Exceptional ion-exchange selectivity for perchlorate based on polyaniline films

Polyaniline (PANI) films were electrochemically synthesized on graphite electrode and their ion-exchange selectivities for ClO₄⁻ were investigated. Cyclic voltammetry (CV) results showed that PANI-H₂SO₄ film represented higher selectivity for ClO₄⁻ than PANI–HCl and PANI–HClO₄. Furthermore, the CV records of PANI–H₂SO₄ film in different acidic solutions demonstrated that ClO₄⁻ exchange was performed in a lower potential range (from −0.025 V to 0.097 V), which is distinguished from SO₄²⁻ and Cl⁻. Additionally, chronoamperomertry (CA) studies of PANI–H₂SO₄ film in 0.1 M various acidic solutions (H₂SO₄, HCl and HClO₄) confirmed that the diffusion coefficient values in HClO₄ (13.319/18.184 × 10⁻⁶ cm² s⁻¹) were the biggest during doping/de-doping process. The exceptional ion-exchange selectivity for ClO₄⁻ was explained by the process of dominant accumulation, quick insertion of anions, and the sluggish mobility of ClO₄⁻ inside the membrane. Results of present work demonstrated that PANI may serve as a promising membrane for ClO₄⁻ removal by ion-exchange process.