Ion-Exchange Behavior of New and Novel Zirconium(IV)-Based Composite Cation-Exchangers

ABSTRACT

The synthesized polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate composite ion exchangers were characterized by Fourier transform infrared spectroscopy, UV spectra, X-ray diffraction, scanning electron microscope, thermogravimetric analysis, and conductivity studies. The ion-exchange capacities, effect of eluent concentration, elution time, elution behavior, and pH on ion-exchange capacity were also studied to exploit the ion-exchange capability of the composites. The study revealed that polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate ion exchangers are having excellent ion-exchange capacity values for K⁺ ion 1.36 and 1.44 meq g⁻¹, respectively. The organic polymeric part of the composites provides mechanical and chemical stability, whereas the inorganic part supports the ion-exchange behavior and thermal stability. The increase in electrical conductivity is due to the inorganic and organic parts. A mechanism for the formation of the polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate composite ion exchangers is discussed, which may also be applied for the preparation of other composite ion exchangers. Sorption behavior of metal ions on the composites was studied in different solvent systems. On the basis of distribution coefficient values (K_d), it has been found that the cation-exchange materials are highly selective for Pb(II)-ions. Such modified composite materials can be applied as an electrochemically switchable ion exchanger for water treatment, especially water softening.

GRAPHICAL ABSTRACT

KEYWORDS:

• Cation exchanger
• conducting composites
• polymer matrix composites
• sol-gel method
• Zr(IV) selenoiodate
• Zr(IV) selenomolybdate

Acknowledgments

The authors are grateful to Physics Department of Aditanar College of Arts and Science,Tiruchendur, and ICP section of CECRI, Karaikudi for allowing the use of conductivity studies and XRD measurements. We would also like to acknowledge STIC, Cochin University and Madurai Kamaraj University, Madurai for providing SEM and FTIR spectral facilities.