Construction Of Multifunctional MOF Platform And Its Application In Pesticide Sensing And Degradation

Agriculture is the most basic industry as the foundation of people's livelihood.In the enconomic development process,the consumption of pesticides is essential for increasing the grain production for solving food scarcity.However,irregular use of pesticides brings a certain burden to the environment.Pesticide residues have caused a lot of problems like environmental pollution,public health and safety risks,which seriously threaten the health and safety of human beings.In recent years,China has appealed to construct the environment-friendly society.In response,it is urgently needed to construct accurate analysis,repair and degradation methods against pesticide residue in the environment.Traditional analytical methods include chromatography,enzyme inhibition and immunoassay have been developed for pesticide residue analysis.Nevertheless,these methods are usually complex,expensive and demand precision instruments in the analysis of real samples,which was difficient in the practical application.As for the degradation of pesticide residues,compared to the high cost of physical method,chemical degradation method is cheap.Moreover,the chemical degradation possessed higher efficiency than that of biodegradation method.Therefore,it is particularly significant to improve rapid analysis methods with simple operation,low cost and high credibility,as well as establish cheap effective and efficient degradation methods for pesticide residue for protecting the health of human life and build an environment-friendly society.Metal-organic framework materials(MOFs),a periodic reticular nanomaterial formed by the composite of metal ions and organic ligands,have been applied in the fields of gas storage and adsorption,selective catalysis,pharmaceutical and small molecular carriers,optoelectronic materials and biochemical sensing.Along with the continuous in-depth study of MOF materials,the characteristics of multi-porosity,large specific surface area and diversity in structural properties of this kind of materials are widely ultilized.Based on the new preparation and synthesis method of MOF materials,this paper constructs a pesticide sensitive residue sensing and efficient pesticide residue degradation platform.The main research contents are as follows:1.Preparation of Zr-based porphyrin MOF(FMOF).Firstly,FMOF was synthesized by Zr as nodes and porphyrin H₂TCPP as organic ligands via hydrothermal method.The prepared FMOF was characterized by various methods such as transmission electron microscopy(TEM),dynamic light scattering(DLS),Fourier transform infrared spectroscopy(FT-IR),ultraviolet-visible spectroscopy(UV-Vis),X-ray diffraction(XRD).The results confirmed the successful systhesis of the Zr-based porphyrin MOFs(FMOF).2.Construction of a bifunctional platform as the sensor and photocatalyst for the detection and degradation of nitenpyram for(NIT)by using the prepared FMOF materials.The bifunctional MOF probe was mainly studied as a sensor for detecting trace NIT in the environment and a photocatalyst for produceing free radicals to promote pesticide degradation.The specific and sensitive detection of the pesticide NIT was achieved by fluorescence spectrometry.The detection range of NIT was 0.05?10.0 ?g mL^-1,and the detection limit was calculated to be 0.03 ?g mL^-1.This method was also applied in real samples.Finally,taking advantage of the photocatalysis ability to produce ROS,FMOF exhibited the efficient degradation against a variety of pesticides including nitenpyram,thifluzamide,isoproturon,and atrazine,in which the degradation rate of nitenpyram was over 95%.3.Cerium oxide was synthesized by a simple hydrothermal method,and CeO_x@MIL was constructed by the encapsulation of CeO_x via in-situ growth of MIL^-101-NH₂-typed MOF.Then CeO_x@MIL was characterized by TEM,FT-IR and XRD.To evaluate the pesticide degradation ability of the designed material,the oxygen production and the photocatalysis of CeO_x@MIL were tested using the oxygen indicator[Ru(dpp)₃]Cl₂ and photocatalytical experiments,respectively.Furthermore,CeO_x@MIL achieved the efficient degradation of atrazine based on its excellent oxygen self-production ability and photocatalytic performance.