Design and optimization of fluidized bed photoreactor for ethylene reduction within cold storage room for fruits and vegetables using Ti02-based materials

摘要

Ethylene (C2H4) occurrence in cold storage room for fresh fruits and vegetables could be detrimental due to its effects on plant tissue. Softening enhancement, chlorophyll losses, senescence acceleration and browning are the most common symptoms of ethylene presence in the atmosphere surrounding products. A fluidized bed photoreactor (FBP) was designed and its activity in decomposing ethylene using titanium oxide (Ti02)-based materials was studied. Several factors were studied in order to maximize the FBP degradation rate of the plant hormone. In order to design and manufacture the reactor, gas flow rate per unit of reactor volume, photocatalyst characterization, geometry of the reactor and UV lamps location were optimized. The unit was equipped with a UV-A-transparent glass tubular reactor in which the photo-oxidation of ethylene by means of photocatalytic material took place. Different photocatalytic materials were synthesized and tested (Alumina-TiCh/SiCh and Degussa P25 microparticles). The degradation efficiency of the different catalysts was investigated by measuring the percentage of reduction of C2H4 in the reaction chamber during the experiments in recirculation mode. Among the materials, Degussa P25 microspheres showed the highest photocatalytic activity allowing complete elimination of ethylene in the treated atmosphere after 160 min. Using this material CzH4 reduction was clearly dependent on UV light exposure. FBP was installed within a cold room simulating fresh produce storage conditions. Transfer of photocatalytic technology could be useful for the fruit processing industry in order to avoid ethylene adverse effects on physical, nutritional and sensorial quality of fresh and minimally processed fruits and vegetables.