Decomposition of ethylene in cold storage by plasma-assisted photocatalyst process with TiO2/ACF-based photocatalyst prepared by gamma irradiation

Abstract

A direct-current corona discharge plasma-assisted photocatalyst (PAC) system was developed for ethylene degradation in simulated cold-storage conditions. Titanium dioxide (TiO2; P25 from Degussa) and TiO2 treated by γ-irradiation (TiO2∗), as well as TiO2∗ photocatalyst combined with Ag nanoparticles produced by reduction using γ-radiolysis [Ag+TiO2∗], loaded on activated carbon fiber (ACF) were prepared. The changes in the crystallographic and physicochemical characteristics in the photocatalysts, induced by γ-irradiation and doping with Ag, were investigated using analytic techniques: electron microscopy (transmission electron microscope, scanning electron microscope and field emission scanning electron microscope), X-ray diffraction and X-ray photoelectron spectroscopy. We compared the performance of three photocatalyst films concerning ethylene decomposition, ozone formation and energy efficiency. The use of TiO2∗/ACF and [Ag+TiO2∗]/ACF as post plasma photocatalyst films led to a higher ethylene decomposition rate constant and a lower emission of the by-product ozone than for TiO2/ACF. The PAC process with [Ag+TiO2∗]/ACF had the highest performance of the three photocatalysts. The results could be explained by the impact of the crystallographic and physicochemical characteristics of photocatalysts, such as anatase and rutile relative amounts, crystallite dimension, hydroxyl radical groups and Ti3+ on the surface, and the Schottky barrier at the Ag-photocatalyst contact region.