Zn PVC-based Membrane Sensor Based on 3-[(2-Furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one

The 3-[(2-furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one (FTT) was used as an excellent ionophore in construction of a Zn 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 Zn 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 Zn ions, in comparison to the previously reported Zn membrane sensors. Theoretical studies also showed the selective interaction of TFF and Zn 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 × 10−6-1.0 × 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 Zn ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.