Removal of Ethylene and Secondary Organic Aerosols Using UV-C254 + 185 nm with TiO2 Catalyst

Abstract

In this investigation we evaluated the feasibility and effectiveness of ozone-producing UV (254 + 185 nm) irradiation and a TiO 2 photocatalyst for degradation of ethylene, which is strongly hydrophobic and does not decompose easily in a humid environment. Tests were performed in a photoreactor (V = 0.55 L) under UV irradiation at various wavelengths (365, 254 and 254 + 185 nm), relative humidities (RH < 1% and RH > 86%), atmospheres (pure N 2 and air), residence times (11-33 sec), initial ethylene concentrations in the range of 25-105 ppmv and TiO 2 contact areas (86.4-259 cm 2 ) with presumably ambient pressure and temperature.The experimental results demonstrated that the use of TiO 2 under 254 + 185 nm UV irradiation significantly enhanced the photodegradation of ethylene compared to the case of UV irradiation alone, due to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the TiO 2 surface. Photodegradation induced with 254 + 185 nm UV irradiation was compared with photodegradation induced with UV irradiation at wavelengths of 365 and 254 nm. The highest conversion and mineralization levels were obtained with 254 + 185 nm UV irradiation among the three tested UV sources. Moreover, irradiating with 254 +185 nm light generated secondary organic aerosols (SOA) via gas-to-particle conversion of organic compounds in the air stream. The results indicate that the concentration of generated SOAs decreased in the presence of the TiO 2 catalyst, and thus that TiO 2 may be used to effectively control the emissions of undesirable SOAs.In an application test, for photocatalytic oxidation with 254 + 185 nm UV irradiation, corresponding to a flow rate of 0.5 L/min, and an initial concentration of 34 ppmv, over 90% of the inlet ethylene could be degraded.

Impact of vacuum ultraviolet (VUV) photolysis on ethylene degradation kinetics and removal in mixed-fruit storage, and direct exposure to ‘Fuji’ apples during storage

“…Additionally, high contents of ethylene might suppress the transmission of 185 nm UV light, thereby reducing the production of the HO ● radicals responsible for ethylene oxidation (Gómez Pacheco et al 2012 , Yao et al 2016 ). These results are in accordance with the work of Chang et al ( 2013 ) where the authors reported a decrease in ethylene percentage removal from 63 to 40% upon increasing initial concentration from 20 to 100 mg/kg. The removal of ethylene by VUV photolysis can be said to be a first-order reaction that is dependent on the initial ethylene concentration.…”

Synthesis, characterization and application of naïve and nano-sized titanium dioxide as a photocatalyst for degradation of methylene blue

“…This powder shows a dramatic increase in photocatalytic action and increased strength, hardness and cutting efficiency. TiO 2 is an excellent material for photocatalytic applications, such as the remediation of pollutants, water splitting, the destruction of highly toxic molecules, the selective and synthetically redox transformations, the production of hydrogen, and for the conversion of solar energy to electric power [15,16].…”

A review of prospects and challenges of photocatalytic decomposition of volatile organic compounds (VOCs) under humid environment

“…[143] The photodegradation of ethylene was studied using UV (254 + 185 nm) irradiation and a TiO 2 photocatalyst. It was observed that using UV irradiation considerably improved the photodegradation of ethylene by Chang et al [144] Jeong et al [145] studied the degradation of NO x and toluene by means of UV-C254 + 185 nm/TiO 2 irradiation and reported that NO x and toluene were effectively degraded to HNO 3 and CO 2 , respectively.…”