Efficient hexavalent chromium removal through recyclable flower-like cerium phosphate polyaniline nanocomposite via adsorption-reduction pathway

The efficient removal of Cr(VI) from water is a crucial environmental concern, and in this study, the focus was on addressing this issue by investigating a new flower-like cerium phosphate polyaniline nanocomposite (CePO₄-PANI) material. This material was synthesized using an in situ oxidative polymerization method, resulting in a flower-like morphology that was confirmed through field emission scanning electron microscopy and transmission electron microscopy images. The adsorption of Cr(VI) onto the material followed the pseudo-second-order kinetic model and the Langmuir isotherm model, with a high adsorption capacity of 129.87 ± 2.1 mg g⁻¹ at room temperature in a wide pH range of 2 to 6. The CePO₄-PANI nanocomposite is a promising adsorbent for the treatment of Cr(VI), with high tolerance to co-anions and efficient regeneration after multiple adsorption-desorption cycles. XPS spectra revealed the simultaneous adsorption of Cr(VI) and in situ chemical reduction to Cr(III) via electrostatic attractions and chelation methods. Its unique flower-like morphology, coupled with its impressive adsorption capacity, co-anion tolerance, and efficient regeneration, make it a promising alternative to existing technologies for water treatment.