Efficient removal of heavy metal ions using hydrophilic thiacalix[4]arene doped polyaniline: Conductivity, isotherm and kinetic study

The adsorption capacity of polyaniline doped by thiacalix[4]arene tetrasulfonate (PANI-TCAS) towards Cu(II), Cd(II), Co(II) and Cr(III) was investigated through batch adsorption techniques. Experimental data were fitted to Langmuir, Freundlich, Redlich-Peterson and Temkin equation models and the sorption capacity was calculated. The kinetic study was carried out through Pseudo-first-order, pseudo-second-order, Elovich kinetic and Intraparticle diffusion models. The pseudo-second-order rate equation was better described by the adsorption process. XRD spectra and SEM and TEM images of the adsorbent revealed a homogeneous distribution of nanosized particle structure with porous surface. This morphology brings about high adsorption capacity for the PANI-TCAS molecular nanocomposite which was confirmed by AFM micrograph. The conductivity of thiacalix[4]arene tetrasulfonate doped polyaniline after metal ion adsorption revealed increment with a 100 order of magnitude enhancement