Electrochemical sensors based on modified PET track-etched membranes for Pb2+, Cd2+, UO22+ ions detection

In this article, electrochemical sensors based on PET track-etched membranes grafted with poly(N-vinylformamide-co-methacrylic acid) [PET TeMs-g-p(NVFA-MAA)] were developed. The modification, structure, and physicochemical properties of the grafted PET membranes were characterized by SEM, AFM, EDX, FTIR spectroscopy and contact-angle measurements. The optimal analytical performance toward Pb 2+ and Cd 2+ was achieved using PET TeMs-g-p(NVFA-MAA) (70:30), prepared at a monomer concentration of 20%, a reaction time of 60 min and a distance of 10 cm from the UV lamp. This membrane exhibited a grafting degree of 13.2%, an acid orange (AO) adsorption capacity of 35.87 μmol/g associated with the pNVFA-containing component and a toluidine blue (TB) adsorption capacity of 13.0 μmol/g associated with the carboxyl-containing pMAA component. The highest sensitivity toward UO 2 2+ was obtained using PET TeMs-g-p(NVFA-MAA) (30:70), prepared at a monomer concentration of 10%, a reaction time of 120 min. This membrane exhibited a grafting degree of 47.8%, with AO and TB adsorption capacities of 4.17 and 39.4 μmol/g, respectively. The optimized membranes were subsequently employed in a two-electrode sensing system using square wave anodic stripping voltammetry, providing limits of detection of 0.007 mg/L for Cd 2+ , 0.009 mg/L for Pb 2+ and 0.0027 mg/L for UO 2 2+ . These findings demonstrate that variation of the graft-copolymer composition and the resulting balance of surface functionalities enables tuning of the electrochemical detection performance toward different target metal ions.