Degradation Products Of Ciprofloxacin Research Articles

Antibiotic ciprofloxacin removal from aqueous solutions by electrochemically activated persulfate process: Optimization, degradation pathways, and toxicology assessment

Ciprofloxacin (CIP) is a commonly used antibiotic in the fluoroquinolone group and is widely used in medical and veterinary medicine disciplines to treat bacterial infections. When CIP is discharged into the sewage system, it cannot be removed by a conventional wastewater treatment plant because of its recalcitrant characteristics. In this study, boron-doped diamond anode and persulfate were used to degrade CIP in an aquatic solution by creating an electrochemically activated persulfate (EAP) process. Iron was added to the system as a coactivator and the process was called EAP+Fe. The effects of independent variables, including pH, Fe2+, persulfate concentration, and electrolysis time on the system were optimized using the response surface methodology. The results showed that the EAP+Fe process removed 94% of CIP under the following optimum conditions: A pH of 3, persulfate/Fe2+ concentration of 0.4 mmol/L, initial CIP concentration 30 mg/L, and electrolysis time of 12.64 min. CIP removal efficiency was increased from 65.10% to 94.35% by adding Fe2+ as a transition metal. CIP degradation products, 7 pathways, and 78 intermediates of CIP were studied, and three of those intermediates (m/z 298, 498, and 505) were reported. The toxicological analysis based on toxicity estimation software results indicated that some degradation products of CIP were toxic to targeted animals, including fathead minnow, Daphnia magna, Tetrahymena pyriformis, and rats. The optimum operation costs were similar in EAP and EAP+Fe processes, approximately 0.54 €/m3.

Effects of operating conditions on iron (hydr)oxides evolution and ciprofloxacin degradation in potassium ferrate-ozone stepwise oxidation system

In this study, a stepwise oxidation system of potassium ferrate (K2FeO4) combined with ozone (O3) was used to degrade ciprofloxacin (CIP). The effects of pH and pre-oxidation time of K2FeO4 on the evolution of K2FeO4 reduction products (iron (hydr)oxides) and CIP degradation were investigated. It was found that in addition to its own oxidation capacity, K2FeO4 can also influence the treatment effect of CIP by changing the catalyst content. The presence of iron (hydr)oxides effectively enhanced the mineralization rate of CIP by catalyzing ozonation. The pH value can influence the content and types of the components with catalytic ozonation effect in iron (hydr)oxides. The K2FeO4 pre-oxidation stage can produce more iron (hydr)oxides with catalytic components for subsequent ozonation, but the evolution of iron (hydr)oxides components was influenced by O3 treatment. It can also avoid the waste of oxidation capacity owing to the oxidation of iron (hydr)oxides by O3 and free radicals. The intermediate degradation products were identified by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Besides, the degradation pathways were proposed. Among the degradation products of CIP, the product with broken quinolone ring structure only appeared in the stepwise oxidation system.

α-(Fe, Cu)OOH/RGO nanocomposites for heterogeneous photo-Fenton-like degradation of ciprofloxacin under visible light irradiation.

Ciprofloxacin (CIP) is a third-generation fluoroquinolones (FQs) antibiotic, and the occurrence of CIP in the water environment has raised growing concerns owning to its environmental toxicity. In this paper, a novel α-(Fe, Cu)OOH/RGO nanocomposite was synthesized via a one-step reflux method for CIP degradation through a photo-Fenton-like process. When the RGO content was 1 wt%, CIP degradation ratio by the α-(Fe, Cu)OOH/RGO nanocomposite reached 100% under visible light irradiation within 120 min, and total organic carbon (TOC) removal ratio reached 60% within 180 min. The result of molecular fluorescence spectra highlighted that the loading of RGO on the α-(Fe, Cu)OOH significantly increased the content of hydroxyl radicals (·OH) in the heterogeneous photo-Fenton-like system and simultaneously inhibited the recombination of photogenerated electron and hole, which played critical roles in the enhancement of CIP degradation. In addition, 11 main intermediates were identified as the degradation products of CIP in the α-(Fe, Cu)OOH/RGO/H2O2/visible light reaction systems using liquid chromatograph-mass spectrometer (LC-MS) analyses. The results demonstrated that three degradation pathways for CIP removal by α-(Fe, Cu)OOH/RGO nanocomposite occurred, including (i) oxidation on the piperazine ring and dealkylation, (ii) defluorination and decarboxylation, and (iii) hydroxylation on the quinolone ring. This work would provide a novel insight of CIP degradation pathways in photo-Fenton-like processes.

