Research On Adsorption Properties Of Hydrothermal Carbon And Applications In Solid Phase Extraction,colorimetric Sensing And Chiral Fractionation

Hydrothermal carbon materials have received extensive attention in the fields of chemistry and biomedicine,owing to the advantages of simple synthesis process,low cost,tunable structure and surface characteristics,environmental friendliness and rich source of raw materials,etc.It is still a difficulty in studying the adsorption behavior of hydrothermal carbon materials in related fields.Therefore,orientated by the analysis and application of hydrothermal carbon materials,the effects of surface adsorption behavior of hydrothermal carbon materials in the fields of magnetic solid phase extraction,colorimetric sensing and chiral fractionation were studied in this thesis.The work in this thesis is as follows:1.To improve the adsorption efficiency of the magnetic solid phase extraction adsorbents,carbon shell coated γ-Fe2O3(γ-Fe2O3@CNM)prepared via hydrothermal caramelization reaction were used as magnetic solid phase extraction adsorbents.The surface of γ-Fe2O3@CNM material has a caramelized cross-linked polymerized carbon shell,which allows γ-Fe2O3@CNM possess porous,high specific surface area and amphiphilic properties.These properties provide abundant adsorption sites and allow efficient mass transfer during adsorption/desorption process.γ-Fe2O3@CNM adsorb malachite green and crystal violet through electrostatic interaction and π-π interaction,with the adsorption capacities of 34.2 mg/g and 27.9 mg/g,respectively.Based on γ-Fe2O3@CNM,a magnetic solid-phase extraction-ultra-high performance liquid chromatography-mass spectrometry method was developed for the enrichment and analysis of trace triphenylmethane dyes.2.In order to improve the affinity of enzyme-like material to substrate in colorimetric detection,cystine-glucose Maillard conjugates-composited Cu1.8S(Cu1.8S-cgmc)microspheres with peroxidase activity were designed and synthesized.The hydrothermal carbon material on the surface of Cu1.8S-cgmc with functional groups such as-COOH、-OH and-NH2 allows higher dispersibility in aqueous solution.The effect of different carbon content of Cu1.8S-cgmc on the peroxidase activity was studied.Cu1.8S-cgmc with a carbon ratio 1.83%has the highest catalytic activity.The adsorption equilibrium constant of Cu1.8S-cgmc on the substrate was 9.89-fold higher than that of bare Cu1.8S based on the isothermal calorimetric titration investigation.The higher affinity of Cu1.8S-cgmc to the substrate enhanced the peroxidase catalytic activity of Cu1.8S.Based on the peroxidase properties of Cu1.8S-cgmc,a colorimetric method for the determination of H2O2 and glutathione was developed.3.To improve the electron transfer at the interface between nanoenzyme and substrates in colorimetric detection,Fe2+/Fe3+ loaded hydrothermal carbon spheres(CNPs@Fe)composite was designed and synthesized for the colorimetric determination of H2O2.The catalytic efficiency of CNPs@Fe on H2O2 is 4.25 and 70.4 times higher than that of Felland Fe3O4,respectively,indicating the strongest catalytic activities of CNPs@Fe.The aromatic structure of CNPs was confirmed by high resolution mass spectrometry.The aromatic structure is not only beneficial to accelerate electron transfer,but also can adsorb the colorimetric substrate,resulting in enhanced peroxidase-like activity of CNPs@Fe.Based on the colorimetric method of CNPs@Fe,the linear range of H2O2 detection is 10-1200 nmol/L with a limit detection of 3 μmol/L.4.To explore the role of the adsorption behavior of hydrothermal carbon materials in the chiral fractionation of pollutant enantiomers,hydrothermal chiral carbon quantum dots(CQDs)and achiral CQDs were designed and synthesized.The degradations of ofloxacin enantiomers by CQDs were studied.Chiral CQDs show selective degradation over ofloxacin enantiomers,while achiral CQDs have no such effect.Using(+)-CQDs as the research model,the reason of the chiral fractionation of ofloxacin enantiomers by chiral CQDs was revealed by fluorescence quenching,thermodynamic analysis and theoretical calculations.It demonstrated that the heterochiral interaction((+)-CQDs/(-)-ofloxacin)is stronger than homochiral interaction((+)-CQDs/(+)-ofloxacin).Therefore,the chiral fractionation of enantiomeric structures produced by hydrothermal chiral carbon materials is mainly resulted from the different adsorptions between them.