Structural and physical investigations of Sr_1–xDy_xFe_12–yCo_yO₁₉; (x = 0, 0.05 and y = 0, 0.5) for wastewater treatment

M-type hexagonal ferrites were produced using the citrate auto-combustion technique. To understand the effects of substituting divalent Co²⁺ and rare earth elements Dy³⁺ on the structure, magnetic and removal efficiency of hexagonal ferrites, a series of samples including SrFe₁₂O₁₉, SrFe_11.5Co_0.5O₁₉, Sr_0.95Dy_0.05Fe₁₂O₁₉, Sr_0.95Dy_0.05Fe_11.5Co_0.5O₁₉ were analyzed. XRD analysis showed that all samples crystallized into a single M-type hexagonal phase. The small wavenumber absorption bands between 400 and 1000 cm⁻¹ in FTIR curves are the primary features of M-type hexagonal ferrites. Magnetic properties varied with the addition or removal of Dy³⁺ and Co²⁺ doping due to the impact of spin canting with Dy³⁺ and Co²⁺ ions on strontium and iron ions. The study aimed to gather information about doping magnetic hexaferrites, which could be a pioneering development in wastewater treatment. The study examined the impact of substitution with rare earth and divalent elements in wastewater treatment, along with potential future developments in this field. The study examined various factors affecting the adsorption of lead ions from aqueous solutions, such as pH and contact time. The maximum removal efficiency of Sr_0.95Dy_0.05Fe_11.5Co_0.5O₁₉ was approximately 99.6% at pH 7 and 25 °C after 60 min. The isotherm data fit into the Frendlish isotherm approach. The pseudo-first-order, pseudo-second-order, and intraparticle diffusion models clarified the adsorption kinetics. The capacity for adsorption of the studied samples was consistent and demonstrated through 4 cycles.