Preparation Of Novel Pore Structure Material And Its Application In Analytical Chemistry

In recent years,inorganic mesoporous materials,metal-organic framework compounds（MOFs）and photosensitive molecular imprinting materials,three new types of pore structure materials in the field of analytical chemistry applications gradually rise.Among them,inorganic mesoporous materials as a new type of nano-materials,because of its higher surface area compared with the general nano-materials and good nano-limited space,is expected to be used for high activity nanoparticle mimetic enzyme construction;and metal-Organic framework compounds,due to the open-tunable pore structure and large specific surface area of zeolite-like zeolite,are gradually concerned in the field of enzyme mimics research.In addition,the photosensitive molecularly imprinted material,as a novel pore structure material,because of its light response and selectivity to substrate molecules,can be used for molecular recognition in analytical chemistry.These materials open new doors for the development of analytical chemistry applications,but their good application in analytical applications still depends on the improvement and development of the material preparation method.In view of this,the thesis can be divided into three parts:（1）Three kinds of iron and cobalt oxide mesoporous materials were synthesized by simple template-free method,and its properties and applications as a peroxide mimetic enzyme were discussed;（2）Two kinds of mesoporous iron oxide and MOF composites were prepared by simple aqueous self-assembly method.The properties of the catalysts as peroxide and their applications in analytical chemistry were discussed.（3）A novel photoresponsive molecularly imprinted hydrogel based on azobenzene derivatives was synthesized and used to identify tetracycline in milk.The thesis is divided into six chapters,the main contents are as follows:Chapter 1: The literature review is summarized from four aspects,including study on mimic enzymes of nanomaterials,the preparation of inorganic mesoporous materials and the application progress in the analysis,preparation of MOF and their application in the field of mimic enzymes research,and the preparation of photoresponsive molecularly imprinted materials and its application in the analysis,.Chapter 2:Mesoporous materials have great potential in the field of mimetic enzymes due to their high specific surface and obvious domain effect.Due to the fact that variable metals are involved,inorganic materials such as Fe₃O₄ are difficult to prepare by conventional template methods.In this chapter,by designing a new method for the preparation of mesoporous Fe₃O₄,not only the mesoporous Fe₃O₄ is prepared effectively,but also because the template is not needed,the operation is quick and easy.The result of XRD,FT-IR,TG,SEM,TEM,TEM and BET show that the four kinds of Fe₃O₄ particles prepared under controlled synthesis conditions have obvious mesoporous structure.The release of CO₂ is the dominant factor in the precipitation,and the pore structure parameters of Fe₃O₄ can be controlled by adjusting the amount of aluminum salt.The effects of four kinds of mesoporous Fe₃O₄ particles on the oxidation of 3,3 ’,5,5’-tetramethylbenzidine（TMB）by H₂O₂ were investigated.The results of influence factors research shows that the four kinds of mesoporous Fe₃O₄ have the best mimic enzyme activity at p H=3.0³.5 and 55⁶0℃.Not only showed a stable evolution of the catalytic activity related to the pore structure of the material,but also improved the temperature tolerance compared with the non-porous nano Fe₃O₄.Steady-state kinetics studies show that the affinity of four kinds of mesoporous Fe₃O₄ compared with the nano Fe₃O₄ on the substrate changes significantly,while the affinity of H₂O₂ is obviously improved,while the affinity to TMB is decreased.And this is the result of the selective effect of mesoporous materials on the macromolecule substrate.The best active mesoporous Fe₃O₄ was used to detect H₂O₂,which had a good linear response in the range of 1 25 μM,and the detection sensitivity was better than that of the general non-porous nano Fe₃O₄ reported in the literature.Chapter 3:This chapter designs a new method for preparing mesoporous Co₃O₄.Although hydrothermal synthesis and high temperature conversion are needed,it is quick and easy to operate because of the absence