Exceptional ion-exchange selectivity for perchlorate based on polyaniline films

• The preparation of PANI films and their selectivities for ClO 4 − exchange. • PANI–H 2SO 4 showed exceptional ion-exchange selectivity for ClO 4 −. • The mechanism of ion-exchange process at PANI-H 2SO 4/ClO 4 − interface was expounded. • PANI could effectively extract and release ClO 4 − in a low potential range. Polyaniline (PANI) films were electrochemically synthesized on graphite electrode and their ion-exchange selectivities for ClO 4 − were investigated. Cyclic voltammetry (CV) results showed that PANI-H 2SO 4 film represented higher selectivity for ClO 4 − than PANI–HCl and PANI–HClO 4. Furthermore, the CV records of PANI–H 2SO 4 film in different acidic solutions demonstrated that ClO 4 − exchange was performed in a lower potential range (from −0.025 V to 0.097 V), which is distinguished from SO 4 2− and Cl −. Additionally, chronoamperomertry (CA) studies of PANI–H 2SO 4 film in 0.1 M various acidic solutions (H 2SO 4, HCl and HClO 4) confirmed that the diffusion coefficient values in HClO 4 (13.319/18.184 × 10 −6 cm 2 s −1) were the biggest during doping/de-doping process. The exceptional ion-exchange selectivity for ClO 4 − was explained by the process of dominant accumulation, quick insertion of anions, and the sluggish mobility of ClO 4 − inside the membrane. Results of present work demonstrated that PANI may serve as a promising membrane for ClO 4 − removal by ion-exchange process.