用火焰原子吸收法测定铬酸盐转化膜中的Cr(Ⅵ)和Cr(Ⅲ)

Determination of Cr(VI) and Cr(Ⅲ) in Passivation Film of Chromate by Flame Atomic Absorption Spectroscopy Combined with Separation and Concentration Using Humic Acid Resin

为研究铬酸盐转化膜中Cr(Ⅵ)和Cr(Ⅲ)测定的新方法,用酚醛树脂对腐植酸交联固化,制备了颗粒状腐植酸吸附树脂;以火焰原子吸收法为检测手段,研究了该树脂对Cr(Ⅵ)和Cr(Ⅲ)的分离富集性能。用火焰原子吸收分光光度法进行测定,从而建立了腐植酸树脂分离富集、火焰原子吸收法测定铬形态的新方法,用于铬酸盐转化膜中Cr(Ⅵ)和Cr(Ⅲ)含量的测定,结果满意。

The method for the determination of Cr(VI) and Cr(Ⅲ) in the passivation film of chromate was studied.Thus humic acid resin powders were prepared by cross-linking of humic acid in the presence of phenolic resin.The adsorption characteristics and separation and concentration of Cr(VI) and Cr(Ⅲ) by the humic acid resin were investigated by means of flame atomic absorption spectrometry(FAAS).The results showed that Cr(Ⅵ) could be quantitatively adsorbed by the humic acid resin at a pH value below 1,when Cr(Ⅲ) could not be adsorbed.At a pH value above 5,Cr(Ⅲ) could be adsorbed,but Cr(Ⅵ) could not be adsorbed.Therefore,it was feasible to separate Cr(Ⅵ) and Cr(Ⅲ) by adjusting the pH value of the medium.Namely,Cr(Ⅵ) and Cr(Ⅲ) adsorbed on the humic acid resin could be completely eluted using 0.5 mol/L NaOH and 1 mol/L HCl solution,respectively.Then Cr(Ⅵ) and Cr(Ⅲ) could be determined using FAAS.The corresponding newly established method could be satisfactorily applied for the determination of Cr(Ⅵ) and Cr(Ⅲ) in the passivation film of chromate.