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

Zerovalent iron powder (ZVI or Fe(0)) 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 Fe(0) and nFe(0). Antibiotics removal was attributed to three different mechanisms: (i) a rapid rupture of the beta-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 t1/2 of about 11.5 +/- 0.6 and 11.2 +/- 0.6 min for AMP and AMX respectively. NaCl additions accelerated Fe(0) consumption, shortening the service life of Fe(0) treatment systems. Fe(0) is efficient for the aqueous removal of the beta-lactam antibiotics and chlorides enhanced the removal rate by sustaining the process of iron corrosion.