Potentiometric Determination of Heavy Metals Concentrations in Trace by Using Calixarene as Electroactive Materials

Functionalized calixarene molecules 5,11,17,23-tetra-tert-butyl-25,26,27-tris (chlorocarbonylmethoxy)-28-hydroxycalix [4] arene for Cd (II) and 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis (chlorocarbonylmethoxy) calix [4] arene for Ni (II) were tested as a possible ionophore in ion selective electrodes (ISEs) and successfully applied for the detection of heavy metals ions from environmental and industrial waste waters. These electrodes gave more stable potential readings when used around neutral pH 5.5-8.5 in both cases. The sensors were found to work satisfactorily in partially non-aqueous media up to 25% (v/v) content of acetone, methanol or ethanol and could be used over a period of 5 months. Potentiometric selectivity coefficients as determined by match potential method (MPM) indicate excellent selectivity for Cd²⁺ and Ni²⁺ ions. The sensors could be used successfully in the estimation of cadmium and nickel in electrochemical battery wastes and also as indicator electrodes in potentiometric titration.