Impact of aniline-to-pyrrole ratio on the adsorption performance of polyaniline/polypyrrole aerogels towards anionic dyes

Abstract Macroporous composite aerogels, combining polyaniline (PANI) and polypyrrole (PPy), were synthesized by oxidative cryopolymerization of various ratios of the corresponding comonomers in the presence of poly(vinyl alcohol) (PVAl) stabilizer. The estimate of the conducting polymer and PVAl phase contents in the composite aerogels, made by XPS, allowed correlation of the mechanical properties of the materials with their composition. Tensile measurements showed that tensile modulus and tensile stress at break were mostly determined by the presence of PPy units, while the change in tensile strain at break correlated with the change in the PVAl content. The material, synthesized at 90 mol% of aniline in the comonomer mixture, which contained the highest fraction of the conducting polymer phase, was found to have the best adsorption performance towards the anionic dye, Reactive Black 5. Notably, it had higher fraction of the removed dye, compared to the corresponding homopolymer aerogels. Adsorption isotherm data, fitted by the Langmuir model, showed it having maximum adsorption capacity of 389.1 mg g –1 . In addition, the possibility of the adsorbent reusability for at least 5 cycles has been additionally confirmed, which makes the prepared PPy/PANI-PVAl a promising adsorbent for the application in water purification.