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分别用1,2和3 mol·L-1的NaOH溶液,在不同的温度条件下对坡缕石进行了侵蚀实验。对反应后的固相产物进行了XRD和SEM分析,对浸出液中的金属阳离子进行了原子吸收光谱分析。讨论了反应温度和碱溶液浓度对碱溶后产物的影响。XRD和SEM结果表明,cNaOH≤2 mol·L-1时,坡缕石经碱溶液侵蚀后,可以生成蒙脱石和方沸石,其中反应温度的升高有利于方沸石的形成,碱溶液浓度的升高有利于蒙脱石的形成。当碱溶液浓度达到3 mol·L-1,反应温度为200 ℃时,最终产物为SiO2。浸出液的定量分析结果显示,坡缕石与碱溶液的反应过程中,Na+对八面体阳离子的置换具有选择性,置换顺序为:Al3+>Fe3+(Fe2+)>Mg2+。 相似文献
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采用柱层析法、沉淀置换法和乙醇-丙酮混合溶剂法对聚合氯化铝(PAC)中的Al13形态进行了分离提纯, 采用Al-Ferron逐时络合比色法, 27Al NMR, TEM, SEM, 电位测定法, 粒度测定法等多种现代分析仪器和方法对不同分离提纯方法得到的Al13形态进行了分析表征和比较, 并初步比较研究了Al13形态的水处理效果. 实验结果表明, 不同分离纯化方法得到的 Al13形态具有不同的结构形貌、粒度分布、电性和水处理效果. 乙醇-丙酮混合溶剂法得到的Al13形态具有良好的纯度和水处理效果. 该研究初步证实了Al13是PAC中的最佳絮凝形态. 相似文献
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采用柱层析法、沉淀置换法和乙醇-丙酮混合溶剂法对聚合氯化铝(PAC)中的Al13形态进行了分离提纯, 采用Al-Ferron逐时络合比色法, 27Al NMR, TEM, SEM, 电位测定法, 粒度测定法等多种现代分析仪器和方法对不同分离提纯方法得到的Al13形态进行了分析表征和比较, 并初步比较研究了Al13形态的水处理效果. 实验结果表明, 不同分离纯化方法得到的 Al13形态具有不同的结构形貌、粒度分布、电性和水处理效果. 乙醇-丙酮混合溶剂法得到的Al13形态具有良好的纯度和水处理效果. 该研究初步证实了Al13是PAC中的最佳絮凝形态. 相似文献
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尖晶石型LiMn2O4的制备及超级电容性能研究 总被引:3,自引:0,他引:3
采用高温固相法制备LiMn2O4。X射线衍射结果表明800 ℃下得到尖晶石型LiMn2O4。利用恒流充放电、循环伏安和交流阻抗等研究了LiMn2O4电极材料在2 mol·L-1 (NH4)2SO4溶液中的超级电容性能。循环伏安测试结果表明LiMn2O4电极材料在0~1 V电位窗口范围内具有较好的方形特征;恒流充放电结果表明充放电曲线呈现出较规整的三角形对称分布,放电曲线呈直线关系,5 mA·cm-2下的放电比容量为141 F·g-1,具有较高的充放电效率,循环性能稳定;交流阻抗结果也显示LiMn2O4电极材料在2 mol·L-1 (NH4)2SO4中具有典型的电容阻抗特性。 相似文献
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不同Fe(Ⅲ)化合物与ClO-热溶液中化学反应的跟踪观察 总被引:3,自引:0,他引:3
采用分光光度法跟踪5种不同的Fe(Ⅲ)化合物分别与高碱度NaClO溶液共热到80 ℃时所发生的变化,发现Fe(Ⅲ)首先被氧化为Fe(Ⅵ);在聚合硫酸铁、六氟合铁酸钾和氢氧化铁参与的反应体系中,Fe(Ⅵ)在分解生成Fe(OH)3沉淀的同时,还有Fe(Ⅵ)紫色溶液变成Fe(Ⅳ)绿色溶液的反应存在;在硝酸铁和三氯化铁参与的反应体系中,只有Fe(Ⅵ)分解生成Fe(OH)3沉淀的反应存在。在反应过程中,聚合硫酸铁、硝酸铁所参与的反应体系中,前者生成Fe(Ⅳ)溶液浓度最高:1.25 × 10-3 mol·L-1,后者生成Fe(Ⅵ)溶液浓度最高:0.23 mol·L-1。 相似文献
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高效率变色WO3多聚体/1,10-DAD自组装薄膜的制备 总被引:1,自引:0,他引:1
A novel high-efficient photochromic self-assembly multilayered film has been fabricated from WO3 and 1,10-DAD solution using molecular deposition technique.The dependence of photochromic behavior on with WO3 in the WO3-polymer/1,10-DAD self-assembly film was discussed in comparison with WO3/4,4-BAMBp system.The results clearly show that organic molecules determine the charge density of the photo-induced charge-tracsfer complexes,andthus manipu-late the structure and the photochromic properties of the films. 相似文献
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High-temperature reactions were investigated in the MoO3-Ag2O system by means of X-ray, DTA and scanning microscopy methods, and a model was proposed according to which first an Ag2Mo4O13 phase was formed at the MoO3 and Ag2O (or metallic Ag) interface. Subsequently, at the Ag2Mo4O13-Ag2O contact area a layer of Ag2Mo2O7 appeared. If the amount of silver oxide is sufficiently high, a layer of Ag2MoO4 is formed between the Ag2O and Ag2Mo2O7 phases.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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以经典热力学第二定律ΔG<0为依据,分析了静态高温高压触媒法合成立方氮化硼(cBN)过程中发生的可能反应.考虑温度和压强对反应物相体积的影响,计算了六方氮化硼(Li3N-hBN)体系中hBN+Li3N→Li3BN2,h BN→cBN及Li3BN2→Li3N+cBN反应在高温高压条件下的ΔG.结果证实,Li3BN2由Li3N与hBN在高温高压(T>1300 K,P>3.0 GPa)条件下反应得到,在cBN的合成(T=1600~1800 K,P=4.6~6.0 GPa)条件下,hBN和Li3BN2都有向cBN转化的倾向,但由hBN向cBN直接转变的反应自由能比Li3BN2分解生成cBN的反应自由能更负,反应的可能性更大.探讨了高温高压条件下立方氮化硼的转变机理。 相似文献
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John W. C. Johns 《Mikrochimica acta》1987,93(1-6):171-188
Absolute intensities in several vibration rotation bands of CO2 and in the pure rotation spectrum of CO have been measured. The results have been used to assess the precision and accuracy which such measurements can attain when made with a high resolution Fourier transform spectrometer. 相似文献
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Microporous Silica Xerogel Membrane with High Selectivity and High Permeance for Carbon Dioxide Separation 总被引:1,自引:0,他引:1
