A Simple Analytical Method for Monitoring the Total Concentration of Heavy Metal Ions in Environmental Waters

Abstract

A non-sophisticated analytical procedure has been developed for monitoring the sum of heavy metal elements which form stronger EDTA complexes than manganese(II). It is based on complexation of the heavy metals with EDTA and a catalytic indication of its stoichiometry. The equivalence point is determined visually using the substitution reaction between Mn(II)-EDTA and heavy metal ions, followed by the Mn(II)-catalyzed oxidation of Acid Blue 45 dye with hydrogen peroxide. The method has a reasonable accuracy, uses simple test equipment and stable reagents, there are few interferences and it can be carried out by non-technical personnel. Neither preconcentration nor dilution of the sample is required and it is applicable to aqueous samples containing heavy metals down to ppm levels. Some applications to river and groundwaters are shown.     

B对人造金刚石表面结构及性能的影响

研究了B对人造金刚石表面结构及性能的影响。结果表明,采用渗B石墨或渗B触媒合成的金刚石,表面存在有螺旋状和阶梯状生长台阶,树枝状和河流状结晶等。但对金刚石性能影响不大。含B金刚石的性能明显优于不含B金刚石。且渗B石墨对金刚石性能的影响比渗B触媒大。     

乌鲁木齐河年最大流量的混沌特征研究

本文利用乌鲁木齐河年最大洪水流量的时间序列．从吸引子的关联维数分析了32年来乌鲁木齐河年最大洪水流量变化的混沌性质及其特征．对认识该系统的特征提供了更多有意义的信息．