Degradation mechanism of amoxicillin using clay supported nanoscale zero-valent iron

Antibiotics such as amoxicillin (AMX) have been considered emerging pollutants due to their persistence in the aquatic ecosystem even at low concentrations. Thus, it is an emerging issue to develop materials effective for removal of antibiotics pharmaceuticals from wastewaters. Bentonite supported nanoscale zero-valent iron (B-nZVI) as one of the alternatives was used to remove amoxicillin. Batch experiments revealed that the degradation of amoxicillin depended on pH value of the solution, initial concentration of B-nZVI, initial concentration of amoxicillin and reaction temperature. The removal of AMX was based on an integration of adsorption and reductive degradation, which was confirmed by either adsorption or reductive kinetics. The potential AMX degradation pathway was proposed by analysis of the degraded products using high performance liquid chromatography-mass spectrometry (HPLC-MS). The removal mechanism of amoxicillin using B-nZVI includes: (1) the adsorption of amoxicillin onto iron corrosion products; and (2) reduction of AMX by nZVI on B-nZVI. Finally, the reusability of B-nZVI for degradation of amoxicillin was tested.