Modified Thorium Oxide Polyaniline Core-Shell Nanocomposite and Its Application for the Efficient Removal of Cr(VI)

The core-shell ThO₂-PANI nanocomposite was synthesized using polyaniline (PANI) as a favorable conducting polymer and used for the removal of Cr(VI) from water. Thorium dioxide (ThO₂) nanoparticles were embedded by PANI via an in situ polymerization process. The formation of the material was investigated by XRD, FESEM, EDX, TEM, TGA-DTA, FTIR, Raman, XPS, and N₂ sorption isotherm analysis. The FESEM and TEM analyses confirmed that PANI was successfully formed on the ThO₂ surface. The ThO₂-PANI nanocomposite could effectively adsorb Cr(VI) through electrostatic attractions, which were partially reduced to Cr(III) during the adsorption experiment, ensuring the proficient adsorption as well as better removal of Cr(VI) from water. The synthesized nanocomposite material exhibited a high uptake capacity toward Cr(VI) as compared to other reported materials. The adsorption kinetics data sufficiently defined the pseudo-second-order kinetic model. The Cr(VI) adsorption onto ThO₂-PANI was greatly dependent on the solution pH. The Langmuir isotherm model followed the adsorption process better than the Freundlich isotherm with a maximum adsorption capacity of 141 mg g^-1. Thermodynamic parameters were also computed, which indicated the spontaneous and endothermic nature of the adsorption process. The current study indicates that synthesized ThO₂-PANI may be crucial for the efficient adsorption of Cr(VI).