A novel ionic liquid/polyoxomolybdate based sensor for ultra-high sensitive monitoring of Al(III): Optimization by Taguchi statistical design

Abstract

A novel ionic liquid electrostatically supported Nano-Cs-polyoxomolybdate modified carbon paste electrode (Nano-IL-PMo12-CPE) has been developed by using 1-n-butyl-3-methylimidazolium tetrafluoroborate (Bmim.BF4) as a superconductive hydrophobic binder. The supramolecular gel (IL-PMo12) exhibits an ordered structure, various physicochemical properties, and specifically as a result of its substantial reversible self-assembly, it can be used as an intelligent ion-exchange smart platform in the carbon paste bulk of the electrode. The provided materials were characterized by XRD, FT-IR, UV–vis, and elemental analyses. As expected, a significant linear correspondence was found between the sensor output signal (emf/mV) and logarithm of Al(III) ion activity with a Nernstian slope of 19.9 (±0.2) mV decade−1 over a wide concentration range of 1.0 × 10−9 to 2.2 × 10−1 mol L−1 (R2 = 0.9997). The sensor considered, exploits an astounding lower limit of detection and short response time of 7.94 × 10−10 mol L−1 and 8 s respectively within the working pH range of 2.0 to 5.0. A statistical design of experimental (Taguchi method with Qualitek-4 software and L16 orthogonal array robust design) was implemented in this work to optimize the process to achieve the least number of experimental runs as much as possible. Ultimately, practical capability of the sensor was investigated successfully by assessment of Al(III) ion quantity in some aqueous samples namely mineral water, Al-Mg syrup, black tea extract, and ore samples (Basalt and Andesite), in perfect agreement with flame atomic absorption spectroscopy (FAAS).