Ion-Exchange Properties of Colloidal Particle Consisting of Polyaniline and Poly(vinyl alcohol) Fixed on Silica-gel Powder

Abstract

A colloidal powder was prepared by fixing polyaniline (PANI, conducting polymer), poly(vinyl alcohol) (PVA, surfactant stabilizer) and a suitable dopant anion to silica-gel powder. This hydrophilic composite colloidal particle incorporates anions with the protonation of PANI in an acidic solution. The anion can be exchanged with other anions when the colloid is immersed in an acidic solution. Thus, the PANI colloid works as an ion exchanger. The ion-exchange properties on the composite colloidal powder were investigated. Anions were successfully and easily exchanged in the order Br -< Cl -< NO3 -< ClO4 -< SCN -. This ion-exchange selectivity corresponds largely to the ion-exchange equilibrium constants, which are based on a hydrophobic interaction between the anion and colloid. However, this ionexchange selectivity does not agree simply with the lipophilic order, but is instead explainable by a gap in the effective ion-exchange capacity due to a size effect between the micropore on the colloidal particle formed by the dopant anion in polymerization and anion sizes in the hydrophobic environment.

Electroactive Conducting Polymers for the Protection of Metals against Corrosion: from Micro‐ to Nanostructured Films

“…These ion-exchange properties have been used for practical applications such as the recovery of Cr(VI) in aqueous solutions [81] or for ion exchange of various anions [82]. These properties are highly dependent on pH, and involve a protonic equilibrium between EB and ES forms.…”

Polyaniline inhibition of filiform corrosion on organic coated AA2024-T3

“…It is well known that PAni in both EB and ES forms act as effective anion-exchangers, although the mode of ionexchange remains highly dependent upon solution pH [30][31][32][33][34]. EB can sequester both H + and Cl − species, forming the protonated PAni-Cl emeraldine salt, while PAni-pTS undergoes simple anion exchange, shown to be most effective at low pH [30,33,34], where Cl − can undergo exchange with pTS − counterions associated with the polymer backbone.…”