Fabrication and Surface Characterization of Poly(4-aminodiphenylamine) Film Modified Electrode and its Application for Lead and Cadmium Determination

Poly(4-aminodiphenylamine), Padpa, film was synthesized electrochemically on a glassy carbon electrode by potentiodynamic repetitive cycling of 4-aminodiphenylamine (4-adpa) in 1.0 M HCl. The mechanistic steps involved the oxidation of the protonated monomer to diimine species followed by its dimerization to form the mono-charged radical intermediate, which was considered as the initiation step for the progress of polymerization. The electrochemical properties and surface morphology of the film modified electrode were characterized using electrochemical and various surface scanning techniques. The XPS data demonstrated the existence of =N- bonding responsible for polymer formation, while the AFM image revealed a uniform and symmetrical fiber structure with low energy dissipation. The modified electrode was primarily applied as an environmental sensor for the simultaneous and selective determination of Cd^2+ and Pb^2+ ions in water samples. The detection limit for Cd^2+ and Pb^2+ ions was 25 and 14 µg L^-1, respectively.