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《Chemie der Erde / Geochemistry》2014,74(4):653-660
This work demonstrates that a Fe-exchanged zeolitic volcanic tuff from Cepari (Fe/CV) (Bistrita-Nasaud County, Romania) is suitable for the amperometric detection of H2O2, using new modified carbon paste electrodes based on this material (Fe/CV-CPEs). The physical-chemical characterization of natural (CV) and modified (Fe/CV) forms was realized using chemical analysis, optical microscopy, scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), energy dispersive X-ray spectroscopy (EDX) and Fourier transformed infrared (FTIR) spectroscopy. The resulting electrodes (Fe/CV-CPEs) were investigated using cyclic voltammetry and chronoamperometry measurements. The new electrodes showed good electrocatalytic activity toward H2O2 reduction. The calibration curve for H2O2 determination was linear up to 0.1 mM, with a detection limit (signal to noise ratio of 3) of 20 μM. 相似文献
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地电场方法在川滇地区地震观测中的应用 总被引:1,自引:0,他引:1
利用云南省(5个)和四川省(4个)"十五"期间布设的地电场观测数据,利用大地电场观测系统中,同一测向长短极距测值的比值方法进行分析,发现能够较好地排除来自大地电场及自然电场远场的变化信息,突出可识别的地震前兆异常信息。研究结果表明:在剔除各种环境和空间电流体系的影响因素后,提取了与地震有关的异常信息,在川滇地区5.0级地震前,多数台站的地电场观测资料比值发生异常变化,异常大多出现在地震前0.5—3个月,其中汶川地震和姚安地震前,研究区的9个台站均出现异常。 相似文献
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长周期大地电磁测深需要观测最长周期为几万秒的大地电磁场信号,这要求用于测量电场信号的不极化电极具有很小的极差,以及至少长达1—2个月的稳定时间,普通的不极化电极不能满足要求。通过改进电极电解质配方和电极结构,试制出铅-氯化铅不极化电极。测量结果表明,该电极具有极差小、稳定时间长、使用寿命长、维护简单等优良特性。在山东菏泽等地的野外实验表明,该类不极化电极能够很好地观测几万秒的长周期信号。同等条件下,其性能优于国外同类产品,达到预期目标。 相似文献
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Magne Ødegård Øyvind Skår Henrik Schiellerup Norman J. Pearson 《Geostandards and Geoanalytical Research》2005,29(2):197-209
This paper describes a technique for the preparation of a titanite (CaTiSiO5 ) glass calibration material for use in in situ microanalysis of major, minor, and trace elements in geological materials. The starting composition was a titanite matrix doped with minor and trace elements at ∼ 200 μg g-1 . The elements Sc, Y, REEs, Th and U were added in the form of nitrates in solution, and the elements V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Hf and W were added as solid oxides. The synthetic titanite glass was produced by direct fusion by resistance heating in graphite electrodes at 1600-1700 °C, and quenched in air. Backscattered electron images indicate good homogeneity, with no signs of separate phases or vesicles, and analysis of the major elements Ca, Ti and Si by electron microprobe showed relative standard deviations between 0.5 and 0.7%, based on six independent measurements. Deviations from nominal concentrations for Ca, Si and Ti were measured to -1.2, -3.3 and -0.8%, respectively. The homogeneity of the trace elements in the glass was assessed by LA-ICP-MS analyses, using NIST SRM 610, 612 and 616 as external calibrators, and Ca as the internal standard element. Determinations were made both with a quadrupole mass spectrometer and a sector field instrument, and both raster and spot modes of analysis were used. For the majority of doped elements, precision was better than 10%, and relative deviations from nominal values were, with few exceptions, between 5 and 10%. 相似文献
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The electrogenerative removal of cobalt is conducted in a batch reactor equipped with three‐dimensional electrodes: Reticulated vitreous carbon (RVC) and porous graphite (PG‐25) as cathode materials. In this process, a chemical reaction takes place spontaneously in a divided cell where cobalt is reduced at the cathode and zinc is oxidized to produce electrical energy without an external supply of energy. The results obtained show that RVC serves as a more suitable cathode material than PG‐25 in this system. At optimum conditions, more than 99% of cobalt were removed and recovered in its metallic state after 10 h of operation with an initial 200 mg L?1 Co(II) solution at pH 4 in 0.2 M Na2SO4 and 0.4 M boric acid. Scanning electron microscopy and X‐ray diffraction analyses are performed to study the morphology and crystallographic patterns of cobalt deposits on the cathodes, respectively. 相似文献
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地电阻率多极距观测中的最佳布极方式 总被引:2,自引:0,他引:2
对如何确定地电阻率多极距观测中的最佳布极方式, 包括极距个数和各极距长度的确定进行了研究。 确定最佳布极方式的主要依据是地下各层介质的响应系数随观测极距的变化规律以及采用不同观测极距对反演精度的影响。 以宝坻台为例, 讨论了在电性剖面参数已知的情况下, 如何确定多极距观测中各极距长度。 最后, 利用提出的最佳布极方式确定的装置系统对宝坻台模拟多极距观测资料进行了处理。 结果表明, 用最佳布极方式确定的多极距观测系统可精确计算出地下各层介质的真电阻率变化。 相似文献