Preparation Of Metal-Organic Frameworks And Theirapplications In Pollutant Removal And Analysis

In recent years,metal-organic framework materials as new porous materials have been developed.It has become a research hotspot of researchers at home and abroad because of its advantages of adjustable pore size,high specific surface area,stable structure and easy functional modification.In the environmental field,metal-organic framework materials,as a new type of adsorbent,are showing broad application prospects in the removal and enrichment analysis of pollutants in water.In this paper,two new metal-organic framework composites were developed for the removal and analysis of pollutants in water and milk.Triclosan and triclocarban are highly effective broad-spectrum fungicides in water.In recent years,due to the heavy use of people,as domestic sewage enters the environmental water body,it poses a threat to water safety and human health.In addition,the frequent use of sulfonylurea herbicides has also led to their continuous detection in water bodies and foods.Because of their low content in water and food,they need to be pre-treated and enriched before they can be detected.In this paper,a new metal-organic framework composite was prepared,which was applied to the removal of triclosan and triclocarban in water,and the enrichment detection of sulfonylurea herbicides in water and milk.The following work was carried out:?1?The magnetic MOF material,Fe₃O₄@SiO₂-UiO-66,was prepared by solvothermal method.The structure and morphology were characterized by X-ray diffractometer,transmission electron microscope,Fourier transform infrared spectrometer,thermogravimetric analyzer,Zeta potential meter,specific surface area measuring instrument and vibrating sample magnetometer.The adsorption factors affecting triclosan and triclocarban in Fe₃O₄@SiO₂-UiO-66 materials were optimized,including the ratio of Fe₃O₄@SiO₂ and ZrCl₄,the pH value of water sample,the amount of adsorbent,salinity and adsorption time.Under optimal adsorption conditions,the saturated adsorption capacities of Fe₃O₄@SiO₂-UiO-66 to triclosan and triclocarban in water were 476.27 and 602.40mg·g^-1,respectively.The adsorption isotherm model accords with the Langmuir isotherm model;the adsorption equilibrium time is 25min,and the kinetic model conforms to the Pseudo-second-order kinetic model;its adsorption mechanism is a combination of hydrophobic interaction,hydrogen bonding,?-?conjugation and coordination,among which?-?conjugate is the main force.This material can be effectively regenerated and recycled 11 times.Compared with the traditional adsorbent,Fe₃O₄@SiO₂-UiO-66has a fast adsorption process and a large amount of saturated adsorption,which is a promising adsorbent.?2?The mixed matrix membrane?MMM?of MOFs and polyvinylidene fluoride?PVDF?,MIL-53-PVDF MMM was prepared and characterized by X-ray diffractometer,transmission electron microscope,fourier transform infrared spectroscopy.An analytical method for the determination of seven sulfonylurea herbicides in environmental water samples and milk based on MOFs membrane extraction-high performance liquid chromatography?HPLC?was developed.The factors affecting the membrane extraction efficiency were optimized by the amount of MOFs,the extraction time,the type and volume of the eluent,the elution time,the pH of the water sample,the salinity and the volume of the water sample.The linear range of the method is 0.01-10?g·L^-1,and the method detection limit is 3.75-10.30ng·L^-1.The intra-day precision?n=6?and daytime precision?n=6?of the method were4.20-13.71%and 4.35-14.25%,respectively.The method was applied to the detection of tap water,sea water and surface water,and the recovery rate of the standard addition was 77.20-111.00%.When the method is applied to the detection of milk,the spiked recovery rate is 43.60-124.00%.The MIL-53-PVDF MMM can be effectively recycled for 25 cycles.This method is simple,fast,and sensitive,and meets analytical testing requirements.