Molecular dynamics study of nitrate adsorption from aqueous solutions using activated carbon modified with Fe2O3 nanoparticles: The impact of Fe2O3 nanoparticles

KS Borazjani and S Rezaee and H Sharififard and M Bonyadi, EUROPEAN PHYSICAL JOURNAL PLUS, 140, 487 (2025).

DOI: 10.1140/epjp/s13360-025-06433-7

Groundwater resources, especially in rural areas, suffer from nitrate ion (NO3-) contamination, posing significant health risks. This research examines the influence of iron(III) oxide (Fe2O3) nanoparticles on the adsorption mechanisms and kinetics of adsorbed NO3- from a 0.118 M sodium nitrate solution by activated carbon (AC) and AC/Fe2O3 nanocomposites to develop simulation guidelines that align with experimental data using molecular dynamics simulations. For AC, the results reveal that sodium ion (Na+) and NO3- were adsorbed by 8.22% and 6.85%, respectively, due to the concentration gradient between the solution and the adsorbent. This approximately balanced adsorption originates from the principle of local conservation of electrostatic charge distribution, which limit the effectiveness of NO3- removal. In AC/Fe2O3 nanocomposite, adsorption occurs due to both the concentration gradient and the Coulombic forces of the Fe2O3 nanoparticle. The nanoparticle mitigates the effects of the local electrostatic charge conservation principle, leading to a 2.5-fold increase in the adsorption of NO3- compared to Na+. A comparison of the amount of NO3- adsorbed at equilibrium reveals values of 2.7905 mg g-1 for the AC/Fe2O3 and 1.5926 mg g-1 for AC, indicating that Fe2O3 enhances the NO3- removal process. The agreement between computational and experimental data underscores the algorithm's capability to capture nanosecond-scale temporal and spatial attributes that are difficult to investigate experimentally.

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