of template.By means of XRD,FT-IR,TG,SEM,TEM and BET results show that of prepared four kinds of Co₃O₄ particles have the obvious pore structure,and the release of CO₂ in the process of precursor pyrolysis was the dominant factor of the pore formation.Furthermore,pore structure parameters of mesoporous Co₃O₄ can be controlled by adjusting the amount of aluminum salt.Four kinds of mesoporous Co₃O₄ particles without modification were directly used for the catalytic color reaction of H₂O₂ oxidating TMB.The results of influence factors research shows that the four kinds of mesoporous Co₃O₄ have the best mimic enzyme activity at p H=3.0 and 65℃,and their tolerance to temperature has significantly improved compared with the general nano Co₃O₄.Steady-state kinetics studies show that the affinity of four kinds of mesoporous Co₃O₄ compared with the general nano Co₃O₄ on the catalytic substrate changes significantly,resulting in the catalytic enzyme activity is better than the literature.The mesoporous Co₃O₄ with the best catalytic activity was used to detect H₂O₂,which had a good linear response in the range of 1²5 μM,and the detection sensitivity was better than that of the conventional nano Co₃O₄ reported in the literature.Chapter 4: In this chapter,a novel hydrothermal method for the preparation of mesoporous CoFe₂O₄ has been developed.Since the template is not required,the operation is quick and easy.By means of XRD,FT-IR,TG,SEM,TEM and BET analysis show that of prepared four kinds of CoFe₂O₄ nanoparticles have obvious pore structure,and the release of CO₂ in process of precipitation is the dominant factor of pore formation.Furthermore,through regulating the amount of aluminum salt can control mesoporous CoFe₂O₄ pore structure parameters.Then,the four kinds of mesoporous CoFe₂O₄ nanoparticles prepared without modification were directly used for the catalytic color reaction of H₂O₂ oxidating TMB.The results of reaction influence factors research show that the mesoporous CoFe₂O₄ prepared has the best mimic enzyme catalytic activity at p H=3.0 and 55℃,and its temperature tolerance compared with general inorganic nano oxides have increased.Steady state kinetic studies showed that the affinity of the four kinds of mesoporous CoFe₂O₄ prepared to the two substrates compared with general CoFe₂O₄ nanoparticle occurred obvious change,when the affinity to TMB decreased,obtained higher affinity to H₂O₂ at the same time.The mesoporous CoFe₂O₄ with the best activity has been used to detect hydrogen peroxide,which has a good linear response in the range of 1 25μM.Chapter 5:In this paper,two novel MOF composites ZIF-67 @ Fe2O3 and ZIF-67 @ Fe₃O₄ were prepared by the self-assembly of Fe2O3 and Fe₃O₄.The method was simple,convenient and efficient.The XRD,FT-IR,TG,SEM,HR-TEM and BET characterization showed that the composition changed the pore structure and surface chemical composition of the original materials,leading to the affinity of the catalytic substrate H₂O₂ and TMB improve.The prepared ZIF-67,Fe2O3,Fe₃O₄,ZIF-67 @ Fe2O3 and ZIF-67 @ Fe₃O₄ were used to catalyze the color reaction of H₂O₂-oxidized TMB.The composite had the best catalytic activity at p H = 3.0 and 45 ℃,its catalytic activity was significantly higher than Fe2O3,Fe₃O₄ and ZIF-67.The catalytic activity was significantly higher than that of Fe2O3,Fe₃O₄ and ZIF-67.The two composites were used for hydrogen peroxide measurement,ZIF-67 @ Fe2O3 in the range of 0.25²5 μM,ZIF-67 @ Fe₃O₄ in the range of 1⁵0 μM has a good linear response.Among them,ZIF-67 @ Fe₃O₄ has a wider range of hydrogen peroxide detection compared with the mesoporous Fe₃O₄ prepared in Chapter 3.Chapter 6: A photosensitive molecularly imprinted hydrogel（MIH）membrane with azobenzene derivatives as a monomer and tetracycline（TC）as a template was prepared.The performance studies showed that the photosensitivity of this MIH membrane was stable and had no obvious photolysis after 20 cycles.The MIH membrane has specific affinity for TC and can be used to quantify uptake and release TC at 365 and 440 nm alternately.The concentration of TC in the range of 0²00μM and the photo isomerization rate constants of azobenzene in MIH hydrogels are linear.Based on this,this chapter establishes a rapid method for the determination of trace TC in aqueous food.After a simple pretreatment,the material was used to determine trace amounts of TC in milk.