Preparation And Study Of PVA/Starch Degradable Membrane Based On MOFs Materials

With the rapid development of green agriculture,the development of new biodegradable materials has become a new trend in the field of agricultural safety.In the context of rural revitalization,it is necessary to solve the agricultural security problem and realize green agriculture.Degradable membrane materials are widely used in various fields,and the application of PVA / starch degradable membrane materials in agricultural development has become a trend in agricultural development.MOFs material is a metal-organic skeleton material,which has a high specific surface area and porosity,in addition to excellent thermal stability,which can meet our various functional needs.In recent years,the research and application of MOFs materials in the adsorption field are increasing.In this topic,MOF-5 was prepared by solvent thermal method,ED ? ZIF-8 by hydrothermal method,PVA / starch film by solution flow extension method,biodegradable pesticide plastic film and fruit and vegetables by electrostatic spray technology.The specific research contents are as follows:(1)Analyze the safety problems of white pollution in the current agricultural production process to understand the safety problems existing in agriculture.The results show that the activity risk level of the resulting risk level is acceptable.The risk matrix method shows that the risk level of the experimental equipment and facility is 5and acceptable.On the basis of safety analysis,targeted safety measures are put forward to ensure the safety of personnel during the experiment.Moreover,from the composition of the experimental products and the safety of the experimental products,the results show that the composite film prepared in this study meets the characteristics of essential safety.(2)On the basis of ensuring safety,biodegradable pesticide plastic film is prepared.Based on the orthogonal test method,the best experimental conditions for MOF-5 nanoparticles synthesis were: 2.200 g zinc acetate,0.663 g terephthalic acid,DMF100 ml,control reaction temperature and reaction time were 120 ? and 24 hours,respectively.The MOF-5 nanoparticles prepared under these conditions showed a good positive hexagon shape.In order to prove their successful synthesis,the morphology and structure were characterized by SEM,TEM,FT-IR and BET.Using the constant temperature shock incubator,the best conditions for MOF-5 nanoparticles adsorption were determined by orthogonal test method: AT@MOF-5 nanoparticles at the working temperature of 35 ?,2 hours and the initial concentration of 30 mg/L,and characterized by FT-IR,SEM,TEM and BET.PVA / starch membranes were prepared by solution delay to characterized their surface morphology using SEM,optical images.A degradable pesticide plastic film was prepared by spraying pesticide-loaded MOF-5nanoparticles onto a PVA / starch film using electrostatic spray technology.(3)The adsorption behavior of MOF-5 nanoparticles was studied using adsorption isotherm and dynamics.The fitting analysis results showed that the adsorption of AT herbicide on MOF-5 was more in line with Langmuir adsorption isotherm,and the adsorption kinetic properties were most in line with the pseudo-secondary dynamics.According to the analytical results,the adsorption of AT by MOF-5 should contain a chemical process.MOF-5 adsorbed AT using an intra-particle diffusion model showed three adsorption processes for MOF-5adsorption atrazine(AT).The first stage is due to the large concentration difference between the AT solution and the MOF-5.The second process fits with intra-particle diffusion,this stage being due to the adsorption of AT in the MOF-5 pore.The last step occurs during the adsorption equilibrium phase,which is called the gradual adsorption phase due to its slow speed.In addition,the leaching characteristics of the pesticide from the biodegradable pesticide plastic film were studied,and the diffusion index fit of the Ritger-Peppas model was 1.20772,which proved that the particle release behavior is consistent with the frame erosion diffusion.(4)On the basis of ensuring safety,air-adjustable fruit and vegetable plastic wrap was prepared.ZIF-8 nanoparticles were successfully prepared using the usual hydrothermal synthesis method,using the chemical reagent dimethylimidazole with zinc nitrate hexahydrate.ZIF-8 was functionalized to be gas selective permeable.The modified reagent was ethylenediamine to explore the best conditions of modified ZIF-8 material,and ED ? ZIF-8 was sprayed on the surface of PVA / ST composite membrane by electrostatic spray.In order to improve the gas permeability and separation performance of nanocomposite film,in order to reduce the harm of non-degradable plastic film to the environment.Its bond changes are characterized by infrared spectral analysis,its crystal structure by X-ray diffraction,and its specific surface area and aperture size are characterized by BET test.It is found that when modified ZIF-8,the temperature is controlled at 60 ?,0.35 g ethylenediamine is added,and the modification time is 2 h amino modified ZIF-8.By testing the oxygen transmittance and carbon dioxide transmittance,the addition of 0.04% ED into the PVA / ZIF-8 was found best.