Application of surface-active ionic liquids in micelle-mediated extraction methods: pre-concentration of cadmium ions by surface-active ionic liquid-assisted cloud point extraction

Abstract

In this work, a modified cloud point extraction method based on the micellar features of a surface-active ionic liquid (SAIL) was developed. Mixture of a nonionic surfactant (Triton X-114) and a surface-active ionic liquid, 1-hexadecyl-3-methylimidazolium chloride (C16MeImCl), was used as an extracting phase for pre-concentration of cadmium ions prior to the determination by flame atomic absorption spectrometry. According to the obtained results, by using this route, the extraction efficiency of the investigated analyte was improved. On the other hand, more reproducible measurements were established. These features could be attributed to the enhancement effect of the SAIL on the extraction efficiency and its influence on the completeness and ease of separation of the extracting phase from the aqueous phase at the last step of the extraction process. Comparison of the obtained results against those acquired by using the same procedure in the absence of SAIL showed the advantages of the proposed method. Under the optimal conditions, the calibration curve of Cd2+ was linear in the range of 1–500 μg L−1 with correlation coefficient of 0.9999 and a detection limit of 0.6 μg L−1. The relative standard deviation for eight replicate measurements of 100 μg L−1 Cd2+ was 0.8%. To show the validity and application of the suggested procedure, it was applied successfully for the determination of cadmium ions in various real water samples.