Ion exchangers as adsorbents for removing metals from aquatic media

A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals.