强碱性阴离子交换纤维萃取分离-电感耦合等离子体原子发射光谱法测定再生锌中铅和镉

使用电感耦合等离子体原子发射光谱法(ICP-AES)直接测定再生锌中铅和镉时,锌和铁等共存元素会对测定产生干扰。当待测液中锌含量分别大于铅和镉含量的20倍时, 直接测定铅和镉结果的相对误差均大于5%,而再生锌中锌相对铅和镉的含量远高于此倍数。研究表明,在I^-存在下, 再生锌样品中的Pb²⁺和Cd²⁺分别形成具有8-羟基喹啉螯合物结构的PbI^2-₄和CdI^2-₄络阴离子,此时Zn²⁺、Fe²⁺和Ca²⁺等阳离子不形成碘络阴离子。以强碱性阴离子交换纤维(SBAEF)萃取溶液中的PbI^2-₄和CdI^2-₄,SBAEF能特异性吸附8-羟基喹啉螯合物PbI^2-₄和CdI^2-₄,使铅、镉与锌、铁、钙等干扰元素分离, 再用一定浓度的EDTA溶液将PbI^2-₄和CdI^2-₄同时洗脱,然后使用ICP-AES测定,从而建立了再生锌中铅和镉的测定方法。方法有效地消除了锌、铁等共存元素对测定的干扰,测定范围为:0.10%≤w_Pb≤10.00%;0.050%≤w_Cd≤5.00%。方法应用于实际再生锌样品中铅和镉的测定,结果的相对标准偏差(RSD,n=5)为0.89%~1.7%,回收率为99%~101%。采用实验方法测定与再生锌成分相似的锌精矿标准样品中铅和镉,测定结果与认定值相吻合;采用实验方法测定再生锌模拟液,铅和镉的回收率为97%~104%。

Determination of lead and cadmium in regenerated zinc by inductively coupled plasma atomic emission spectrometry after extraction separation with strongly basic anion exchange fiber

During the direct determination of lead and cadmium in regenerated zinc by inductively coupled plasma atomic emission spectrometry (ICP-AES), the coexisting elements such as zinc and iron would cause interference. When the content of zinc in testing solution was 20 times higher than that of lead and cadmium, the relative error of both lead and cadmium by direct determination was higher than 5%. In fact, the content of zinc in regenerated zinc was much higher than this fold compared to lead and cadmium. In presence of I^-, it was found that Pb²⁺ and Cd²⁺ in regenerated zinc sample could form PbI^2-₄ and CdI^2-₄ complex anions with the structure of 8-hydroxyquinoline chelate. Meanwhile, the cations such as Zn²⁺, Fe²⁺ and Ca²⁺ would not react with I^- to form complex anions. PbI^2-₄ and CdI^2-₄ in solution were extracted with strongly basic anion exchange fiber (SBAEF). SBAEF could specifically absorb 8-hydroxyquinoline chelates (PbI^2-₄ and CdI^2-₄), realizing the separation of lead and cadmium from interference elements including zinc, iron and calcium. Then PbI^2-₄ and CdI^2-₄ were simultaneously eluted with EDTA solution for the determination by ICP-AES. Thus the determination method of lead and cadmium in regenerated zinc was established. The proposed method could effectively eliminate the interference of coexisting elements such as zinc and iron. The determination range was 0.10%≤w_Pb≤10.00% and 0.050%≤w_Cd≤5.00%. The proposed method was applied to the determination of lead and cadmium in actual samples of regenerated zinc. The relative standard deviations (RSD, n=5) of determination methods were between 0.89% and 1.7%, and the recoveries were between 99% and 101%. The contents of lead and cadmium in certified reference material of zinc concentrate with similar composition to regenerated zinc were determined according to the experimental method. The found results were consistent with the certified values. The simulated solution of regenerated zinc was determined according to the experimental method. The recoveries of lead and cadmium were between 97% and 104%.