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钒的停流──诱导光度法测定及价态分析 总被引:1,自引:1,他引:1
依据V~(4+)对Cr~(6+-)I~-氧化还原反应的诱导作用,建立了微量V~(4+)的停流—动力学光度测定方法。方法的线性范围为0~2.1mg·l~(-1):最低检测浓度为0.008mg·l~(-1)。10倍量的V~(5+)不影响测定。测得V~(4+)后,还原V~(5+)为V~(4+),测定总钒量,进而对钒进行价态分析。 相似文献
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选用化合物分子拓扑学的信息理论指数、价分子连接性指数,运用多元非线性回归分析,对114种有机磷农药大鼠经口、小鼠经口及大鼠经皮急性毒性LD50、神经毒性作用进行了定量预测分析。回归模型相关指数R^2均在0.81以上,残差呈正态分布,预测效果满意,显示了系统具有较强的预测能力。 相似文献
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Huijun He Yan Cheng Chunping Yang Guangming Zeng Canyao Zhu Zhou Yan 《环境科学学报(英文版)》2017,29(4):135-141
Dispersion and aggregation of nanoparticles in aqueous solutions are important factors for safe application of nanoparticles. In this study, dispersion and aggregation of nano-TiO2 in aqueous solutions containing various anions were investigated. The influences of anion concentration and valence on the aggregation size, zeta potential and aggregation kinetics were individually investigated. Results showed that the zeta potential decreased from 19.8 to − 41.4 mV when PO43 − concentration was increased from 0 to 50 mg/L, while the corresponding average size of nano-TiO2 particles decreased from 613.2 to 540.3 nm. Both SO42 − and NO3− enhanced aggregation of nano-TiO2 in solution. As SO42 − concentration was increased from 0 to 500 mg/L, the zeta potential decreased from 19.8 to 1.4 mV, and aggregate sizes increased from 613.2 to 961.3 nm. The trend for NO3− fluctuation was similar to that for SO42 − although the range of variation for NO3− was relatively narrow. SO42 − and NO3− accelerated the aggregation rapidly, while PO43 − did so slowly. These findings facilitate the understanding of aggregation and dispersion mechanisms of nano-TiO2 in aqueous solutions in the presence of anions of interest. 相似文献
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