Investigation of templated and supported polyaniline adsorbent materials

Various structural forms of poly(aniline) (PANI) were synthesized in aqueous solution with different acids and/or a chitosan template support to afford nanoparticle PANI (NP; synthesized in water), bulk-PANI (aqueous acetic acid (HAc), hydrochloric acid (HCl) and sulfuric acid (SA) and a chitosan-PANI composite (CH) material. The polymer materials were characterized using spectroscopy (H-1 NMR, FTIR, UV-vis), TGA and P-XRD. The polymer materials were structurally diverse according to their unique morphology related to the ratio between quinoid and benzenoid monomer units of PANI. The sorption and kinetic uptake properties of PANI materials with methylene blue (MB) in aqueous solution were studied where variable sorption capacity was observed, as follows: NP > HAc > HCl > SA > CH. The Sips isotherm model describes the adsorptive equilibrium uptake while the pseudosecond order kinetic model describes the time dependent uptake of MB. The monolayer sorption capacities (Q(m)) reported herein are among the highest (ca. 6-fold greater) relative to other Q(m) values reported for PANI materials in the literature.