Cd (II) Ion-Selective Electrode Based on 2 –Acetylthiophene Semicarbazone in Polymeric Membrane

Abstract

A new polyvinylchloride membrane sensor for Cd+2 ions has been prepared using 2–acetylthiophene Semicarbazone ligand as an electroactive ionophore and dibutylphthalate (DBP) as a plasticizing agent. The best performance was recorded with a membrane composition of PVC: DBP: Ionophore: NaTPB as 31: 64: 3.2: 1.8 (w/w %).The sensor exhibits a Nernstian response for Cd+2 ions over a wide concentration range (1.0 ×10–5 to 1.0 ×10–1 M) with a slope of 29.4 ± 0.2 mV decade–1. It has a fast response time of ˂ 10 s and can be used for at least 5 weeks without any divergence in potential. The electrode can be used in the pH range from 3.4 to 7.6. The proposed sensorrevealed relatively good selectivity and high sensitivity for Cd+2 ions in presence of a number of mono, di andtrivalent interfering cations within the working range of the electrode. The electrode was successfully applied for the direct determination of Cd+2in solution and, as an indicator electrode, in potentiometric titration of cadmium ions using ethylenediamine tetraacetic acid (EDTA) as titrant. Keywords: Ion Selective Electrodes, Cadmium, PVC membrane, semicarbazide