Adsorption of lead ions from aqueous solutions using magnetite nanoparticles: factorial optimization and isotherm analysis

Introduction The presence of lead ions in water bodies represents a persistent environmental problem due to their toxicity, mobility, and bioaccumulation capacity, which demands the development of efficient and sustainable treatment alternatives. In this context, the present study aimed to evaluate the adsorption of lead ions in aqueous solutions using magnetite nanoparticles through factorial optimization of operating conditions and isotherm analysis. Methods was developed under a quantitative experimental approach, employing a full factorial 2 3 design that considered solution pH, contact time, and adsorbent dosage as independent variables. The experiments were conducted in batch systems, and the obtained data were analyzed using descriptive and inferential statistics, including analysis of variance and regression models, supported by the SPSS and Orange software. Likewise, Langmuir and Freundlich isotherms were fitted to describe the adsorption equilibrium. Results showed that magnetite dosage is the factor with the greatest influence on removal efficiency, followed by pH and contact time, achieving high adsorption percentages under moderately alkaline conditions, short contact times, and higher amounts of adsorbent. The satisfactory fit to both isotherm models indicated the coexistence of monolayer mechanisms and surface heterogeneity. Conclusion magnetite nanoparticles exhibit outstanding adsorptive performance for Pb(II) removal in aqueous solutions, demonstrating high efficiencies under controlled operational conditions. The results confirm that the process is strongly dependent on adsorbent dosage and system pH, while contact time contributes to the stabilization of adsorption equilibrium.