Ultra-trace determination of Cr (VI) ions in real water samples after electromembrane extraction through novel nanostructured polyaniline reinforced hollow fibers followed by electrothermal atomic absorption spectrometry

In this study, a combination of nanostructured polyaniline reinforced electromembrane extraction (EME) and electrothermal atomic absorption spectrometry (ETAAS) was employed for the separation and extraction of ultra-trace levels of Cr(VI) from real water samples. In this regard, polyaniline (PANI) decorated hollow fibers were made via electrochemical polymerization of aniline in an acidified medium. The extraction performance and selectivity of Cr(VI) via the anion exchange process were improved because of the existence of nanostructured PANI in the hollow fiber pores. The effective surface area of PANI nanostructure increased the separation performance by enhancing the possible interactions of PANI with Cr(VI) via anion exchange mechanism. The influential factors on extraction such as pH, extraction solvent, agitation speed, extraction time, and applied potential were systematically evaluated. In optimized conditions, a good linearity between 0.02 and 2 ng mL(-1) (R-2 value = 0.9972), superb enrichment factor (106), and good repeatability (RSD%, n = 4, 8.9%) for 1.0 ng mL(-1) of Cr(VI) solution were achieved. In addition, the extraction recovery was equal to 70.6% in this condition and the detection limit (S/N ratio of 3:1) and limit of quantification (S/N ratio of 10:1) were 0.006 and 0.02 ng mL(-1), respectively. Finally, the recommended method was employed with success to determine trace amounts of Cr(VI) ions in real water samples.