Study On Photocatalytic Decomposition Of Ethylene In Fruit Preservation Field

Improper preservation will make the fruit rotten deterioration in the fruit preservation process.And because of rotting deterioration,people will lose more than 30%of the total output value every year in our country.Ethylene content is one of the important indicators in fresh fruit environment controlling process.TiO₂ can decompose ethylene under photocatalytic conditions,so in this paper,the photocatalytic technology what we use was applied in the field of fruit preservation.We carried out the research on the TiO₂ film ethylene decomposition and plasma surface modification,and explored the effective method to improve the photocatalytic activity of Ag⁺doped TiO₂.?1?Ag⁺doped TiO₂ films were prepared by sol-gel method and impregnation method.The results show that the thickness of TiO₂ film is proportional to the number of layers.When the heating rate is 10?/min,15?/min and 20?/min,the particle size of the obtained TiO₂ film is 9nm,17nm and 59nm respectively.When the heating rate of the TiO ₂is slower,it will make the crystal particles smaller,and make the specific surface area larger,which is favorable for the photocatalytic oxidation reaction.When the transmittance is converted to absorbance,it can be seen that the absorbance of Ag⁺doped TiO₂ thin film reaches the highest point at 350nm,and drops rapidly to the bottom after 423nm.?2?Study on the effects of ethylene photocatalytic decomposition,include the TiO₂thin films'contact area,the layers'numbers and the crystal crystallinity,then design single factor experiment.The results show that the light intensity,contact area and crystal crystallinity can change the ethylene decomposition capacity of TiO ₂ significantly.When the light intensity is higher,or the contact area is greater or the crystal gain size is smaller,the rate of film's ethylene decomposition will be higher.When the UV tube power is 8W,the ethylene decomposition efficiency of the 7th layer is the highest.When the UV tube power is 4W,the ethylene decomposition efficiency of the 5th layer TiO ₂ film is the highest.The results of storage test of banana showed that Ag⁺supported TiO₂ film could reduce the content of ethylene in banana storage environment effectively,can make the color of banana epidermis was slower and yellowing,so as to prolong the shelf life.?3?By XRD and IR spectrum analysis,the results show that the TiO₂ film has a very obvious nitrogen doping phenomenon after nitrogen plasma treatment,and XRD shows that the surface of the film appeared a new phase Ti₂-O-N₂ and the crystal particles become smaller.The TiO₂ thin film's transmittance will be changed after plasma surface treatment.The film with nitrogen plasma treatment for 1 minute had the lowest transmittance and the highest absorbance in the same wavelength range.The TiO ₂ thin films'band gap is narrowed after plasma treatment.This shows that nitrogen low temperature plasma surface treatment can enhance the TiO₂ film's ethylene decomposition capacity.The results of orthogonal test show that when the films'area is 208.47cm²?9 films?,and plasma surface treatment's time is 1 minute and the layers number is 5,the TiO₂ films'ethylene decomposition ability is the best.