Study On Synthesis Of Magnetic Pyrrole Based Hypercrosslinked Porous Organic Polymer And Its Extraction Properties For Tetracycline In Water

Tetracycline is a kind of broad-spectrum antibiotic,which was widely used in medical and health,livestock and poultry breeding industries.Due to its stable nature and strong hydrophilicity,it is easy to accumulate in the water environment,which will eventually cause pollution and threaten human health.The efficient removal and detection technology of tetracycline in environmental water has become the basis for the analysis of its pollution sources,the investigation of its toxicity,degradation and transformation,and the management,restoration of environmental water resources.While the construction of high efficiency adsorption materials is the key to the above two technologies.As a new kind of porous material,the hyper-crosslinked porous organic polymer has the advantages of high specific surface area,outstanding adsorption property,low cost,and easy industrial production,so it is widely used in the fields of pollutant removal and sample pretreatment.The magnetic composite prepared by magnetizing HCPs not only retains the characteristics of high specific surface area of HCPs,but also can quickly separate the adsorbent from the sample solution in the applied magnetic field,which has great potential for development of adsorption materials.Based on the perspective of green chemistry,this paper fabricated two kinds of pyrrole based hyper-crosslinked porous organic polymers by Friedel-Crafts reaction using pyrrole and carbazole as monomers,dimethoxy-methane as the external crosslinker,2-dichloroethane as the solvent and anhydrous ferric chloride as the catalyst.Then,the catalyst anhydrous ferric chloride was used as the iron source to magnetize the pre-synthesized pyrrole hyper-crosslinked porous materials through solvothermal reaction and obtain two kinds of magnetic pyrrole based hyper-crosslinked microporous materials Fe₃O₄/HCPs.Finally,combined with ultraviolet spectroscopy and high performance liquid chromatography,the two materials were used as adsorbents for the removal and detection of tetracycline hydrochloride in environmental water.Specific research work is as follows:In the first part,the magnetic hyper-crosslinked porous organic polymer Fe₃O₄/py-HC-Ps was synthesized by Friedel-Crafts reaction and solvothermal reaction using pyrrole as monomer,dimethoxy-methane as the external crosslinker,anhydrous ferric chloride as catalyst and magnetized iron source.Subsequently,the structure,surface area,morphology,elementary composition and magnetic strength of the materials were characterized by infrared spectroscopy（FT-IR）,X-ray powder diffraction（XRD）,nitrogen adsorption desorption isotherm analysis（BET）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）and hysteresis loop curve（VSM）.Finally,TC was used as the target analyte and Fe₃O₄/py-HCPs was used as the adsorbent to investigate the adsorption properties of Fe₃O₄/py-HCPs for tetracycline.The amount of adsorbent,initial concentration of sample solution,p H of sample solution,temperature,salt ions and humic acid on the adsorption effect were investigated successively.The kinetic and thermodynami-c characteristics of the adsorption process and the reusability of the materials were also studied.The results showed that Fe₃O₄/py-HCPs can achieve more than 90%removal rate of tetracycline under the optimal conditions,and the adsorption capacity increases with the increase of temperature.The adsorption process accords with the quasi second-order kinetic model,intragranular diffusion model and Langmuir isothermal adsorption model,which indicate the adsorption of tetracycline by Fe₃O_4/py-HCPs is a homogeneous monolayer adsorption with chemical adsorption,surface adsorption and intramolecular diffusion processes.Besides,the removal rate of adsorbent Fe₃O_4/py-HCPs remained above 78%after5 cycles,indicating that Fe₃O₄/py-HCPs had good reusability.In the second part,the magnetic hyper-crosslinked porous organic polymer Fe₃O₄/car-HCPs was synthesized by Friedel-Crafts reaction and solvothermal reaction using carbazole as monomer,dimethoxy-methane as the external crosslinker,anhydrous ferric chloride as catalyst and magnetized iron source.Subsequently,the structure,surface area,morphology,elementary composition and magnetic strength of the materials were characterized by infrared spectroscopy（FT-IR）,X-ray powder diffraction（XRD）,nitrogen adsorption desorption isotherm analysis（BET）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）and hysteresis loop curve（VSM）.It was used as an adsorbent for simultaneous magnetic solid phase extraction（MSPE）of oxytetracycline,tetracycline and doxycycline in water,then the extraction conditions,such as the quality of adsorbent,extraction time,extraction temperature,elution time,eluent type and eluent volume were optimized.Finally,the MSPE combined with high-performance liquid chromatogra-phy with ultraviolet detection（HPLC-UV）technology,established a new method for the enrichment and detection of tetracycline in environmental water.Under the optimal conditions,the linear range of the method was 5-200μg L^-1,the correlation coefficients（R²）were 0.9985,0.9963,0.9929,and the detection limit（LOD）was 0.8μg L^-1.Finally,the method was successfully applied to the analysis and detection of trace tetracycline,oxytetracycline and doxycycline in tap water,rain water and lake water,the actual sample recoveries ranged from 75.6%to 128.5%,the relative standard deviation（RSDs）is between 1.3% and 9.4%.