Antimicrobial Activity Removal Research Articles

Wüstite as a catalyst source for water remediation: Differentiated antimicrobial activity of by-products, action routes of the process, and transformation of fluoroquinolones

Wüstite under simulated solar irradiation with addition of H2O2 was used to treat enrofloxacin and levofloxacin in water. Wüstite was characterized, showing 2.1 eV of bandgap and species of Fe3+ on the surface that favor its catalytic ability. The effect of light intensity, wüstite dose, concentration of H2O2, and pH on the removal of antimicrobial activity (AA, against S. aureus and E. coli), was tested, finding as suitable conditions: [intensity]: 500 W m−2, [wüstite]: 10 mg L-1, [H2O2]: 1.0 mmol L-1, and pH 6.5. Under such conditions, up to 100% of AA elimination occurred at 180 min of treatment. The Light-Wüstite-H2O2 system involved, the action of light, O2•−, 1O2, and HO•, where wüstite acted as a semiconductor and a catalyst for heterogeneous photo-Fenton. Furthermore, this system mineralized 21% of ENR, and the wüstite catalyst promoted 100% of AA removal up to the fourth reuse cycle. Interestingly, the application of Light-Wüstite-H2O2 to an actual effluent led to complete AA removal after 180 min treatment. The process action on ENR generated six stable products, exhibiting the loss of the fluorine atom (induced by light directly) and modifications on the ethyl-piperazyl group (reactive region according to calculations of atomic charge) by radical attacks. The relationship between the AA and structural transformations showed that those products that retained quinolone and piperazyl moieties had AA.

Contrasting the performance of photo-Fenton at neutral pH in the presence of different organic iron-complexes using hydrogen peroxide or persulfate as oxidants for naproxen degradation and removal of antimicrobial activity

This is the first study to compare the combination of different iron complexes (Fe3+-oxalate (FeOx), Fe3+-citrate (FeCit), Fe3+-nitrilotriacetic acid (FeNTA), Fe3+-ethylenediaminetetraacetic acid (FeEDTA) and Fe3+-ethylenediamine-N,N′-disuccinic acid (FeEDDS) with distinct oxidants (H2O2 and S2O82−) on the degradation of naproxen (NAP) via photo-Fenton. Experiments were performed in distilled water and in sewage treatment plant effluent and different Fe/organic ligand molar ratios, oxidant concentrations and radiation sources (black light and sunlight) were tested for each complex. Photo-Fenton at neutral pH was efficient for naproxen degradation in the presence of all iron complexes. Fe/ligand molar ratio was strongly affected by the ligand type, best results were obtained in the presence of Fe/EDDS (1:1) and Fe/NTA (1:1), Fe/EDTA (1:2), Fe/Cit (1:3) and Fe/Ox (1:12). Although NAP removal in distilled water was faster in the presence of H2O2 (max 20 kJ m−2 required) when compared to S2O82− (max 90 kJ m−2 required), better performance of S2O82− was observed in sewage treatment plant effluent. Antimicrobial activity was only observed in the presence of FeEDDS, yet it was eliminated after treatment in the presence of S2O82−. A critical comparison in terms of operational and electrical energy costs indicates that using FeCit complex with H2O2 is the most cost-effective alternative in both matrices.

Degradation of the emerging concern pollutant ampicillin in aqueous media by sonochemical advanced oxidation processes - Parameters effect, removal of antimicrobial activity and pollutant treatment in hydrolyzed urine

This work presents the degradation of ampicillin (a highly consumed β-lactam antibiotic) in aqueous media by sonochemical advanced oxidation processes. Initially, effects of frequency, power and operation mode (continuous vs. pulsed) on the antibiotic degradation by sonochemistry were analyzed. Then, under the suitable operational conditions, pollutant degradation and antimicrobial activity (AA) evolution were monitored. Afterwards, computational calculations were done to establish the possible attacks by the hydroxyl radical to the ampicillin structure. Additionally, the antibiotic degradation in synthetic hydrolyzed urine by ultrasound was performed. Finally, the combination of sonochemistry with Fenton (sono-Fenton) and photo-Fenton (sono-photo-Fenton) was evaluated. Our research showed that ampicillin removal was favored at low frequency, high power (i.e., 375 kHz, 24.4 W) and continuous mode (exhibiting an initial degradation rate of 0.78 μM min−1). Interestingly, ampicillin degradation in the hydrolyzed urine by sonochemistry alone was favored by matrix components (i.e., the pollutant showed a degradation rate in urine higher than in distilled water). The sonochemical process decreased the antimicrobial activity from the treated water (100% removal after 75 min of treatment), which was related to attacks of hydroxyl radical on active nucleus (the computational analysis showed high electron density on sulfur, oxygen and carbon atoms belonging to the penicillin core). Sono-photo-Fenton system achieved the fastest degradation and highest mineralization of the pollutant (40% of organic carbon removal at 180 min of treatment). All these aspects reveal the good possibility of sonochemical advanced oxidation technologies application for the treatment of antibiotics even in complex aqueous matrices such as hydrolyzed urine.

