Adsorption And Analysis Of Quinolone Antibiotics In Water

Quinolone antibiotics with broader antibacterial spectra are widely used as human and veterinary drug.However,this kind of antibiotics cannot be completely metabolized after ingestion by organisms.Quinolone antibiotics have been detected frequently in pharmaceutical industry wastewater,medical wastewater,livestock wastewater,aquaculture wastewater,effluent of domestic sewage treatment plant as well as surface water.For these antibiotics-containing wastewaters,one important issue is the development of a suitable method to remove quinolone antibiotics in wastewater and another is the development of analytical method to detect trace quinolone antibiotics in water.Recently,adsorption technology with high efficiency and simple operation has received growing concern.What's more,this technology can serve as a pre-treatment of oxidation and mineralization treatment.For environmental consideration,adsorbents derived from raw materials with high efficiency,low cost and good environmental compatibility is worthy to be explored.Here,the adsorbents perform two functions:removing pollutants in water and extracting trace pollutants for detection and analysis.In this thesis,we used natural Calotropis gigantea fiber and silicate minerals to remove quinolone antibiotics from water,and explored the adsorption-desorption behavior of quinolone antibiotics on these materials.In addition,we used the natural fiber as the solid phase extraction material to enrich trace quinolone antibiotics in aqueous matrixes to expand the fiber's application in sample pre-treatment.The content of this thesis is mainly divided into four parts.?1?NaClO₂ as the oxidant was used to chemically modify Calotropis gigantea fiber?CGF?to improve its surface hydrophilicity.Subsequently,a thorough investigation was performed on the factors that influence the adsorption capacity of resulting NaClO₂-CGF,including pH,contact time,initial concentration of antibiotics,and so on.According to the experimental results,a monotonic increase in the adsorption capacity was observed with increasing the initial pH from 2.0 to 6.0,beyond which a sudden decrease occurred.The adsorption kinetics indicated that the adsorption process could reach equilibrium within 30 min.The adsorption isotherms suggested that the whole adsorption process followed the Langmuir isotherm,with the saturated adsorption capacity was calculated to be 50-70 mg/g for enrofloxacin?Enr?,ciprofloxacin?Cip?and norfloxacin?Nor?.Further,NaClO₂-CGF was stable and reusable as it still had considerable adsorption capacity after five adsorption-desorption cycles.Finally,the dynamic adsorption performance was investigated in a fixed bed column filled by NaClO₂-CGF,and the experimental data could be described by the Thomas model.?2?Using NaClO₂-CGF as the bio-template,a facile chemical oxidation method was applied to modify the surface of NaClO₂-CGF,with pyrrole as the modified monomer and FeCl₃ as the initiator.According to?Box-Behnken Design-Response Surface Method?BBD-RSM results,the optimal preparation conditions were as follows:acetonitrile,80%?v:v?;pyrrole,0.2 mL;reaction time,30 min.Subsequently,a detail investigation was performed on the factors that influence the adsorption capacity of PPy-O-CGF,including pH,contact time initial concentration of antibiotics,and so on.According to the experimental results,a monotonic increase in adsorption capacity was observed with increasing the initial pH from 2.0 to 8.0,beyond which the adsorption capacity decreased.The adsorption kinetics indicated that within 30 min,the adsorption capacity could reach above 75%of the saturated adsorption capacity.From the Langmuir isotherm,the saturated adsorption capacity was calculated to be 80-90 mg/g for Enr,Cip and Nor.Using a solution with high ionic strength as the desorption solution,the adsorption capacity of PPy-O-CGF showed a decreasing tendency with increasing the adsorption-desorption cycles.Nevertheless,an appreciable adsorption capacity was still be observed,suggesting its good reusability.?3?Using three silicate minerals as the adsorbents,i.e.tourmaline,halloysite and biotite,the removal of quinolone antibiotics in water was studied.The physicochemical properties for the three silicate minerals were firstly characterized in detail.According to the characterization results,the main components were SiO₂ and Al₂O₃ for the three minerals.However,the specific surface area?47.01 m²/g?and pore volume(18.32×10^-2 cm³/g)of halloysite were higher than the other two minerals.Subsequently,a detail investigation was performed on the factors that influence the adsorption capacity of three minerals,including pH,contact time and initial concentration of antibiotics,and so on.The experimental results showed that the adsorption capacity of three silicate minerals was higher at pH=6.0.The adsorption kinetics indicated that the adsorption process could reach equilibrium within 60 min.The adsorption process of tourmaline and halloysite was more consistent with Langmuir isotherm,while biotite fitted well with Freundlich isotherm.From Langmuir isotherm,the saturated adsorption capacity of halloysite was calculated to be 21.7 mg/g.All the three silicate minerals could be regenerated by 0.1 mol/L NaOH.After four adsorption-desorption cycles,halloysite still had good adsorption capacity.?4?NaClO₂-CGF was used as the solid phase extraction material to enrich the trace quinolone antibiotics in water.Subsequently,high performance liquid chromatography tandem ultraviolet detector was performed to determine the sample concentration.The influence of mobile phase on the separation efficiency was studied in detail.According to the results,the optimal separation conditions were 20%methanol?v:v?as the organic phase,0.2%phosphate?v:v?and pH=3.0 in aqueous phase.In addition,a detailed investigation was performed on the factors that influence the extraction efficiency for quinolone antibiotics,including pH and flow rate of the sample solution,type,acidity and volume of an eluent.The results showed that NaClO₂-CGF-SPE presented the best efficiency when the sample pH was 4.0,and meanwhile,the efficiency did not significantly decrease when the loading flow rate was not higher than 8 mL/min.What's more,6 mL methanol containing 10%acetic acid could effectively elute the quinolone antibiotics adsorbed on NaClO₂-CGF-SPE.Under the optimized conditions,good liner relationship?>0.99?,limits of detections?LODs?from 0.20-0.48?g/L,and liner range from 2-20?g/L were obtained.