The asymmetric microporous silica xerogel membrane was prepared by sol-gel method. A multi-layer (asymmetric) structure was obtained by silica xerogel layer on top of mesoporous silica layer (mean pore diameter of 4 nm), supported by porous alumina tube (mean pore diameter of 0.1 m). The ratio of the permeances, CO2/N2 for this membrane attained more than 60 at 298 K. This value is considerably higher than the theoretical Knudsen value (CO2/N2 = 0.8). The gas permeances of this membrane were about 5–10 times higher than the previous membrane. Application of the membrane to an enrichment of CO2 from air was also investigated. CO2 in the air (about 300 ppm) was concentrated to more than 1000 ppm by using the membrane at 298 K. 相似文献
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High Photocatalytic Activity of F-Doped TiO2 Film on Glass 总被引:7,自引:0,他引:7
The photoreactivity of sol-gel (SG)-TiO2 films was enhanced significantly with addition of a small amount of trifluoroacetic acid (TFA) into the starting solution. The promoting effect was confirmed in two separate experiments of the methylsiloxane monolayer oxidation and the photocurrent measurements. The results of film characterization indicated that the absorption coefficient for ultraviolet light ( < 360 nm) increases due to film densification and the crystallinity is improved upon F doping. The improvement in the photoreactivity was ultimately attributed to the increase in the rate at which the photogenerated charge carriers reach the surface in the photostationary state. 相似文献
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《Analytical letters》2012,45(6):681-693
Abstract A practical and correct methodology for evaluating CH2O in air without sampling artifact formation is presented. Formaldehyde is collected on an annular denuder coated with bisulfite-triethanolamine. The sorbent layer is extracted with water and the solution analyzed by the chromotropic acid (CTA) procedure. Sorption efficiency and loading capacity have been investigated along with storage stability. Results of laboratory validation studies have indicated that a small annular denuder was able to sample about 300 μg CH2O without an appreciable decrease in the initial collection efficiency (99% at 2.5 1 min?1). Tests on storage stability before and after exposure have also demonstrated that both oxidation of bisulfite and release of CH2O did not occur for time periods as long as 1 month. 相似文献
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Pure SnO2, sulfated SnO2-SO4
2- and Pd supported on SnO2 and SnO2-SO4
2- were prepared from SnO2 precursor with high surface area, and used for CH4 deep oxidation. The catalysts were characterized by means of N2-BET, XRD, TG-DTA, XPS and TPD. SnO2-SO4
2- shows higher activity than SnO2, due to the presence of more active oxygen species, superacid sites and its higher BET surface area. Pd/SnO2 and Pd/SnO2-SO4
2- display essentially the same activity to each other, while it is much higher than the activity on SnO2 and SnO2-SO4
2-. The main reason is ascribed to the concerted action between Pd and the supports. 相似文献
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Shi‐Zhao Kang Zhizhen Xu Yixin Song 《Journal of Dispersion Science and Technology》2013,34(6):857-859
In this article, TiO2 nanorods (aspect ratio >20) were prepared through a polyol process and doped with metal ions (Cu2+, Ni2+, Fe3+, and Cr3+). Compared with TiO2 nanoparticles, the TiO2 nanorods displayed relatively higher photocatalytic activity for the degradation of copper sulfophthalocyanine. Moreover, the photocatalytic activity was greatly enhanced when the metal ions were doped in the TiO2 nanorods. 相似文献
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Shujie You Zhi Li Liuxiang Yang Cheng Dong Liangcheng Chen Changqing Jin Jingzhu Hu Guoyin Shen Hokwang Mao 《Journal of solid state chemistry》2009,182(11):3085-3090
Using diamond anvil cell technique with angle dispersive X-ray diffraction (ADXD) of synchrotron radiation and electrical conductivity measurements, we have observed that CuO2 chain compound Li2CuO2 transforms from ambient orthorhombic symmetry into a new phase at above 5.4 GPa and room temperature. The new phase was found to be of monoclinic structure with an increased oxygen coordination number of Cu2+ from four at ambient to six at high pressure that provides a structural basis of the evolution of principle physical properties. The high pressure phase of Li2CuO2 is discussed in line with the first principle calculations. 相似文献