Multivariate optimization of ciprofloxacin removal by polyvinylpyrrolidone stabilized NZVI/Cu bimetallic particles

A combined system of polyvinylpyrrolidone (PVP) and nanoscale zerovalent iron (NZVI) with copper (Cu) bimetallic particles (PVP-NZVI/Cu) was designed for ciprofloxacin (CIP) reduction under weak magnetic field (WMF) condition. The surface morphology and physicochemical properties of the novel catalytic materials were further characterized. In addition, the catalytic reactivity of PVP-NZVI/Cu was determined in the presence or absence of WMF. Experimental results demonstrated that the catalytic performance of PVP-NZVI/Cu system was enhanced by the introduction of WMF with maximum removal rate of CIP reaching 95.6% (120 min). Kinetic analysis exhibited that the degradation of CIP in compliance with pseudo-first-order kinetics. Eventually, the degradation products of CIP after reacting with the PVP-NZVI/Cu nanocomposites were determined by the mass spectrometry (MS). Quantitative analysis of PVP-NZVI/Cu adsorption and Fenton oxidation during the CIP removal process were also evaluated. The roles of PVP-NZVI/Cu adsorption/Fenton oxidation were dynamically changed and the Fenton oxidation was observed to be greatly strengthened as the removal process proceeded. The study provided a new insight into the removal of CIP by NZVI, which has prospect for the practical application of NZVI.

Degradation of ciprofloxacin by manganese(III) intermediate: Insight into the potential application of permanganate/bisulfite process

Permanganate could be activated by bisulfite to generate soluble Mn(III) which can oxidize organic contaminants rapidly. However, a lot of concerns need to be addressed for the application of permanganate/bisulfite (PM/BS) process. Taking ciprofloxacin as a target contaminant, the influence of pH, temperature and co-existing solutes on the degradation of organic contaminant in PM/BS process was systematically investigated. The PM/BS process oxidized ciprofloxacin with kobs 2.18–6.27 orders of magnitude larger than other oxidation processes under various reaction conditions and thus stood out. Ciprofloxacin present in real waters can be degraded effectively in the PM/BS process and the co-existing solutes have less inhibiting effect at lower pH and lower ciprofloxacin concentration. Bromate less than 5 µg/L was generated in PM/BS process even in the presence of 1000 µg/L bromide and thus bromate generation in PM/BS process was not a concern. The residual manganese species could be easily removed by aeration from real waters. The degradation products of ciprofloxacin in PM/BS process were identified and the plausible reaction pathways were proposed. Although the quinolone core structure in degradation products remained unattacked, bacterial growth inhibition bioassays and genotoxic experiments showed that the PM/BS treated ciprofloxacin samples displayed negligible cytotoxic and genotoxic potency.

Micellar oxidative transformation of ciprofloxacin: a kinetic investigation

Environmental contextPollution of the aquatic environment by drugs results not only during their manufacture, but also from the excretion of drug residues and the discharge of expired drugs by households and hospitals. The transformation of ciprofloxacin, one of the leading antibiotic drugs, in the presence of surfactants has been investigated. The results provide a better understanding of how ciprofloxacin degrades in aquatic environments by considering the effect of omnipresent surfactants. AbstractThe kinetics of the oxidative transformation, i.e. oxidative degradation, of ciprofloxacin (CIP) by chloramine-T (CAT) in cationic and anionic micelle media during the water chlorination process was studied spectrophotometrically at 275nm and 298K. The influence of added salts (1–10×10–4moldm–3) and solvent polarity of the medium on the reaction was studied. The orders with respect to substrate CIP and oxidant CAT were found to be first order in each. The variation of acid concentrations showed opposite effects in cationic and anionic micellar aggregates. Liquid chromatography–electrospray ionisation mass spectrometry was used to identify degradation products of CIP, which confirmed the full dealkylation of the piperazine ring in CIP as the major product. The piperazine moiety of CIP is the principal active site for the CAT during oxidation. Activation parameters for the CIP degradation in cationic and anionic micelles were evaluated by studying the reaction at different temperatures, which lent further support to the proposed degradation mechanism for CIP. The rate constants were evaluated to confirm the micellar effect from incorporating sodium dodecyl sulfate and cetyltrimethylammonium bromide in the reaction mixture and the intrinsic reactivity constants were determined in the aqueous as well as in the micellar pseudo-phases as 4.85 and 0.0083.

Sulfate radical-based oxidation of fluoroquinolone antibiotics: Kinetics, mechanisms and effects of natural water matrices

Widespread occurrence of fluoroquinolone antibiotics (FQs) in surface water, groundwater, soil and sediment has been reported and their remediation is essentially needed. Sulfate radical (SO4−) based advanced oxidation processes (SR-AOPs) are promising technologies for soil and groundwater remediation. In this study, the degradation kinetics, mechanisms, and effects of natural water matrices on heat-activated persulfate (PS) oxidation of FQs were systematically investigated. Experimental results clearly demonstrated that 92% of CIP was removed within 180 min (pH = 7, 60 °C). Higher temperature and lower pH facilitated the degradation of ciprofloxacin (CIP). The piperazine moiety of CIP was identified as the reactive site for SO4− attack by comparison with substructural analogs, flumequine (FLU) and 1-(2-fluorophenyl) piperazine (FPP). A comparison of the degradation of CIP, norfloxacin (NOR), enrofloxacin (ENR) and ofloxacin (OFL) confirmed that the presence of cyclopropane ring also influence the degradation of FQs. Water matrix significantly influenced the degradation of CIP and ENR, and the degradation rate followed the order of Milli-Q water (pH = 7) > groundwater > artificial seawater > artificial surface water > lake water. Degradation products of CIP in different water matrix were enriched by solid phase extraction (SPE) and then analyzed by liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (LC-ESI-MS/MS). Detailed transformation pathways of CIP were proposed and were compared with respect to different water matrices. Four transformation pathways including stepwise piperazine ring oxidation, OH/F substitution, hydroxylation, and cyclopropane ring cleavage were proposed for CIP degradation. Results clearly show that the water matrix influenced the degradation of FQs appreciably, a phenomenon that should be taken into consideration when applying SR-AOPs for remediation of soil and groundwater contaminated by FQs.

