Amoxicillin degradation at ppb levels by Fenton's oxidation using design of experiments
ABSTRACT A central composite factorial design methodology was employed to optimise the amoxicillin degradation using the Fenton's oxidation treatment. In this study, the variables considered for the process optimisation were the hydrogen peroxide and ferrous ion initial concentrations and the temperature, for an antibiotic concentration of 450μg L(-1) at pH=3.5. This methodology also allowed assessing and identifying the effects of the different factors studied and their interactions in the process response. An appropriate quadratic model was developed in order to plot the response surface and contour curves, which was used to perform the process optimisation. From this study, it was concluded that ferrous ion concentration and temperature were the variables that most influenced the response. Under the optimal conditions (hydrogen peroxide concentration=3.50-4.28mg L(-1), ferrous ion concentration=254-350μg L(-1) and temperature=20-30°C), it was possible to achieve total amoxicillin degradation after 30min of reaction.
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ABSTRACT: In recent years, antibiotics have been considered as serious contaminants due to their high consumption and persistence in the aquatic environment. Currently, amoxicillin is one of the most widely used antibiotics and its emission into the environment encounters numerous health and environmental hazards. The main objectives of this research were focused on assessing the feasibility of using Fenton reagent in removing amoxicillin and determining the optimal conditions using Taguchi method. In addition, its effect on the rate of mineralization, biodegradation, and the removal efficiency of COD were studied. The Taguchi method was used to optimize variables and their levels using Qualitek-4 (w32b) software. The optimum values of the response variables were predicted using signal-to-noise ratio (S/N). The influence of different parameters including the initial concentration of amoxicillin, H2O2 concentration, Fe(II) concentration, pH, and reaction time at four different levels on the removal of amoxicillin in the aqueous phase were investigated. The removal efficiencies at initial concentrations of amoxicillin 10, 100, 200, and 500 mg/L were 68.64, 95.385, 98, and 99.3%, respectively. Process optimization by Taguchi method suggests that the optimal conditions for the removal of amoxicillin in the aqueous phase are as follows: the initial amoxicillin concentration of 500 mg/L, Fe(II) concentration of 5.0 mg/L, H2O2 concentration of 500 mg/L, pH 3, and the reaction time of 15 min; and level of significance for the study parameters were 60.228, 26.369, 5.638, 4.373, and 3.392, respectively. The maximum removal efficiency of COD and mineralization rate were 71.3 and 36.3%, respectively. The biodegradation rate was also increased from 0 to 0.738. In conclusion, our study demonstrated that Fenton process may enhance the rate of amoxicillin degradation in polluted water and could be used as a pretreatment step for the biological removal. The results also indicate that the Taguchi experimental design can simply predict the optimal conditions for the removal of amoxicillin in the aqueous phase using Fenton process.Desalination and water treatment 03/2015; DOI:10.1080/19443994.2015.1005143 · 0.99 Impact Factor
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ABSTRACT: The contamination of the aquatic environment by non-metabolized and metabolized antibiotic residues has brought the necessity of alternative treatment steps to current water decontamination technologies. This work assessed the feasibility of using a multistage treatment system for amoxicillin (AMX) spiked solutions combining: i) a biological treatment process using an enriched culture to metabolize AMX, with ii) a solar photocatalytic system to achieve the removal of the metabolized transformation products (TPs) identified via LC-MS, recalcitrant to further biological degradation. Firstly, a mixed culture (MC) was obtained through the enrichment of an activated sludge sample collected in an urban wastewater treatment plant (WWTP). Secondly, different aqueous matrices spiked with AMX were treated with the MC and the metabolic transformation products were identified. Thirdly, the efficiency of two solar assisted photocatalytic processes (TiO2/UV or Fe(3+)/Oxalate/H2O2/UV-Vis) was assessed in the degradation of the obtained TPs using a lab-scale prototype photoreactor equipped with a compound parabolic collector (CPC). Highest AMX specific biodegradation rates were obtained in buffer and urban wastewater (WW) media (0.10 ± 0.01 and 0.13 ± 0.07 gAMX gbiomass(-1) h(-1), respectively). The resulting TPs, which no longer presented antibacterial activity, were identified as amoxicilloic acid (m/z = 384). The performance of the Fe(3+)/Oxalate/H2O2/UV-Vis system in the removal of the TPs from WW medium was superior to the TiO2/UV process (TPs no longer detected after 40 min (QUV = 2.6 kJ L(-1)), against incomplete TPs removal after 240 min (QUV = 14.9 kJ L(-1)), respectively).Water Research 08/2014; 65C:307-320. DOI:10.1016/j.watres.2014.07.037 · 5.32 Impact Factor
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ABSTRACT: The degradation of the β-lactam antibiotic amoxicillin (AM) treated with direct UV-C and UV/H(2)O(2) photolytic processes was investigated in the present study. In addition, the antibacterial activity of the solution treated by UV/H(2)O(2) advanced oxidation was compared with AM solution treated with ozone. The degradation rate of amoxicillin in both processes fitted pseudo first-order kinetics, and the rates increased up to six fold with increasing H(2)O(2) addition at 10mM H(2)O(2) compared to direct photolysis. However, low mineralization was achieved in both processes, showing a maximum of 50% TOC removal with UV/H(2)O(2) after a reaction time of 80min (UV dose: 3.8×10(-3)EinsteinL(-1)) with the addition of 10mM H(2)O(2). The transformation products formed during the degradation of amoxicillin in the UV and UV/H(2)O(2) processes were identified by LC-IT-TOF analysis. In addition, microbial growth inhibition bioassays were performed to determine any residual antibacterial activity from potential photoproducts remaining in the treated solutions. An increase of the antibacterial activity in the UV/H(2)O(2) treated samples was observed compared to the untreated sample in a time-based comparison. However, the UV/H(2)O(2) process effectively eliminated any antibacterial activity from AM and its intermediate photoproducts at 20min of contact time with a 10mM H(2)O(2) dose after the complete elimination of AM, even though the UV/H(2)O(2) advanced oxidation process led to bioactive photoproducts.Science of The Total Environment 03/2012; 420:160-7. DOI:10.1016/j.scitotenv.2011.12.011 · 3.16 Impact Factor