Fabrication, characterization and adsorption of lead ions by doped barium hexaferrite nanoparticles

Abstract The citrate combustion technique was employed to synthesize barium hexaferrites represented by the formula BaFe 11.5 Y 0.5 O 19 , where Y denotes Zr, Zn, Ni, and Gd. XRD analysis confirms the hexagonal structure of these materials, which are classified under the space group P63/MMC-(No 194). The smallest crystallite size is observed in BaFe 11.5 Gd 0.5 O 19 , with measurements recorded at 36.968 nm according to the Halder-Wagner method. The band gap is calculated using the Tauc model. The introduction of dopant ions (Zr, Zn, Ni, and Gd) resulted in the establishment of electronic energy levels, which caused distortions in the sample and generated new locations for stabilizing charge carrier species within the samples. The BET plot shows H3 hysteresis with a type II isotherm, indicating that the inter-particle voids contribute to meso-porosity with an average pore diameter of 9.351 nm. The samples are applied in wastewater treatment, specifically serving as purifiers for lead-contaminated water. The impact of contact time is examined for all samples, revealing that BaFe 11.5 Zr 0.5 O 19 and BaFe 11.5 Gd 0.5 O 19 achieved the highest efficiencies of 99.693% and 99.237%, respectively. Moreover, BaFe 11.5 Zr 0.5 O 19 adhered to the intra-particle diffusion model, while BaFe 11.5 Zn 0.5 O 19 , BaFe 11.5 Ni 0.5 O 19 , and BaFe 11.5 Gd 0.5 O 19 correspond to the pseudo-second-order model, suggesting that the adsorption mechanism is primarily influenced by chemical processes.