Abstract

An extractant forced-circulation three-phase extraction (EC-TPE) device based on extraction-stripping coupling was developed for the preconcentration of Cd²⁺ in environmental samples. In this three-phase extraction (W₁/O↔O/W₂) system, Cd²⁺ in the sample solution (W₁) was fully extracted into the stripping phase (W₂) by the circular flow of an organic phase (O↔O). The extraction yield (EY) and enrichment factor (EF) reached almost 100% and 100, respectively, under the following operating conditions: 0.1 M HNO₃, 2 mL/L di(2-ethylhexyl)phosphoric acid (P204), circulation flow rate of 32 mL/min, circulation time of 45 min and stirring speed of 400 rpm. An extraction yield of more than 98.5% was still achieved after reusing the organic phase eight times. Two theoretical formulas were established for predicting the EY and EF. Thereafter, EC-TPE was applied in the preconcentration of ppb-level Cd²⁺ for flame atomic absorption spectrophotometer assay with a detection limit of 0.17 μg/L. Addition/recovery tests for Cd²⁺ were carried out with recoveries exceeding 98%, and three environmental water samples were accurately analyzed. Finally, application of the EC-TPE device was extended to a different extraction system and other metal ions: Zn²⁺, Cu²⁺, Ni²⁺, and Co²⁺. The EC-TPE device is easily established utilizing common laboratory glassware, and the enrichment operation efficiency can be conveniently improved by using more than one device simultaneously.

摘要

开发了一种基于萃取-汽提耦合的萃取剂强制循环三相萃取（EC-TPE）装置，用于对环境样品中的Cd ²⁺进行预富集。在该三相萃取（W ₁ /O↔O/ W ₂）系统中，样品溶液（W ₁）中的Cd ²⁺通过有机相（C ₂）的循环流（W ₂）被完全萃取到汽提相（W ₂）中。 O↔O）。提取产率（EY）和富集因子（EF）几乎达到100％和100，分别为在以下操作条件下：0.1M HNO ₃，2 mL / L二（2-乙基己基）磷酸（P204），循环流速为32 mL / min，循环时间为45 min，搅拌速度为400 rpm。将有机相重复使用八次后，萃取率仍达到98.5％以上。建立了两种预测EY和EF的理论公式。此后，将EC-TPE应用于ppb级Cd ²⁺的预浓缩，用于火焰原子吸收分光光度计测定，检测极限为0.17μg/ L。进行了Cd ^2+的添加/回收试验，回收率超过98％，并且对三个环境水样品进行了精确分析。最终，将EC-TPE装置的应用扩展到了不同的萃取系统和其他金属离子：Zn²⁺，Cu 2 ⁺，Ni ²⁺和Co ²⁺。使用常见的实验室玻璃器皿可以轻松建立EC-TPE设备，同时使用多个设备可以方便地提高浓缩操作效率。