Adsorption performance of titanium dioxide (TiO2) coated air filters for volatile organic compounds

Abstract

The photocatalytic oxidation (PCO) technology as an alternative method for air purification has been studied for decades and a variety of PCO models indicate that the adsorption of reactants on the catalyst surface is one of the major physical and chemical processes occurring at a heterogeneous photocatalytic reaction. However, limited study explored the adsorption effect of a photocatalyst. This study carried out a systematic evaluation of adsorption performance of titanium dioxide (TiO(2)) coated fiberglass fibers (FGFs), TiO(2) coated carbon cloth fibers (CCFs), and original CCFs air filters at various relative humidity conditions for nine volatile organic compounds. TiO(2)/FGFs, TiO(2)/CCFs, and CCFs were characterized by SEM for morphology and N(2) adsorption isotherm for BET surface area and pore structure. A bench-scale adsorption test setup was constructed and adsorption tests were performed at various relative humidity conditions and four different injected concentrations for each compound. The isothermal adsorption curves at low concentration levels were obtained and they were well described by Langmuir isotherm model. It was noticed that there were significant differences between the adsorption behaviors and photocatalytic activities of TiO(2)/FGFs and TiO(2)/CCFs. It was concluded that adsorption performance is closely related to the characteristics of substrates and therefore, the development of a substrate with high adsorption ability is a promising trend for improving the performance of the UV-PCO technology.

Deactivation and ultraviolet C-induced regeneration of photocatalytic oxidation air filters

“…It should be noted that higher amounts of gaseous byproducts were generated from TiO 2 -fiberglass filters than those from TiO 2 -carbon cloth filters for both acetone and MEK regeneration tests (shown in Figures 6 and 7). It further proves the previous finding that substrate property plays a certain role on chemical adsorption, PCO conversion, and regeneration performance (Zhong et al 2012). 6.…”

“…After introduction of a higher humidity, the acetone production rate gradually decreased, which verifies again that a high humidity helps to accelerate the regeneration rate for two substrates. Moreover, a decrease of adsorption capacity of acetone with humidity is another reason to expel acetone from PCO filters (Zhong et al 2012).…”

Using physical–chemical properties of reactants to estimate the performance of photocatalytic oxidation air cleaners

“…(14) can be shown in simplified form as: C ads ¼ C max $KC eq , where C max $K depends on the maximum monolayer surface coverage of the adsorbing species. The term, C ads /C max , can be replaced with the mass ratio of the adsorbed VOCs to the catalyst (m VOC /m catalyst ) at adsorption equilibrium per unit weight of test catalyst media [24]:…”

Evaluation of nano-titanium dioxide (TiO2) catalysts for ultraviolet photocatalytic oxidation air cleaning devices

“…These structural features have drawn considerable 14 interest to use merely this compound or combine with other noble 15 metal elements to obtain higher photocatalytic reaction rate [1][2][3][4][5]. 16 The previous studies pointed out that the photoactivity of TiO 2 is 17 mainly attributed to its distinctive particle morphology, particle 18 size, high UV absorption, wide energy band gap and high surface 19 area [6][7][8][9]. Moreover, the presence of anatase phase and 20 combination of anatase and rutile properties together made it 21 possible to undergo surface reactions induced by lower activation 22 energy [10].…”