Preserving the quality of agricultural products via the photocatalytic decomposition of ethylene in a spiral-type reactor

Abstract

The photocatalytic decomposition of ethylene in a spiral-type reactor was investigated to develop a method for preserving the quality of agricultural products. Ethylene was injected or discharged from an apple into a 0.016 m3 closed container and was photocatalytically decomposed in the reactor at 25 °C. The results indicated that ethylene was decomposed and became undetectable (the amount of ethylene was lower than the detection limit of 40 ppb), which is useful for preserving the quality of agricultural products over long periods of time. For the demonstration experiment, we placed an apple, a persimmon, a cucumber, a cabos (Citrus sphaerocarpa), and a banana in a 0.117 m3 closed container at 25 °C. When the air inside the container was not photocatalytically treated, the concentration of ethylene increased up to 2.7 ppm. This lowered the quality of the persimmon, cucumber, and apple significantly. In contrast, when the air inside the container was photocatalytically treated, they remained fresh for at least nine days. Methane was simultaneously generated as a byproduct. It was hypothesized that methane was the product of the photocatalytic decomposition of some unknown chemical compound released from the analyzed agricultural products; however, we were unable to identify the chemical compound. Computer simulations using experimentally determined parameter values suggested that the decomposition of ethylene begins before or as soon as agricultural products are stored in closed rooms, such as truck containers. In conclusion, the photocatalytic decomposition of ethylene using a spiral-type reactor is effective for preserving the quality of agricultural products.