Zn2+ PVC-based membrane sensor based on 3-[(2-furylmethylene) amino]-2-thioxo-1,3-thiazolidin-4-one

Abstract

The 3-[(2-furylmethylene)amino]-2-thioxo-l,3-thiazolidin-4-one (FIT) was used as an excellent ionophore in construction of a Zn2+ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 3% FTT and 5% sodium tetraphenyl borate (TBP). This membrane sensor shows very good selectivity and sensitivity towards Zn2+ over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The membrane sensor revealed a great enhancement in selectivity coefficients for Zn2+ ions, in comparison to the previously reported Zn2+ membrane sensors. Theoretical studies also showed the selective interaction of TFF and Zn 2+ ions. The proposed membrane sensor exhibits a Nernstian behavior (with slope of 29.3 ± 0.3 mV per decade) over a wide concentration range (1.0 × 106-1.0 × 10-2) with a detection limit of 8.5 × 10-7 M (52 ng mL-1). It shows relatively fast response time, in the whole concentration range (< 20 s), and can be used for at least 10 weeks in a pH range of 3.0-7.0. The proposed membrane sensor was successfully used in direct determination of Zn2+ ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.