Elimination of Isoxazolyl-Penicillins antibiotics in waters by the ligninolytic native Colombian strain Leptosphaerulina sp. considerations on biodegradation process and antimicrobial activity removal

In this work, Leptosphaerulina sp. (a Colombian native fungus) significantly removed three Isoxazolyl-Penicillin antibiotics (IP): oxacillin (OXA, 16000 μg L−1), cloxacillin (CLX, 17500 μg L−1) and dicloxacillin (DCX, 19000 μg L−1) from water. The biological treatment was performed at pH 5.6, 28 °C, and 160 rpm for 15 days. The biotransformation process and lack of toxicity of the final solutions (antibacterial activity (AA) and cytotoxicity) were tested. The role of enzymes in IP removal was analysed through in vitro studies with enzymatic extracts (crude and pre-purified) from Leptosphaerulina sp., commercial enzymes and enzymatic inhibitors. Furthermore, the applicability of mycoremediation process to a complex matrix (simulated hospital wastewater) was evaluated. IP were considerably abated by the fungus, OXA was the fastest degraded (day 6), followed by CLX (day 7) and DCX (day 8). Antibiotics biodegradation was associated to laccase and versatile peroxidase action. Assays using commercial enzymes (i.e. laccase from Trametes versicolor and horseradish peroxidase) and inhibitors (EDTA, NaCl, sodium acetate, manganese (II) ions) confirmed the significant role of enzymatic transformation. Whereas, biomass sorption was not an important process in the antibiotics elimination. Evaluation of AA against Staphylococcus aureus ATCC 6538 revealed that Leptosphaerulina sp. also eliminated the AA. In addition, the cytotoxicity assay (MTT) on the HepG2 cell line demonstrated that the IP final solutions were non-toxic. Finally, Leptosphaerulina sp. eliminated OXA and its AA from synthetic hospital wastewater at 6 days. All these results evidenced the potential of Leptosphaerulina sp. mycoremediation as a novel environmentally friendly process for the removal of IP from aqueous systems.

Abatement and toxicity reduction of antimicrobials by UV/H2O2 process

Antimicrobials are continuously detected in environmental waters and their removal is important to avoid health and microorganisms damage. In this work, the peroxidation assisted by ultraviolet radiation (UV/H2O2) was studied to verify if the process was able to degrade sulfaquinoxaline and ofloxacin antimicrobials and to remove the toxicity and the antimicrobial activity of the solution. This process was effective on degradation of the antimicrobials, despite the antimicrobial activity removal, the toxicity of the solution increased throughout the reaction time.

Evaluation of water matrix effects, experimental parameters, and the degradation pathway during the TiO2 photocatalytical treatment of the antibiotic dicloxacillin

The photocalytic degradation of dicloxacillin (DXC) using TiO2 was studied in synthetic and natural waters. The degradation route and the effect of different experimental variables such as pH, applied power, and the initial concentrations of DXC and the catalyst were investigated. The best performances were achieved at a natural pH 5.8 and using 2.0 g L−1 of TiO2 with 150 W of applied power. The photodegradation process followed Langmuir-Hinshelwood kinetics. The water matrix effect was evaluated in terms of degradation efficiency in the presence of organic compounds (oxalic acid, glucose), Fe2+ ion and natural water. An increase in degradation was observed when ferrous ion was part of the solution, but the process was inhibited with all evaluated organic compounds. Similarly, inhibition was observed when natural water was used instead of distilled water. The extent of degradation of the process was evaluated following the evolution of chemical oxygen demand (COD), antimicrobial activity (AA), total organic carbon (TOC) and biochemical oxygen demand (BOD5). Total removal of DXC was achieved after 120 min of treatment and 95% mineralization was observed after 480 min of treatment. Additionally, the total removal of antimicrobial activity and a high level of biodegradability were observed after the photocalytical system had been operating for 240 min.