Amoxicillin Adsorption from Aqueous Solution by Magnetite Iron Nanoparticles: Molecular Modelling and Simulation

Molecular modelling and simulation were used to examine the efficacy of iron nanoparticles (Fe3O4-NPs) in removing amoxicillin (AMX) from aqueous media and determine the optimal conditions. Fe3O4-NPs were initially ascertained using scanning electron microscopy, and Fourier transform infrared spectroscopy. The molecular optimisation modelling via DFT confirmed AMX molecule has chemical potential (-3.59), and electrophilicity index (2.14). The results established that a small chemical hardness = 3.0 eV and molecular energy gap of 6.01 eV, which makes it reactive. The molecule of the antibiotics could interact and be absorbed by the lactase enzyme. The parameters: pH (3-7), time (15-80 min), Fe3O4-NPs dosage (0.1-1.0 g/L), and antibiotic concentration (10-100 mg/L) were studied. The impact of optimum variables pH3, and dosage (0.5 g/L) for adsorption of AMX molecules onto coated Fe3O4-NPs translated to 98% efficiency at 60 mg/l of AMX and 60 min. The adsorption data fitted the Langmuir (R-2: 0.9245) with minimal error metrics RMSE & LE; 1.2 when compared to the Freundlich isotherm R-2 (0.88) and intraparticle diffusion model R-2 (0.58). The maximum adsorption capacity of AMX to Fe3O4-NPs corresponds to 6.47 mg/g with a corresponding adsorption constant of 2.8. Furthermore, AMX adsorption onto Fe3O4-NPs followed pseudo-second-order at R-2 (0.9999), with an adsorption constant (k = 3.6 x 10(-2)g/mg.min).