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Degradation of highly consumed fluoroquinolones, penicillins and cephalosporins in distilled water and simulated hospital wastewater by UV254 and UV254/persulfate processes

Water Research, 1 October 2017, Vol.122, pp.128-138 [Peer Reviewed Journal]

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  • Title:
    Degradation of highly consumed fluoroquinolones, penicillins and cephalosporins in distilled water and simulated hospital wastewater by UV254 and UV254/persulfate processes
  • Author: Serna-Galvis, Efraím A. ; Ferraro, Franklin ; Silva-Agredo, Javier ; Torres-Palma, Ricardo A.
  • Found In: Water Research, 1 October 2017, Vol.122, pp.128-138 [Peer Reviewed Journal]
  • Subjects: Structural Effects ; Antibiotics Removal ; Degradation Routes ; Transformation Analyses ; Antimicrobial Activity Removal ; Photochemical Treatment
  • Language: English
  • Description: In this work, three penicillins (ampicillin “AMP”, oxacillin “OXA” and cloxacillin “CLO”), two cephalosporins (cephalexin “CPX” and cephadroxyl “CPD”) and three fluoroquinolones (levofloxacin “LEV”, norfloxacin “NOR” and ciprofloxacin “CIP”) were initially treated by UV254 and persulfate activated by UV254 (UV/PS). Significant differences in degradation kinetics under UV254 irradiation were found. Photodegradation followed the order: OXA > CPX > CPD > CLO > CIP > NOR > AMP ≫ LEV. Then, in order to study the participation of direct photolysis and reactive oxygen species (ROS) in photodegradation a model antibiotic of each class (OXA, CPX and CIP) was considered. OXA and CPX were mainly degraded by direct photolysis, whereas the CIP removal involved ROS and photolysis. On the other hand, the persulfate addition (UV/PS process) improved the removals due to sulfate radical formation, especially, in the case of antibiotics with lower photodegradation levels (i.e. LEV, AMP and NOR). Computational calculations on the representative antibiotics were applied to determine the regions susceptible to electrophilic attacks by degrading agents. The functional groups of OXA and CPX followed the reactivity order: thioether ≫ β-lactam ring > benzene ring. For CIP, the piperazyl moiety presented higher reactivity than the quinolone ring. Also, the antimicrobial activity (AA) evolution during the treatments was tested. In the cases of CPX and CIP, both UV254 and UV/PS removed the AA; which were associated with structural changes in their reactive moieties: β-lactam ring and piperazyl ring, respectively. However, in the case of OXA only the UV/PS system decreased AA, which was attributed to transformations in its penicillin electron-rich nucleus (thioether + β-lactam). Finally, the applicability of UV254 and UV/PS was assessed using synthetic hospital wastewater (HWW). The processes comparison showed that for practical purposes, OXA and CIP in HWW should be treated by UV/PS, while CPX in HWW could be treated by both UV254 and UV/PS. Image 1 •Photodegradation by UV254 strongly depended on chemical structure of antibiotics.•Persulfate enhanced antibiotic eliminations, mainly those with lower photodegradations.•Thioether, β-lactam and piperazyl were the most reactive moieties to ROS and SO4-.•Active nuclei transformations led to antibiotic activity removal during treatments.•UV/persulfate was faster than UV for antibiotics removal from hospital wastewater.
  • Identifier: ISSN: 0043-1354 ; DOI: 10.1016/j.watres.2017.05.065

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