Study On 5A Zeolite Material Modified By TiO₂ And Its Adsorption Properties For Space Molecular Pollutants

Non-metallic materials for spacecraft will produce small organic molecule condensable volatiles in the space environment,condensing on sensitive surfaces such as optical lenses and solar cells,which has a great impact on the safety and reliability of the spacecraft.Active control of pollutants using adsorbent materials is one of the effective means to solve the pollution of space molecules.Zeolite material has a uniform pore size distribution and excellent adsorption performance,which is one of the ideal materials for the adsorption of space molecular pollutants.However,its mechanical strength is poor,and the adsorption performance of space molecular pollutants still needs to be improved.Therefore,there is an urgent need to develop new space molecular pollutant adsorption materials with high adsorption performance and good mechanical properties.In this paper,through the integrated research on the design,preparation,adsorption performance and adsorption mechanism of modified zeolite materials,zeolite@TiO₂ composite materials with high adsorption performance were prepared,which provided theoretical and technical basis for the selection and application of space molecular pollutant adsorption materials.Atomic layer deposition technology was used to prepare TiO₂,and the influence of process parameters such as titanium source time,process pressure,source bottle temperature and reaction chamber body temperature on film formation was studied,and zeolite@TiO₂ was characterized by AFM,XPS,TEM,SEM,XRD,etc.The elemental composition,morphology and structure of TiO₂ composite materials can obtain the optimal process parameters.According to the adsorption amount of zeolite@TiO₂ composite material,the optimal pretreatment process was determined as vacuum extraction,heating at 200 ? and holding for 120 min.The adsorption properties of zeolite@TiO₂ were studied under different experimental conditions to determine the optimal process parameters.The titanium source Dose time was 0.2 s,the source bottle temperature was 82 ?,the deposition temperature was 200 ?,and the materials prepared during the deposition of 200 cycle had the best adsorption performance and High mechanical strength.The experimental results show that the adsorption capacity of zeolite@TiO₂ within 3 hr is about 16.5 mg/g,which is about 4 mg/g higher than that of 5A zeolite without any treatment,and 2 mg/g higher than that of 5A zeolite after pretreatment.The strength is also improved compared to 5A zeolite.The BET test shows that the specific surface area of zeolite@TiO₂ is increased by 17.71% and the pore diameter is reduced by 0.2 nm than that of 5A zeolite.The combined effect of the two sides makes the performance of TiO₂ modified zeolite material improved.Using Materials Studio software to build models of typical space molecular contaminants dimethyl phthalate and diethyl phthalate,using Monte Carlo method and molecular dynamics method to simulate the adsorption of these two gases by 5A zeolite Performance,get its adsorption law under different pressure and temperature.The results show that at the same temperature,with the increase of pressure,the adsorption capacity of these two gases is increasing.At 125 ? the adsorption capacity is the largest.The density distribution of the gas in 5A zeolite indicates that the adsorption of gas is mainly in the 5A zeolite eight-membered ring cage.Simulating the adsorption isotherms and adsorption heat data of the two gases determines that the adsorption process is directly related to the molecular weight of the gas.The pore size of the zeolite is fixed,when the molecular weight of the gas is larger,the adsorption amount is smaller,and the adsorption heat is greater.The above research provides new ideas for the prevention and control of space molecular pollution from both experimental and theoretical aspects.