Photo-catalytic oxidation of individual and mixture of benzene, toluene and p-xylene

Abstract

Photo-catalytic degradation of volatile organic compounds [VOCs: benzene, toluene and p-xylene (BTX)] was investigated using a batch reactor having a TiO 2 (catalyst)-coated aluminum sheet and a source of UV light (sunlight or UV lamp). To study the photo-oxidation, experiments were conducted under the following configurations: (1) TiO 2 (m): microparticle (0.32-3.31 lm) and sunlight (2) TiO 2 (n): nanoparticle (0.80-4.70 nm) and sunlight, (3) TiO 2 (m) and UV lamp and (4) TiO 2 (n) and UV lamp. Degradation of BTX followed first-order decay for individual compounds. The degradation rate constant in min -1 cm -2 (coated surface area) was the highest for configuration (4) (benzene 1.07 9 10 -3 , toluene 1.36 9 10 -3 and p-xylene 2.93 9 10 -3 ) followed by configuration (2), thus indicating the importance of particle size of the catalyst in degradation. Degradation of BTX mixture did not follow first-order decay. Benzene was an intermediate product of oxidation of toluene. Benzene and toluene were intermediate products of oxidation of p-xylene. For degradation of BTX mixture, a mathematical model was proposed to predict concentrations as a function of time. Experimental and model results showed similar trends in BTX degradation. The model accounted for increases in mass of toluene and benzene due to the degradation of p-xylene.

Experimental and modeling study of visible light responsive photocatalytic oxidation (PCO) materials for toluene degradation

“…One possible reason is our use of low concentrations: most studies aimed at observing by-products have used test gases with much higher VOC levels, e.g., hundreds of ppm [33–38]. A second possible reason is the small volume sampled on the adsorbent tube (selected so as not to overload the GC/MS with toluene) that may have limited sensitivity for the generated by-products (possible in the pg range).…”

“…Most evaluations have focused on NO x (NO, NO 2 ) removal using UV lights for outdoor applications [27–32]. Several studies have evaluated VOC removal (e.g., ethanol, heptane, decane, benzene, toluene, p- xylene, and acetone) at relatively high concentrations, e.g., tens to hundreds of ppm [33–38], but these levels are well above those usually encountered outside relatively few industrial environments. Other studies have evaluated VOC removal using heated PCO reactors [39, 40], which are not suitable for indoor applications and which have other cost and environmental issues, and to date, field studies of commercial PCO-based products have not demonstrated VOC removal [41, 42].…”

“…For example, degradation of benzene by O 3 -assisted PCO has been shown to form octane, decane, nonane, decanal, and decanoic acid (all in gas-phase), as well as (solid phase) p-benzoquinone [43]. PCO degradation of toluene formed benzene, and degradation of p- xylene produced both benzene and toluene [38]. Under simulated solar irradiation, TiO 2 -based paints exposed to n-decane formed C6–C11 alkanes, 4-methylnonane, 2,6-dimethyloctane, butanoic acid, propanoic acid and butanal [44].…”

Occupational hazards in printing industry

“…In addition, many VOCs, present in higher concentrations in indoor environments, are considered to be toxins, carcinogens, or mutagens or to be responsible for allergic symptoms, such as asthma or eczema. Their adverse effect on air quality and human health are cause for very careful control Ji et al 2008;Kumagai et al 2013;Su et al 2013;Dhada et al 2015;Kommalapati et al 2015;Venkanna et al 2015).…”

“…IPA added to the fountain solution evaporates into the ambient air and contributes to the release of pollutants from the group of volatile organic compounds (Svendsen and Rognes 2010;Kiurski et al 2013a). Further, VOCs can contribute to the formation of new oxidation products and secondary aerosols that can cause sensory irritation symptoms (Dhada et al 2015).…”