聚乙二醇-硫酸铵萃取铬(Ⅵ)-二苯偶氮羰酰肼的研究与应用

Study on Extraction Separation System of Chromium(Ⅵ)diphenylcarbazone polyethylene Glycol ammonium Sulfate and Its Analytical Application

研究了铬 ( ) -二苯偶氮羰酰肼 (DPCO) -聚乙二醇 (PEG)体系的萃取行为和分相条件 ,建立了非有机溶剂萃取光度法测定微量铬的新方法。在p H2 .0的 KCl-HCl缓冲溶液中 ,硫酸铵存在下 ,Cr( ) -DPCO配合物可被PEG相完全萃取 ,而 Fe( )、Al( )、V( )、W( )、Mo( )、Sn( )等基本不被萃取。在 PEG相中 ,配合物的最大吸收波长为 5 5 0 nm,表观摩尔吸光系数为 6 .75× 10 4L·mol-1·cm-1。铬含量在 0～ 2 5 μg/10 m L 范围内服从比尔定律。 PEG相中铬 ( )与二苯偶氮羰酰肼形成组成比为 n Cr∶ n DPCO=1∶ 3的络阳离子。研究了不同表面活性剂对 PEG萃取行为的影响。

A new method for nonN organic solvent extraction and spectrophotometric determination of chromium by the system of chromium (Ⅵ) diphenylcarbazone (DPCO) polyethylene glycol(PEG) ammonium sulfate was developed.The extraction behavior based on the Cr(Ⅵ) DPCO PEG system in the presence of ammonium sulfate and optimum conditions of phase separation of PEG and water was investigated.In pH 2.0 KCl HCl buffer solution,the complex of Cr(Ⅵ) DPCO can be extracted by PEG (NH 4) 2SO 4,but Fe 3+ 、Al 3+ 、V(Ⅴ)、W(Ⅵ)、Mo(Ⅵ) can not be extracted.The maximum absorption of the complex in PEG is at 550 nm with an apparent molar absorptivity of 6.75×104 L·mol -1 ·cm -1 .Beer′s law is obeyed in the range of 0～25 μg/10 mL for chromium.Experimental result shows that the complex has a molar ratio of Cr∶DPCO=1∶3 in PEG phase.The extraction mechanism for PEG phase was studied by the addition of different surface active agents.The method was applied to quantitative separation and determination of trace chromium in water.