Determination of Chromium (Ⅵ) by Diphenylcarbohydrazide Spectrophotometry:Disadvantages and Improvement
ZHANG Kai-Ge, WANG Yun-He, LI Shuang-Ying, FAN Jing
School of Environment, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Xinxiang 453007, China
Abstract The determination of toxic heavy metal chromium (Ⅵ) is an important experiment content in the majors of environment, chemistry and etc. As national standard method, the 1,5-diphenylcarbohydrazide spectrophotometry (GB/T 7467-1987) is usually used. However, this national method has some disadvantages of using volatile toxic solvent, cumbersome operation and unfriendliness to the environment and operator. In the improved method, the diphenylcarbohydrazide chromogenic agent was prepared by using ethanol instead of toxic acetone as the solvent. Moreover, hydrochloric acid was instead of the mixed acid of sulphuric acid and phosphoric acid, which was then directly added to the chromogenic agent. This improved method simplified the operation step, improved work efficiency and reduced environmental and health damage. To evaluate accuracy of the proposed method, the concentration of chromium (Ⅵ) in wastewater samples was simultaneously determined by the atomic absorption spectroscopy method. The results showed that there was no significant difference between the two methods.
ZHANG Kai-Ge, WANG Yun-He, LI Shuang-Ying, FAN Jing. Determination of Chromium (Ⅵ) by Diphenylcarbohydrazide Spectrophotometry:Disadvantages and Improvement[J]. Chinese Journal of Chemical Education, 2019, 40(14): 49-52.
