Tailoring Bi, Sn co-doped CoZnFe2O4 for Ni (II) and Cs (I) removal: Insights into characterization, adsorption activity, kinetics, thermodynamics, and non-linear isotherms

Co 0.5-x Zn 0.5-x Bi x Sn x Fe 2 O 4 ( CZBSFs, 0.00 ≤ x ≤ 0.10) nanoparticles were synthesized via co-precipitation and characterized structurally, morphologically, and magnetically. Co-doping with Bi and Sn reduced crystallite size (14.04 to 7.29 nm), increased lattice parameter (8.384 to 8.410 Å), and enhanced superparamagnetism (91.33 % to 94.67 %). XRD, TEM, FTIR, and Raman analysis confirmed cubic spinel formation. The oxidation states of the constituent elements were confirmed by XPS spectroscopy, indicating that the octahedral positions are occupied by Bi and Sn ions. CZBSFs were studied for water remediation of Ni (II) and Cs (I) radionuclides. The q m and %R achieved by CZBSFs ( x = 0.10) were 43.2 mg/g, 86.4 %, and 42.6 mg/g, 85.3 %, after 180 min for 100 ppm Ni (II) and Cs (I), respectively. Adsorption followed the Redlich-Peterson isotherm and pseudo-second-order kinetics, with endothermic behavior. CZBSFs demonstrate effective treatment of wastewater contaminated with radioactive metals. • Bi and Sn codoped ferrite nanoparticles were synthesized via co-precipitation method. • Co-doping reduced crystallite size and enhanced superparamagnetism contribution. • The prepared nanoparticles achieved high adsorption capacities for Ni(II) (43.2 mg/g, 86.4 %) and Cs(I) (42.6 mg/g, 85.3 %).