Evaluation of the electrochemical anion recognition of NO3- -imprinted poly(Azure A) in NO3-/Cl- mixed solutions by ac-electrogravimetry
Résumé
During the reversible electrochemical reactions of the intrinsically conducting polymer (ICP)
films, ions are
inserted in them to balance the inner charge site of the polymer. For this reason, doped ICP
films with anions
or cations can be good candidates for the electrochemical removal of contaminant ions from wastewater. In
this work, a polymer of a phenothiazine derivative (poly(Azure A or PAA)) was electrosynthesized by cyclic
voltammetry in aqueous solutions using nitrate ions as a structural template. After that, PAA
film was
repeatedlycycled in identical conditions in a monomer-free solution. The electrochemical anion recognition
of the nitrate-imprinted poly(Azure A) NO
3
PAA
was evaluated by the combination of electrochemical
and mass impedance spectroscopy, the so called ac-electrogravimetry method. Ac-electrogravimetry
allows the selectivity of NO
3
PAA to be quantified. NO
3
PAA exhibited a special sensitivity and
selectivity for the nitrate ions over the interfering chloride ions in mixed NO
3 and Cl containing
solutions. The Dixon plots of the kinetic constants obtained by ac-electrogravimetry were used as a
graphical method to reveal that NO
3 and Cl transfers are non-competitive at lower doped states of the
polymer but competitive at higher doped states. The reversibility of nitrate incorporation controlled by
an external potential modulation, the relative low cost and easy synthesis render the NO
3
PAA
film
suitable in practical implications such as nitrate scavenger in aqueous contaminated environments.
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