Preparation Of Magnetic Derived Polydopamine Composites And Its Application In Emerging Pollutant Analysis

In recent years,the development of highly efficient,easily renewable,and biodegradable extraction materials has become one of the important research areas in analytical science.Polydopamine?PDA?material,which derived from the unique adhesion behavior of mussel animal,is a type of biopolymer material and has the advantages of good biocompatibility,easy degradation and multi-reactive group.Moreover,PDA material can adhere to most of material surface.In the thesis,two kinds of magnetic derived polydopamine material have been developed and investigated the enrichment performance of emerging pollutants.The main research contents and results are as following three parts:1.Themagneticdodecyl-modifiedpolydopaminecomposite(Fe₃O₄@PDA-C₁₂@PDA)was prepared successfully.The structure and morphology of the prepared composite were characterized by Fourier transform infrared?FT-IR?,X-ray diffraction?XRD?,transmission electron microscope?TEM?,scanning electron microscopy?SEM?and thermogravimetric?TG?.The thickness of the coated dodecyl-modified polydopamine composite ranged from 50 to 150 nm.The composite coating was amorphous.The results showed that the proposed composite can efficiently extract estradiol,estrone,bisphenol A and tetrabromobisphenol A.The adsorption mechanism of estrogen depended mainly on the hydrophobic interaction.The enrichment efficiency of estradiol on 15 mg proposed composite can be achieved as 97%within 2 min when the sample solution was 10 mL and the concentration was1 mg/L.The adsorption kinetic and thermodynamic behavior of estradiol on the resulting composite was found to be fitted with pseudo second-order model and Freundlich model,respectively.The estradiol that loaded into the composite could be eluted completely by 2 mL acetonitrile.After 10 adsorption-desorption recycles,the adsorption rate of estradiol was still kept above 90%.The restricted access ability of the proposed composite has been investigated by using casein as the target interferent.The recoveries of estradiol in three samples including 10%glucose solution,milk and honey samples have calculated and ranged from 90 to 107%.It indicated that the prepared composite in this study had good stability,selectivity and repeatability.2.A analytical method based on Fe₃O₄@PDA-C₁₂@PDA composite as the extraction materials has been developed for the determination of three biguanides by magnetic solid phase extraction coupled with HPLC-FLD.Phenanthraquinone was chosen as the derivatizing reagents to react with metformin,buformin,and phenformin.The derivatization and extraction conditions were investigated in detail.The proposed method was validated as well.Under the optimal conditions,good linearity range of the method can be obtained as two orders of magnitude for each analyte?R>0.99?.The method showed good intra-day?n=5?and inter-day?n=3?reproducibility,with RSDs reaching 2.7⁹.2%.The detection limits of metformin,buformin,and phenformin were calculated to be 3.15,4.46 and 1.8 nmol/L.Finally,the anti-interference ability of the method was evaluated.In the presence of interfering substances,the spiked recoveries of three analytes ranged from 85.0%to112.0%,indicating that the method has good anti-interference and accuracy.3.Magnetic poly-levodopa composite?Fe₃O₄@PL-Dopa?was prepared successfully.Based on Fe₃O₄@PL-Dopa composites as the enrichment materials,an efficient and accurate analytical method was developed for the determination of three triphenylmethane bactericides in water sample by HPLC-DAD.Characterization of Fe3O4@PL-Dopa composite was carried out by various analytical techniques.The adsorption mechanism of malachite green?MG?and crystal violet?CV?depended mainly on the hydrophobic interaction and the electrostatic interaction.The extraction conditions were investigated in detail.The proposed method was validated as well.Under the optimal conditions,good linearity range of the method can be abtained as three orders of magnitude for each analyte?R=0.9999?.The method showed good intra-day?n=5?and inter-day?n=3?reproducibility,with RSDs reaching 1.5⁴.8%.The detection limits of MG and CV were 0.435?g/L and 0.464?g/L.Though MG and CV were not detected in the water sample,the spiked recoveries ranged from 77.8%to 100.0%,indicating that the method has good anti-interference and accuracy.