The Detection Technology,migration Rule And Removal Mechanism Of Quinolone Antibiotics In Reclaimed Water

Antibiotics,with the high curative efficiency,broad antibacterial spectrum and strong bactericidal effect,have been widely used in prevention and treatment of infectious diseases.Since excessive abuse and improper treatment of antibiotics,it leads to environmental pollution,and harm to ecosystem.It is also likely to cause antibiotic residues in food with ecological cycle,and harm human health indirectly.At the same time,antibiotics may give rise to risks,such as allergy,resistance and resistance.Therefore,the antibiotics residual in environment and food cannot be ignored.Taking antibiotics as subject,this paper mainly carried out researches as follows.(1)In order to make effective use of recycled water,this study investigated the types of antibiotics in certain recycled water.A mass spectrometry library with 52 compounds including quinolones,sulfonamides,and cephalosporin was developed using ultra high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry(UHPLC-Q-TOF-MS).The water samples were enriched by HLB solid phase extraction column,separated by C18 column and detected by Q-TOF mass spectrometry detector.The antibiotics in the water samples were screened using established library.The results showed that antibiotics could be detected in the reclaimed water samples,while quinolones showed the highest positive results.(2)A novel method based on dispersive solid-phase extraction(dSPE)coupled with through ultrahigh performance liquid chromatography tandem mass spectrometer(UHPLC-MS/MS)was developed for determination of sixteen trace quinolone antibiotics(QNs)in reclaimed water samples.Metal-organic frameworks UiO-66 were prepared by solvent thermal method and used as duped adsorbents.After the quinolones in the samples were enriched by UiO-66 under acidic conditions,they were separated by BEH C18 column,eluted with the mixture solution of methanol and aqueous solution included 0.1%formic acid,detected by UHPLC-MS/MS,and quantified by external standard method.The mass spectrometer was operated in the multi-reaction-monitoring(MRM)mode with a positive electrospray ionization(ESI+)source.The results showed that 16 QNs can be well adsorbed by UiO-66 with enrichment factor of dSPE ranged from 38 to 98.After regeneration,UiO-66 showed good performance at least for 5 times.Binding molecular diameter,the possible adsorption mechanism was investigated.The probably main interaction of nalidixic acid,oxolinic acid,flumequin and cinoxacin with adsorbents is through pore structure,and for other QNs is surface adsorption mainly based on Lewis acid-base interaction and π-π stacking(aromatic-aromatic interactions).The developed method is easy operation,high enrichment factor,high sensitivity and short analysis time.Thus,the method is of great potentiality for rapid detection of trace sixteen QNs contained in reclaimed water samples.(3)The lettuce and three kinds of sprouts were cultivated with reclaimed water included ofloxacin and norfloxacin.At the same time,no antibiotics added in reclaimed water samples were also used for blank control.Take a sample in three parallel every three days by quarter sampling method,and then changed the water every two days.Through taking vegetable cultivation time as abscissa and the content of antibiotics in vegetables as ordinate,the migration rule was studied.The results showed that the migration of ofloxacin and norfloxacin happened in lettuce and three sprouts,and the migration amount of the drug tends to increase with the growth of cultivation time.The migration amount of ofloxacin is obviously greater than that of norfloxacin.The phenomenon is confirmed by density functional theory(DFT)calculation and molecular dynamics(MD)optimization.Ofloxacin can be detected in the sprouts after 20 days cultivation with the initial concentration of 100 ng·L-1 in water sample.This indicates that when the concentration of ofloxacin in water samples is greater than or equal to 100 ng·L-1.There exists uncertain risk for sprout vegetables which cultivated by reclaimed water.(4)The high-throughput production of the eco-friendly MIL-88A(Fe)was achieved under mild reaction conditions with normal pressure and temperature.The as-prepared MIL-88A(Fe)was used for photo-Fenton oxidation ofloxacin in water samples.At neutral condition,40 mL ofloxacin solution with the initial concentration of 20 mg·L-1 can be completely removed in 50 minutes when MIL-88A amount and H2O2 dosage were 0.25 g·L-1 and 1.0 mL·L-1,respectively.The as-prepared MIL-88A(Fe)exhibited efficient photo-Fenton catalytic degradation of ofloxacin upon irradiation with visible light,it demonstrated good stability and reusability after three cycles.Through radical scavenger experiment,it showed that hydroxyl radicals(·OH)are the dominant reactive species and play an important role during photo-Fenton oxidation process.The OFL degradation pathway was proposed with the aid of both UHPLC-Q-TOF-MS and density functional theory(DFT)calculations.Certain atom sites in ofloxacin molecule are easily attacked by·OH with a high f+and f-value.Nine different intermediate products were identified and their corresponding toxicologic activities were assessed.Although certain products are more toxic than ofloxacin itself,the identified toxic products(TPs)were completely removed by the end of 50 min.In addition,Box-Behnken experimental methodology was implemented to evaluate the influence of co-existing anions and dissolved organic matter(DOM)on OFL elimination in real water samples.The results illustrate that the presence of SO42-has little impact on the photocatalytic efficiency.NO3-displays obvious photocatalytic inhibition,while Cl-and DOM give rise to photocatalytic enhancement at a lower concentration.