Impact of Ferric Hydroxide Concentration on the Synthesis and Nitrate Removal Efficiency of gamma-Fe2O3Nanoparticles
J. Environ. Nanotechnol., Volume 15, No 1 (March 2026) pp. 658-667
Abstract
γ-Fe₂O₃ (maghemite or gamma iron oxide) nanoparticles were synthesized via an alcoholic sol–gel route using varying Fe(OH)3 precursor concentrations (0.05–0.20 M) to systematically investigate the influence on nanoparticle yield, structural properties, and nitrate adsorption performance. Increasing the precursor concentration from 0.05 M to 0.15 M enhanced product yield while maintaining high surface area and optimal particle size. However, further increase to 0.20 M resulted in larger crystallite size and reduced surface area. Structural and morphological characteristics were confirmed by XRD, FTIR, BET, TGA/DSC, and FESEM analyses. Batch adsorption experiments at neutral pH demonstrated a maximum nitrate removal capacity of approximately 25 mg/g for nanoparticles synthesized at 0.15 M Fe(OH)3. Adsorption kinetics followed the pseudo-second-order model, while equilibrium data were best described by the Langmuir isotherm, indicating monolayer adsorption behavior. The presence of competing anions slightly reduced nitrate removal efficiency, with sulfate exerting the most significant influence. The study establishes an optimal precursor concentration for high-yield synthesis of γ-Fe₂O₃ nanoparticles with enhanced nitrate adsorption capability, addressing the limited understanding of precursor concentration effects in alcoholic sol–gel systems.
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