Chronopotentiometric and electroanalytical studies of Ni(II) selective polyaniline Zr(IV) molybdophosphate ion exchange membrane electrode

Abstract

Polyaniline Zr(IV) molybdophosphate (PAZMP) was synthesized by sol–gel method and its ion exchange capacity (IEC) was determined as 2.50meqg−1. On the basis of distribution co-efficient (Kd values) the material was selective for Ni(II). The Ni(II) selective membrane was prepared (IEC 0.65meqg−1) to fabricate Ni(II) selective membrane electrode with its linear potential response in the concentration range of 1×10−7M–1×10−1M. The morphology and composition of the prepared PAZMP membrane were ascertained by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) respectively. The ion exchange mechanism through membrane was determined by chronopotentiometric studies using Nernst-Planck equation at 30°C, 45°C and 60°C. As a result physical parameters such as self-diffusion coefficient (D0), energy of activation (Ea) and entropy of activation (ΔS°) were calculated. The analytical utility of this electrode was established by employing it as an indicator electrode in potentiometric titration.