜0,ΔH0和ΔS0＞0,为自发的、吸热的和熵增的过程,对水溶液中Cu2+均具有较好的亲和力;相同条件下,三种生物质活性炭对Cu2+的吸附效果表现为:NaOH改性＞HNO3改性＞未改性。 相似文献
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本研究采用共沉淀法和水热法成功制备出Z型异质结BiVO4/g-C3N4光催化剂。通过X射线衍射(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)和紫外-可见漫反射光谱(UV-vis DRS)方法对制备的样品进行了结构、形貌和光电化学性能表征,并对其可能的光催化反应机理进行了探讨。研究结果表明：与单一的BiVO4、g-C3N4光催化剂相比,Z型异质结BiVO4/g-C3N4光催化剂在可见光下对亚甲基蓝(MB)的降解具有最高的活性,分别是单一的BiVO4和g-C3N4的12倍和2.18倍。经过5次循环实验测试,Z型异质结BiVO4/g-C3N4光催化剂对亚甲基蓝MB的降解率均能达到90%,证明其有良好的稳定性。此外,通过活性物种捕获实验对Z型异质结B... 相似文献
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以铁尾矿砂为原料,用NaOH,HNO3调节pH值,采用熔融-水热两步法制备了铁尾矿砂光催化剂。利用X射线衍射仪、紫外/可见/近红外光谱仪等对铁尾矿砂光催化剂的结构性能进行表征;以罗丹明B溶液为标准降解物,汞灯为光源,探讨在不同pH条件下合成的铁尾矿砂光催化剂的光催化活性。结果表明,铁尾矿砂光催化剂的主要成分为Fe2.35Si0.65O4和NaNO3,且具有良好的光催化效果;在pH 8.5条件下制备的样品具有多孔结构,光催化性能最强;光照120 min时此样品可降解95.1%的罗丹明B溶液;·O2-是光催化反应过程中最主要的氧化活性自由基。 相似文献
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在纯净空气与H2O/ CO2污染空气来流对比试验结果基础上,采用数值计算方法和化学动力学方法,研究了H2O和CO2污染组分对煤油燃料超声速燃烧的影响,获得了试验手段难以得到的燃烧室流场参数和性能数据。完成了相应的煤油燃料超声速燃烧室二维数值计算,其中匹配了进口总温、总压、马赫数、氧气摩尔分数和工作当量油气比。将数值计算结果与相应试验测量值进行了对比分析,并结合燃烧室流场数据、性能参数分析了H2O和CO2污染的动力学影响、以及对燃烧室性能的影响。研究表明:(1)数值计算结果与实验测量值总体上吻合,两种手段均体现了纯净空气来流时不同煤油当量油气比的燃烧室性能,并反映了一致的“污染效应”影响趋势;(2) H2O污染、H2O+ CO2污染的存在降低了煤油燃料超声速燃烧室性能,体现在燃烧诱导压升、燃烧效率、流向冲量增量的下降,而且随着污染组分含量的增加,燃烧室性能下降越加显著。 相似文献
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利用化学共沉淀法制备了磁性Fe3O4纳米微粒,用硅烷偶联剂MPS对所制备的磁性微粒进行表面有机改性,并用FTIR、XRD、TEM、XPS等表征方法对样品进行了表征,结果表明:MPS已经很好地键连到了磁性Fe3O4纳米微粒的表面。改性的磁性Fe3O4纳米微粒具有亲水和亲油两种性质,采用改性后的磁性微粒可以显著改善磁性微球的性能指标。 相似文献
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采用微波加热合成离子液体[Bmim]BF4,以该离子液体为反应介质,在微波辐射条件下制备TiO2光催化剂,在高压汞灯下用甲基橙溶液测试其光催化降解性能;并用XRD,IR,TG对其进行测试和表征。结果表明,制备TiO2光催化剂的较佳条件是:离子液体2.0mL,微波辐射功率600W、反应温度70℃、反应时间35min。并且用[Bmim]BF4作为反应介质,能够显著提高TiO2的光催化活性,所制备的TiO2不需要经过高温煅烧,就表现出极高的光催化活性。该催化剂对甲基橙的降解率在1.5h就可达到93.7%。 相似文献
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Ba0.6Sr0.4TiO3 （BST） thin films with and without HfO 2 buffer layer were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. Dependences of HfO 2 thickness on the dielectric property and leakage current of BST thin films were focused. The dielectric constant of BST thin films increased and then decreased with the increase of HfO 2 thickness, while the dielectric relaxation was gradually improved. The loss tangent and leakage current under positive bias decreased with the HfO 2 thickness increasing. The leakage current analysis based on the Schottky emission indicated an improvement of the BST/Pt interface with HfO 2 buffer layer. The loss tangent, tunability and figure of merit of optimized HfO 2 buffered BST thin film achieved 0.009 8, 21.91% （E max = 200 kV/cm）, 22.40 at 10 6 Hz, respectively. 相似文献
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Xian-jin Yu Ph. D. Guang-li Zhang Zhu-xian Qiu Min-shou Zhao Qiang Su 《上海大学学报(英文版)》1999,3(3):251-254
ZnFe2O4 and ZnFe2O4-based materials were tested to obtain the electrical conductivity and corrosion resistance in melting bath for aluminum electrolysis.
