Investigation into Photocatalytic Degradation of Gaseous Ammonia in CPCR

Abstract

Addition of urea-based antifreeze admixtures during cement mixing in construction of buildings has led to increasing indoor air pollution because of continuous transformation and emission of urea to gaseous ammonia on indoor concrete walls. To control ammonia pollution from indoor concrete walls, a circulated photocatalytic reactor (CPCR) was designed to intensify the performance for the decomposition of gaseous ammonia in the present study and TiO 2 film photocatalysts were prepared by the sol-gel method and coating onto the inner wall of this reactor using a bonder of polyacrylic ester emulsion, which was characterized by FTIR, TEM, and SEM. In particular, the influences of initial concentration of ammonia on the degradation conversion (D p ), apparent reaction rate constants (k r ), initial degradation rate (r), deactivation, and regeneration of catalyst in CPCR were investigated. Furthermore, a designed equation of surface catalytic kinetics was developed for describing the decomposition of ammonia in CPCR. The total number of adsorption sites available for the gas molecules N T and the adsorption equilibrium constant K ads values were determined through a linearfitting method. Finally, undesirable NO 2 and NO 3 were detected as the intermediates in the process of photodegradation at different initial concentration of ammonia, which was detected by catalytic kinetic spectrophotometry. The results indicated that the degradation conversion (D p ), initial degradation rate (r), degraded products, and half-life (t 1/2 ) were closely correlated to the initial concentration of ammonia. It was found that the reaction kinetics fixed the pseudofirst-order kinetic equation of photocatalytic degradation of gaseous ammonia in CPCR, and the kinetic results are discussed in terms of adsorption of ammonia and products degraded.

Photocatalytic oxidation of gaseous ammonia over fluorinated TiO2 with exposed (001) facets

“…A few studies have been focused on the photocatalytic removal of gaseous NH 3 . Several types of modified TiO 2 -based photocatalysts such as TiO 2 -activated carbon composites [12,13], woven fabric-supported P25 [14,15] and latex paint-supported film nano-TiO 2 [16,17] have been evaluated for the PCO of NH 3 under UV light irradiation. The product distribution during the PCO of NH 3 has been investigated by FTIR or GC/GC-MS, and N 2 was found to be the main gaseous product; N 2 O, NO 2 − and NO 3 − were registered as the major by-products [12,[18][19][20].…”

Production of Copper-Based Rare Earth Composite Metal Materials by Coprecipitation and Applications for Gaseous Ammonia Removal

“…[1][2][3][4] Typical biological and physicochemical treatments, which use biofilters, stripping, scrubbing with water, postcombustion controls, and electrochemical oxidation methods, all induce a phase transformation and may yield contaminated sludge or adsorbent that requires further treatment. The maintenance and operating costs associated with these physical and chemical methods are high.…”

Performance of Air Fresher System for the Removal of Various Odorants Released from Foodstuffs

“…However, the reliability of AF systems with respect to odorant species has been poorly validated (Kim et al, 2010;Choi et al, 2002). So far, the most commonly employed means of mitigating odor pollution is decomposition by photocatalysis (Huang et al, 2015;Yu et al, 2013;Mo et al, 2009;Geng et al, 2008;Hodgson et al, 2007;Sakai et al, 2006;Ao and Lee, 2005;Kataoka et al, 2005;Oh, 2003;Zhao and Yang, 2003). However, in light of the inherent shortcomings of AF systems (such as high cost, low availability, lack of portability, eye irritation etc.…”