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)