Fast photocatalytic degradation of pharmaceutical micropollutants and ecotoxicological effects

Aqueous solutions of ciprofloxacin (CP) and ibuprofen (IBP) in the presence of LaFeO3 photocatalyst, of H2O2, and of both LaFeO3 and H2O2 were irradiated under visible light. The degradation rate in the presence of both LaFeO3 and H2O2 after 5 h irradiation was more than 90% for CP and 40% for IBP, much higher than that with only H2O2 under visible light. For the sake of comparison, the experiments were also carried out in the dark, and both CP and IBP were not significantly converted. The degradation rate was enhanced by the simultaneous presence of small concentration of LaFeO3 (130mgL-1) and H2O2 (0.003M). However, tests on the aquatic acute toxicity indicate that the degradation products of CP and IBP induce toxic effects on aquatic organisms, consequently indicating incomplete detoxification after 5 h irradiation. The main degradation product of IBP was 4-isobutylacetophenone (4-IBAP), detected in the irradiated solutions by using UV/vis spectrophotometry. 4-IBAP was more toxic and showed a slower photocatalytic degradation than the parent compound. On the contrary, the toxicity of CP degradation products, although not negligible, was comparable to that of CP itself.

Decomposition reaction of the veterinary antibiotic ciprofloxacin using electron ionizing energy

The application of electron ionizing energy for degrading veterinary antibiotic ciprofloxacin (CFX) in aqueous solution was elucidated. The degradation efficiency of CFX after irradiation with electron ionizing energy was 38% at 1kGy, 80% at 5kGy, and 97% at 10kGy. Total organic carbon of CFX in aqueous solution after irradiation with electron ionizing energy decreased 2% at 1kGy, 18% at 5kGy, and 53% at 10kGy. The CFX degradation products after irradiation with electron ionizing energy were CFX1 ([M+H] m/z 330), CFX2 ([M+H] m/z 314), and CFX3 ([M+H] m/z 263). CFX1 had an F atom substituted with OH and CFX2 was expected to originate from CFX via loss of F or H2O. CFX3 was expected to originate from CFX via loss of the piperazynilic ring. Among the several radicals, hydrate electron (eaq-) is expected to play an important role in degradation of veterinary antibiotic during irradiation with electron ionizing energy. The toxicity of the degraded products formed during irradiation with electron ionizing energy was evaluated using microbes such as Escherichia coli, Pseudomonas putida, and Bacillus subtilis, and the results revealed that the toxicity decreased with irradiation. These results demonstrate that irradiation technology using electron ionizing energy is an effective was to remove veterinary antibiotics from an aquatic ecosystem.

High-Performance Thin-Layer Chromatography with Densitometry for the Determination of Ciprofloxacin and Impurities in Drugs

A thin-layer chromatographic (TLC)-densitometric method has been developed for identification and quantification of ciprofloxacin (Rf = 0.61) and an ethylenediamine compound (Rf = 0.42), a desfluoro compound (Rf = 0.48), by-compound A (Rf = 0.53), and fluoroquinolonic acid (Rf = 0.68) as ciprofloxacin degradation products in pharmaceutical preparations. By using chloroform-methanol-25% ammonia (43 + 43 + 14, v/v/v) as the mobile phase and silica gel 60 F254 high-performance TLC plates as the stationary phase, it was possible to separate individual constituents that, when subjected to ultraviolet (UV) densitometric analysis at 330 nm for fluoroquinolonic acid and 277 nm for the other compounds, gave well developed peaks allowing easy qualitative and quantitative analyses. DMSO-methanol (1 + 1) was used to extract drug constituents. The method showed high sensitivity (limit of detection 10 to 44 ng), a wide linearity range (3 to 20 microg/mL), and good precision (2.32 to 6.46% relative standard deviation) and accuracy (percentage recoveries 98.62 to 101.52%) for individual constituents.

Study of the evolution and degradation products of ciprofloxacin and oxolinic acid in river water samples by HPLC-UV/MS/MS-MS

The results of a degradation study of the (fluoro)quinolone antibiotics ciprofloxacin and oxolinic acid in river water samples are presented in this paper. The decomposition of these compounds at ambient temperature was monitored during five months by HPLC-UV, and two consecutive degradation processes (photo- and bio/chemical-degradation) were observed in both cases although with different degradation rates. Ciprofloxacin was completely degraded after 3 months whereas 80% of oxolinic acid remained unaltered after five months of storage. The analysis of the degradation compounds formed was carried out using MS and tandem MS-MS, allowing the identification of four new ciprofloxacin transformation products not previously described in the literature. Possible degradation pathways for this antibiotic in river water are proposed.