Study On Preparation Of Novel Porous Materials And Their Extraction And Adsorption Performance For Organic Pollutants

The safety of food and the environment is an important issue related to the national economy and people’s livelihood.However,a wide range of trace pollutants exist widely in food and the environment,posing serious threats and hidden dangers to people’s daily lives.It is urgent to develop efficient adsorbent materials and advanced sample pretreatment technologies to remove and detect various pollutants.In this paper,several representative pollutants,such as polycyclic aromatic hydrocarbons,tetracycline antibiotics,aflatoxin B₁ and its precursors,were selected to evaluate the adsorption and extraction performance of porous materials.These works provided a strong technical support for the detection,removal and risk control of trace pollutants in food and environment.The main research findings are as follows:（1）Hollow porous carbon microsphere（HPCS）derived from Ni MOFs were prepared by high-temperature calcination using Ni based metal organic frameworks（Ni-MOFs）as templates.The prepared HPCS had a remarkable hollow porous structure and a high specific surface area.The unique structure of this material could provide an efficient molecular diffusion path and abundant adsorption active sites for solute adsorption.HPCS was coated on the surface of stainless steel wire using a physical coating method to prepare solid-phase microextraction fibers.Combined with gas chromatography-flame ionization detector,the fibers showed excellent extraction performance for six trace polycyclic aromatic hydrocarbons（PAHs）in water.The developed analytical method had a wide linear range(0.001～100 ng m L^-1),an ultra-low detection limit(0.0003～0.01 ng m L^-l)and good precision.The relative standard deviation of single fiber was 0.5%～5.3%（n=3）,the relative standard deviation between fibers was 3.1%～9.1%（n=3）,and the service life was long（>200 times）.The spiked recovery six polycyclic aromatic hydrocarbons was 73.2%～120.8%,and the relative standard deviation was0.5%～5.3%.In conclusion,a simple,efficient and sensitive method has established for the detection of polycyclic aromatic hydrocarbons in water samples,providing a solid foundation for water quality analysis.（2）Using ferrocene as a magnetic and carbon source,Si O₂ as a hard template,Si O₂@Fe₃O₄@C material was prepared by a simple hydrothermal synthesis method,and then magnetic porous carbon material with hollow gradient structure（HG-Fe₃O₄@C）were prepared through high-temperature calcination of Si O₂@Fe₃O₄@C and alkaline washing,which was used as a magnetic adsorbent to extract and enrich aflatoxin B₁（AFB₁）and the precursor substance Averantin（AVN）and Sterigmatoxin（ST）.Combined with HPLC,an analytical method was firstly established for accurate and sensitive detection of AFB₁,AVN,and ST.The proposed analytical method has good linear relationship with R² ranging from0.9959 to 0.9997.The detection and quantification limits of the three analytes are 0.03～0.47μg L^-1 and 0.10～1.41μg L^-1,respectively.The method was applied to the determination of AFB₁,AVN,and ST in three rice samples,with spiked recoveries in the range of 74.03%to119.11%and relative standard deviations ranging from 0.21%to 8.04%.The developed new method in this work was successfully used to detect AFB₁ and its precursor substances in food,providing a solid technical support for early warning of AFB₁.（3）Using ZIF-67 as a precursor,yolk-shell-ZIF-67（YS-ZIF-67）was prepared by controlled etching with tannic acid,and used for efficient adsorption of tetracycline hydrochloride antibiotics.YS-ZIF-67 not only retained the original skeleton structure and functional groups of ZIF-67,but also formed a yolk shell structure with a layered porous surface.YS-ZIF-67 exhibited good adsorption performance for chlortetracycline hydrochloride,tetracycline hydrochloride,and doxycycline hydrochloride.YS-ZIF-67provided a maximum adsorption capacity of 183.09 mg g^-1 for chlortetracycline hydrochloride,which is higher than most reported MOFs derived material adsorbents.Thermodynamic and kinetic studies were conducted using tetracycline hydrochloride as a template molecule,and the results showed that the adsorption process of YS-ZIF-67 was in line with the Langmuir adsorption isotherm model.The YS-ZIF-67 derived from ZIF-67 was used to absorb tetracycline antibiotics for the first time,providing a new way to expand the application of MOFs derived materials in antibiotics.