Sepúlveda, P., Suazo-Hernández, J., Cáceres-Jensen, L., de la Luz Mora, M., Denardin, J., García-García, A., Cornejo, P. & Sarkar, B. (2025). Iron oxide nano-adsorbent doped with nickel and palladium for phosphorus removal from water. RSC advances, 15(32), 26321-26337. https://doi.org/10.1039/D5RA02256H

Abstract: Excessive phosphorus (P) in surface and ground water can cause serious environmental issues. This study aims to synthesize and characterize novel iron oxides (Fe_xO_y) nanoparticles (NPs) with and without Ni and Ni–Pd doping and unravel the NPs' performance and mechanism for P removal from water. X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy results confirmed successful doping of Ni and Ni–Pd on Fe_xO_y NPs. Fe_xO_y–Ni NPs exhibited a higher specific surface area and isoelectric point than Fe_xO_y and Fe_xO_y–Ni–Pd NPs. The kinetic data for P adsorption on Fe_xO_y NPs fitted to the pseudo-first order model and Fe_xO_y–Ni and Fe_xO_y–Ni–Pd NPs fitted to the pseudo-second order model. Adsorption isotherm data for Fe_xO_y NPs fitted to the Freundlich model and Fe_xO_y–Ni and Fe_xO_y–Ni–Pd NPs fitted to the Langmuir model. The maximum P adsorption capacity was the highest for Fe_xO_y–Ni (35.66 mg g⁻¹) followed by Fe_xO_y–Ni–Pd (30.73 mg g⁻¹) and Fe_xO_y NPs (21.97 mg g⁻¹), which was opposite to the P desorption order of these adsorbents. The adsorption and characterization analysis suggested that inner-sphere complexes and co-precipitation were the key mechanisms for P adsorption on Fe_xO_y–Ni and Fe_xO_y–Ni–Pd NPs. Therefore, Fe_xO_y–Ni NPs were a highly effective adsorbent for removing P from water.