Abstract:
Abstract: Fruits and vegetables can produce large amounts of ethylene when stored in an enclosed storage space after harvest, which can accelerate the maturity and aging of fruits and vegetables. Due to the existence of ethylene in closed storage environment and inappropriate storage methods, a large amount of horticultural products is deteriorated, resulting in huge economic losses every year. Because of large surface area, stable chemical property, excellent charge transport characteristic and available recycling properties, TiO2 nanotube arrays (TNTAs) have been used widely in sensors, dye-sensitized solar cells, light catalytic cracking water into hydrogen, degradation of organic pollutants and other related fields. Even though the formation of TNTAs are highly ordered and vertical growth on titanium substrate, the recombination of photo-generated electrons and hole pairs at the surface of TNTAs is an issue, which seriously limits the catalytic efficiency for ethylene degradation. In order to study the influence of semiconductor materials of titanium dioxide nanotube arrays modified with Ag-doped and 60Co γ-ray irradiation on photocatalytic degradation of ethylene in cold storage environment, we prepared TNTAs with anodic oxidation method followed with60Co γ-ray irradiated on it for modification. Anodic oxidation method can be used to prepare titanium dioxide nanotube arrays with different dimensions conveniently through controlling anode potential, electrolyte concentration, and temperature, which have been considered as one of the most popular ways for enhancing the photocatalytic efficiency of TiO2. Gamma rays have been observed to play a key role in inducing disruption and dislodgement of electrons and sometimes atoms within a crystal to create defects in the crystal structure. After the formation of TNTAs, silver nanoparticles were made by irradiated reduction technology and doped on TNTAs to make up the new photocatalytic material of TNTAs-Ag. The addition of Ag nanoparticles can make photo-generated electrons transfer from a higher energy level of TiO2 to the noble metal with a lower Fermi level so that the electrons and holes can be separated rapidly.Field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to analyze the characterization of the prepared semiconductor materials. Results showed that: irradiated modification can transfer amorphous crystal of TNTAs to anatase crystal. The diffraction peak of anatase crystal becomes more and more sharp and the crystal dimension becomes smaller and smaller with the increase of irradiation dose, indicating that silver particles adhered to the nozzle of TNTAs in the form of cluster deposition and it didn't not enter internal wall after doping the surface of TNTAs. Experiments of photocatalytic degradation of ethylene with TNTAs and TNTAs-Ag under ultraviolet in simulating cold storage environment were also conducted, where rate constant K′ was chosen to represent the degradation ability of ethylene. It turned out that: optimal rate constant K′ can reach up to 2.03×10-4 min-1 when TNTAs were irradiated under 20 kGy. After modifying Ag on irradiated TNTAs, the rate constant K′ increased by 189.66% compared with irradiated modification separately, the constant was 5.88×10-4 min-1.