Study On Ethylene Remover And Equipment For Fruit And Vegetable Logistics

With the rapid development of the economy,people continue to increase the freshness requirements of fruits and vegetables.How to keep fruits and vegetables fresh during transportation and sale has become a problem in this field.It is aimed at the shortcomings of the current technology of fruit and vegetable preservation,such as incomplete removal of ethylene,low efficiency,large equipment,inability to carry it around,and high cost.In this paper,three ethylene removal methods were developed.?1?A two-dimensional sheet ethylene removal agent was prepared.This removal agent can fully wrap fruits and vegetables,and can remove ethylene in a timely and effective manner.?2?Ozone-photocatalytic degradation combined ethylene removal device was designed.The device is small in size,low in energy consumption,and the ethylene removal active component is safe and environmentally friendly.The most important thing is that the ozone and photocatalysis work together to remove ethylene more efficiently than either component alone.?3?A copper-based ethylene adsorbent was prepared.The biggest advantage of the adsorbent is that it selectively adsorbs gas in the storage environment.It can reduce the ethylene concentration through?-complexation with ethylene to achieve the preservation of fruits and vegetables.1?Potassium permanganate-based ethylene adsorption paperThe substrate is based on filter paper fibers whose surface is modified with silicon or aluminum sol and later loaded with potassium permanganate as active substance through a dipping method.We evaluated the ethylene removal efficiency by gas chromatography,and characterized the sample microstructures with scanning transmission electron microscope?scanning transmission electron microscopy,SEM-EDS?.The results showed that ethylene adsorption rate can reach 11.67%and87.00%for silicon and aluminum sol treated sample respectively,when each sample was loaded with 20 mg KMnO₄,under an initial ethylene concentration of 360?L/L for 100 min.SEM-EDS characterization showed that potassium permanganate can be evenly dispersed on aluminum sol but agglomerated as large particles on the silica sol,which may be the key factor leading to a much higher ethylene adsorption rate for aluminum sol treated samples.2?Development of ozone oxidation-photocatalytic degradation combination ethylene removal deviceWe designed a set of combination device for removing ethylene based on ozone oxidation and photocatalytic degradation and a fresh-keeping box for fruits and vegetables based on this device.The feature of the device is that ethylene removing is mainly composed of two modules,one is ozone oxidation module,the other is photocatalytic degradation module.Neither module can achieve the purpose of high efficiency,economically and a complete removal of ethylene through a single use,only can this purpose be achieved by combing these two modules.In ozone oxidation module,metal oxide is used as carrier and precious metal nanoparticles are used as active catalytic components and ethylene is initially degraded by ozone catalytic oxidation.Using small size LEDs with low heating efficiency,and strong ultraviolet radiation in 220-365 nm as excitation light sources,and nano-titanium dioxide prepared by precipitation method as a active photocatalyst,photocatalytic module can further reduce ethylene concentration in the air passing through ozone oxidation module in the previous step.Based on the combination of the above two technologies,the concentration of ethylene in the self-made storage box can be reduced until it cannot be detected by gas chromatography.3?Development of copper-based ethylene ethylene adsorbentUsing copper sulfate and copper nitrate as raw materials and reducing Cu?II?to Cu?I?by a reducing agent,a Cu-based supported type sorbent can be prepared by impregnating active components on porous material activated carbon and alumina pellets.Although the catalyst is not as efficient as supported potassium permanganate,and ozone-photocatalysis combined to remove ethylene,the adsorbent can selectively adsorb ethylene and has no effect on other gases in the storage environment?for example,it can continue to maintain high Concentration of carbon dioxide?...