Photoelectrocatalytic degradation of ethylene by a combination of TiO 2 and activated carbon felts

Abstract

Postharvest loss of quality is an important problem in the food and horticultural product industry. One of the major factors contributing to loss of quality is the uncontrolled exposure of the products to small amounts of ethylene gas during storage. In this study we investigated the photoelectrocatalytic (PEC) degradation of ethylene gas at a temperature of 3 ± 1 °C and relative humidity of 90 ± 3% on an activated carbon felts (ACF)-supported photocatalyst titanium dioxide photoelectrode [TiO 2/ACF] or on a photoelectrode which had been modified by coating the ACF support with platinum [TiO 2/ACF-Pt]. The apparent pseudo-first-order kinetic model was used to describe the PEC degradation of ethylene. The key designing parameters for a PEC reactor affecting the degradation efficiency in terms of the rate constant of this model were studied, including the bias voltage and the light intensity. Degradation of ethylene by applying a bias voltage to the [TiO 2/ACF] |Nafion|[TiO 2/ACF] electrode-membrane assembly or to the [TiO 2/ACF-Pt] |Nafion|[TiO 2/ACF-Pt] electrode-membrane assembly enhanced the efficiency of photocatalytic (PC) degradation. The combination of the ACF support modified with platinum and the applied bias voltage were found to have an additive enhancement effect on the rate constant compared to PEC degradation carried out using the unmodified ACF support. With respect to the [TiO 2/ACF-Pt] |Nafion|[TiO 2/ACF-Pt] electrode-membrane assembly, a kinetic model was established using response surface methodology to describe the relationship between the rate constant and the affecting parameters. Optimized parameters were found to be a light intensity of 3.1 mW cm −2 with a bias voltage of 47.5 V.