Preparation of self-assembled polyaniline nanotubes for removal of nickel (II)

Abstract

Polyaniline (PANI) nanotubes were prepared by the self-assembly method in the presence of various organic acid dopants for removal of Ni(II). The small organic acid dopants were leading to phenazine templating mechanism of self-assembled PANI nanotubes while the long hydrophobic were leading to micelles as soft template mechanism. All the nanostructures formed by doping PANI with different acids were nanotubes but nanorods and nanoparticles also co-exist. The outer diameters of obtained PANI nanotubes were in range of 220-330. The inner diameter of PANI nanotubes doped with DBSA was larger than those of PANI doped with other small organic acids. However, the nanorods were obtained much more than nanotubes when PANI nanotubes doped with DBSA. PANI nanotubes doped with carboxylic acid dopants were more uniform than those doped with sulfonic acid dopants. Moreover, alkyl and benzyl moieties contained in dopants insignificantly affected the morphology of PANI nanotubes. When the carboxylic acid dopants contain hydroxyl group, the PANI nanotubes aggregated to formed dendrites. For the additional of methanol in reaction solution, the nanotubes and nanorods became irregular and lost their uniform morphology. The uniformity of nanotubes was excellent as the molar ratio is 0.2. PANI nanotubes can be used for removal of Ni(II) ions in solution. The adsorption capacity of PANI nanotubes that doped with various dopants was similar. The suitable condition that result the maximum adsorption amount was pH 6 and contact time of 18 h.