Preparation, characterization and ion-exchange properties of a new 'organic-inorganic' composite cation exchanger polyaniline silicotitanate: Its applications for treatment of hazardous metal ions from waste solutions

Polyaniline silicotitanate an ‘organic–inorganic’ composite material, was prepared via sol–gel mixing of organic polymer polyaniline into the matrices of the inorganic precipitate of silicotitanate. The physico-chemical properties of this hybrid material were determined using atomic absorption spectrophotometry (AAS), CHN elemental analysis, ICPS, X-ray (XRD and XRF), IR, TGA-DTA and scanning electron microscopy (SEM). The data obtained proposed that the chemical formula of polyaniline silicotitanate may be written as: [Ti4O9H7Si + (– C6H5NH–)] 4H2O. Ion-exchange capacity (IEC), thermal stability and distribution behavior, etc.were also carried out to understand the cation-exchange behavior of the material. On the basis of distribution studies, the material was found to be highly selective for Cs+ and the selectivity sequence for sorption of Co2+, Cu+2, Cd2+, Cs+ and Pb2+ ions on polyaniline silicotitanate was found to be; Cs+> Pb2+> Co2+> Cu2+ > Cd+2. Thermodynamic parameters (i.e. AGo, ASo and AHo) have also been calculated for the adsorption of Co2+, Cu+2, Cd2+, Cs+ and Pb2+ ions on polyaniline silicotitanate showing that the overall adsorption process is spontaneous and endothermic.