A Novel Terpolymer Membrane-Based Electrode Sensor for Selective Determination of Cd(II) Ions

Abstract

A new polymeric membrane sensor for Cd(II) ion based on methyl acrylate-acrylonitrile-methyl methacrylate terpolymer as membrane carrier has been synthesized via atom transfer radical polymerization (ATRP) method at 60 ºC. Preliminary investigation with the membrane exhibited promising selectivity for Cd(II) ion with a slope of 32.02 mV/decade and the same could be estimated in the concentration range of 1 × 10-6 − 1 × 10-1 M in the working pH range of 4-6 for up to 90 days. The potentials generated across the membrane were reproducible and the response time was less than one minute. The electrode works well even in a partially non-aqueous media. The effect of surfactant and detergent on the working of Cd(II) selective electrode was also studied. A decrease in potential was observed in the presence of appreciable amount of surfactant and detergent. Addition of plasticisers was found to greatly improve the performance of membrane, best results being obtained with the membrane ratio (NaTPB:TP:TBP::1:100:06), exhibiting a working concentration range of 1 × 10-6 − 1 × 10-1 mol L-1 with a short response time of 10 s. The proposed sensor shows significantly good selectivity toward Cd(II) ion in comparison with some alkali, alkaline earth, transition and heavy metal ions. It was successfully employed as an indicator electrode in potentiometric titration of cadmium(II) ions against EDTA solution.