Antibiotic removal from water: Elimination of amoxicillin and ampicillin by microscale and nanoscale iron particles

Zerovalent iron powder (ZVI or Fe⁰) and nanoparticulate ZVI (nZVI or nFe⁰) are proposed as cost-effective materials for the removal of aqueous antibiotics. Results showed complete removal of Amoxicillin (AMX) and Ampicillin (AMP) upon contact with Fe⁰ and nFe⁰. Antibiotics removal was attributed to three different mechanisms: (i) a rapid rupture of the β-lactam ring (reduction), (ii) an adsorption of AMX and AMP onto iron corrosion products and (iii) sequestration of AMX and AMP in the matrix of precipitating iron hydroxides (co-precipitation with iron corrosion products). Kinetic studies demonstrated that AMP and AMX (20 mg L⁻¹) undergo first-order decay with half-lives of about 60.3 ± 3.1 and 43.5 ± 2.1 min respectively after contact with ZVI under oxic conditions. In contrast, reactions under anoxic conditions demonstrated better degradation with t_1/2 of about 11.5 ± 0.6 and 11.2 ± 0.6 min for AMP and AMX respectively. NaCl additions accelerated Fe⁰ consumption, shortening the service life of Fe⁰ treatment systems.