Photodegradation of cyclohexane and toluene using TiO2/UV/O3 in gas phase

Abstract

Volatile organic compounds (VOC) are air pollutants usually found in urban and industrial areas. Heterogeneous photocatalysis is an interesting technique used to degrade these compounds. Several approaches may enhance this process; some studies have shown higher VOC conversions by adding ozone to the experimental system, once ozone increases the number of reactive radicals in the reaction. In this context, this work studied the conversion of cyclohexane and toluene by heterogeneous photocatalysis in gas phase, in the presence of titanium dioxide (TiO), UV light, and different concentrations of ozone. For fixed space times from 13.1 to 48.8 s, an average increase of 9% was reached in cyclohexane conversion when comparing the system with maximum concentration of ozone (0.8%) and the system without it. In addition, difference of less than 2% in the conversion of cyclohexane with different moisture fractions was observed. Toluene photodegradation was also analyzed in the presence of ozone and although the conversion was only about 40% for the space time of 25 s, this result was maintained during 4 h of experiment, with no catalyst deactivation as usually reported in the literature for aromatic compounds. Based on the results, ozone addition is an advantageous technique to improve the photodegradation of VOC.

Phase/Size‐Controlled Synthesis of Nanostructured PbO2Microspheres for Efficient Electrochemical Ozone Generation

“…According to the suggested mechanism as shown in Equations (8)(9)(10)(11)(12)(13), as oxygen evolution and O 3 generation occur simultaneously during water splitting process on PbO 2 electrode under high anode potential. Due to the lower standard electrode potential of O 2 /H 2 O redox couple (1.23 V) than O 3 /H 2 O (1.51 V), O 2 is generally the main product of water splitting process.…”

“…As a very strong oxidizing agent, ozone (O 3 ) can easily decompose into harmless oxygen (O 2 ). These features render O 3 a powerful and environmentally clean oxidant in water treatment, bleaching and disinfection industries [6,12–14] …”

“…The development of industrial activities has given rise to growing concerns about environmental pollution such as dyeing wastewater, textile wastewater and volatile organic compounds (VOCs). [1][2][3][4][5][6][7][8][9] Researchers have been urged to find more clean and efficient methods to eliminate the hazardous and toxic materials such as adsorption, microbial degradation and advanced oxidation process et al [3,[5][6][7][8][10][11][12][13] As a very strong oxidizing agent, ozone (O 3 ) can easily decompose into harmless oxygen (O 2 ). These features render O 3 a powerful and environmentally clean oxidant in water treatment, bleaching and disinfection industries.…”

“…These features render O 3 a powerful and environmentally clean oxidant in water treatment, bleaching and disinfection industries. [6,[12][13][14] Due to the low energy demand, corona discharge technology is usually used to produce O 3 . [15][16][17][18][19] As an alternative technology, electrochemical ozone production (EOP) can produce O 3 with much higher concentration, and thus is more suitable for small-scale applications.…”

Investigation of cyclohexane catalytic degradation driven by N atoms from N2 discharges

“…While, atomic nitrogen (N 2 D) has a relative retention time as long as ≈17 h; even the N 2 P has a relative retention time of about 12 s, higher than that of molecular nitrogen (N 2 A 3 Σ u ) τ 0 =2.0 s [16]. Oxygen species, such as O( As a typical VOC, cyclohexane mainly comes from the volatile waste gas when it is used as a solvent as well as the discharge during nylon manufacturing [20,21]. A recent paper reported that the repeated inhalation of cyclohexane can produce steady hyperactivity and reduce ataxia, sedation, and seizures as the exposure to cyclohexane progressed [22,23].…”