Degradation of ampicillin by combined process : adsorption and Fenton reaction

Abstract

When disposed incorrectly, antibiotics can cause complex effects on environmental matrices, such as bacterial resistance. In this context, the present work investigated the degradation and mineralization of the β-lactam antibiotic ampicillin (AMP) applying a combined treatment of Fenton reaction and adsorption onto granular activated carbon (GAC). Adsorption parameters of contact time (10–210 min) and GAC dosage (5– 50 g L− 1 ) were evaluated, as well as adsorption kinetics. Both in Fenton reaction and combined process, the influence of H2O2 and Fe+2 concentrations were evaluated, using five combinations of H2O2/Fe+2 : 300/60 µM, 300/80 µM, 400/70 µM, 500/60 µM and 500/80 µM. Finally, because of the combined process, GAC regeneration was investigated in 3 cycles. Best adsorption conditions were determined as 150 minutes of contact time and GAC concentration of 20 g L−1 , reaching 57% of AMP removal and adsorbed amount of 0.58 mg g−1 . All Fenton experimental conditions led to a complete degradation of AMP within 1 min, suggesting the generation rate of hydroxyl radicals was faster in the first minutes of reaction. In the combined process, similar results for degradation were found. A higher mineralization (83%) and GAC regeneration (85%) was reached at H2O2/Fe+2 = 500/80 µM, indicating the influence of H2O2 and Fe+2 concentrations. GAC regeneration efficiency for the 3 cycles were, respectively, 84%, 71% and 49%. Thus, the results demonstrate the combined process of Fenton reaction and GAC adsorption is a feasible treatment reaching high mineralization.