The results proved that adequate additives, such as Ni2O3 CuO, Cu, ZnO and CeO2 would increase the electrical conductivity, and the ZnFe2O4-based anodes with these additives were of good corrosion resistance. The current density on anode, the mole ratio of NaF/AlF3 (MR) and the content of alumina in the bath effect the anode corrosion rate in different way.
Project supported by the Science Foundation of Liaoning Province, P. R. China (95 – 156) 相似文献
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(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980-1 030 ℃ were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d33 was measured using a quasi-static piezoelectric d33 meter. The planar coupling coefficient Kp was calculated by resonance-antiresonance method. The experimental data for each sample's performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K0.47Na0.47Li0.06)NbO3 prepared by MSS is compact and lead-free. The piezoelectric constant d33 is 216 pC·N-1 and the planar electromechanical coupling factor Kp is 0.352. 相似文献
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利用EF-H_2O_2-FeO_X法深度处理畜牧业养殖废水,结果表明,当pH值为3,电压为24 V,反应时间为45 min,电解质投加量为0.8 g/L,PAM投加量为2.5 mg/L时,对畜牧业养殖废水的深度处理效果最佳,COD的去除率可以达到99.1%。此方法具有成本低、设备简单、效果好等优点,在畜牧业养殖废水的深度处理领域具有广阔的应用前景。 相似文献
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This work investigated the microwave dielectric properties of A-site substitution by rare earth La3+in(Pb0.5Ca0.5)(Fe0.5Ta0.5)O3(PCFT) system.A single perovskite phase was obtained only when the doping content was 2%.Suitable La3+ doping improved microwave dielectric performances.Excessive La3+doping caused the formation of secondary phase,which resulted in the decreasing of permittivity εrand quality factor Qfvalues.Especially,when the doping content is 2%-5%,permittivity εrwas above 75 and Qfvalues were 6... 相似文献
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Chemically processed Nb-doped SrTiO3 films and properties 总被引：1，自引：0，他引：1
Ming-zhi Yin 《浙江大学学报(A卷英文版)》2006,7(8):1436-1439
Homogeneous, crack-free SrNbxTi1−x
O3 thin films on (110) silicon substrates were successfully fabricated by sol-gel processing. The optimum route and conditions
were systematically investigated. Sr(OAc)2 glacial acctic acid solution, after being refluxed and reacted with tartrate, formed Sr(OAc)2(C4H6O6)2; Ti(OBu)4 formed Ti(OAc)4−x
(AcAc)x after having the ligand partially exchanged with AcAc, while Nb(OC2H5)5 formed (OAc)2Nb(AcAc) (C4H6O6) by exchanging of ligand in glacial acetic acid with (CH3CO)2O. All the metal species after undergoing partial hydrolysis and polymerization with hydroxyl or oxygen, formed SrNbxTi1−x
O13 cluster sol. Methyl cellulose (MCL) caused SrNbxTi1−x
O3 sol to have polymeric structure and easily form films. SrNbxTi1−x
O3 films with perovskite were subsequently formed after being annealed at 650∼750 °C for 60 min in 25% N2+75% H2 (volume ratio) atmosphere. Resistivity of the SrNb0.1Ti0.9O3 films at room temperature was 64 μω·cm, a particular T
2 temperature dependence of the resistivity, from 25 K up to room temperature, was observed.
Project (No. 2002CB613305) supported by the National Basic Research Program (973) of China 相似文献
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Dong-dong Cao Jin Hu Xin-xian Huang Xian-ju Wang Ya-jing Guan Zhou-fei Wang 《Journal of Zhejiang University. Science. B》2008,9(12):964-968
The changes of kernel nutritive components and seed vigor in F1 seeds of sh
2 sweet corn during seed development stage were investigated and the relationships between them were analyzed by time series
regression (TSR) analysis. The results show that total soluble sugar and reducing sugar contents gradually declined, while
starch and soluble protein contents increased throughout the seed development stages. Germination percentage, energy of germination,
germination index and vigor index gradually increased along with seed development and reached the highest levels at 38 d after
pollination (DAP). The TSR showed that, during 14 to 42 DAP, total soluble sugar content was independent of the vigor parameters
determined in present experiment, while the reducing sugar content had a significant effect on seed vigor. TSR equations between
seed reducing sugar and seed vigor were also developed. There were negative correlations between the seed reducing sugar content
and the germination percentage, energy of germination, germination index and vigor index, respectively. It is suggested that
the seed germination, energy of germination, germination index and vigor index could be predicted by the content of reducing
sugar in sweet corn seeds during seed development stages.
Project supported by the National Natural Science Foundation of China (No. 30370911) and Education Department of Zhejiang
Province, China (No. 20070147) 相似文献