THE OXIDATION OF AROMATIC HYDROCARBONS VAPORING WASTE AIR STREAMS USING VUV ADVANCED OXIDATION PROCESS
Introduction: The vacuum UV (VUV) system is a novel chemical-less advanced oxidation processes (AOP) used to decompose different class of organic contaminants. The present study aimed at investigating the efficiency of VUV process to degrade toluene as a model of aromatic hydrocarbons from the gas stream in a bench-scale photo-reactor.
Materials and methods: The effect of various parameters including radiation flux, relative humidity, toluene concentration, and ozone dosage were investigated on toluene degradation in the VUV process.
Results: The results showed that increasing the relative humidity up to 45% could considerably accelerate the oxidation of toluene as compared with the dry air stream in the process. Complete destruction of toluene was reached at radiation fluxes of 0.366 and 0.732 mJ/cm2 for 5 and 15 ppm of toluene, respectively. Dosing ozone into the VUV photo-reactor at the dosages of 20, 40 and 60 μg/s led to improve the toluene degradation from 65.6% to 100%. The removal of toluene in the VUV process under the selected optimum conditions followed a pseudo-first order reaction model with the degradation rate values of 5.99 mg/L.min.
Conclusions: It was found that VUV process might be a novel and emerging AOP, which can efficiently perform for decomposition of aromatic hydrocarbons in contaminated air stream.
Kim, J., et al., Photocatalytic degradation of gaseous toluene and ozone under UV254+185 nm irradiation using a Pd-deposited TiO2 film. Chemical Engineering Journal, 2014. 252: p. 337-345.
Huang, H., et al., Efficient degradation of gaseous benzene by VUV photolysis combined with ozone-assisted catalytic oxidation: Performance and mechanism. Applied Catalysis B: Environmental, 2016. 186: p. 62-68.
Huang, H., et al., Enhanced degradation of gaseous benzene under vacuum ultraviolet (VUV) irradiation over TiO2 modified by transition metals. Chemical Engineering Journal, 2015. 259: p. 534-541.
Águeda, V.I., et al., Effect of channel geometry, degree of activation, relative humidity and temperature on the performance of binderless activated carbon monoliths in the removal of dichloromethane from air. Separation and Purification Technology, 2011. 78(2): p. 154-163.
Tefera, D.T., et al., Modeling Competitive Adsorption of Mixtures of Volatile Organic Compounds in a Fixed-Bed of Beaded Activated Carbon. Environmental science & technology, 2014. 48(9): p. 5108-5117.
Lalanne, F., et al., Absorption of a mixture of volatile organic compounds (VOCs) in aqueous solutions of soluble cutting oil. Bioresource Technology, 2008. 99(6): p. 1699-1707.
Heymes, F., et al., A new efficient absorption liquid to treat exhaust air loaded with toluene. Chemical Engineering Journal, 2006. 115(3): p. 225-231.
Everaert, K. and J. Baeyens, Catalytic combustion of volatile organic compounds. Journal of Hazardous Materials, 2004. 109(1–3): p. 113-139.
Pengyi, Z., et al., A comparative study on decomposition of gaseous toluene by O3/UV, TiO2/UV and O3/TiO2/UV. Journal of Photochemistry and Photobiology A: Chemistry, 2003. 156(1–3): p. 189-194.
Pinard, L., et al., Oxidation of chlorinated hydrocarbons over Pt zeolite catalysts 1-mechanism of dichloromethane transformation over PtNaY catalysts. Journal of Catalysis, 2003. 215(2): p. 234-244.
Liang, W.-j., et al., Combination of spontaneous polarization plasma and photocatalyst for toluene oxidation. Journal of Electrostatics, 2015. 75: p. 27-34.
Zhou, Y., et al., Preparation of zeolitic imidazolate framework-8 /graphene oxide composites with enhanced VOCs adsorption capacity. Microporous and Mesoporous Materials, 2016. 225: p. 488-493.
Liu, Y., et al., A prediction model of VOC partition coefficient in porous building materials based on adsorption potential theory. Building and Environment, 2015. 93, Part 2: p. 221-233.
Khan, F.I. and A. Kr. Ghoshal, Removal of Volatile Organic Compounds from polluted air. Journal of Loss Prevention in the Process Industries, 2000. 13(6): p. 527-545.
Moussavi, G. and M. Mahdavianpour, The selective direct oxidation of ammonium in the contaminated water to nitrogen gas using the chemical-less VUV photochemical continuous-flow reactor. Chemical Engineering Journal, 2016. 295: p. 57-63.
Moussavi, G., et al., Comparing the efficacy of VUV and advanced oxidation processes for degradation and mineralization of cyanide in wastewater. Chemical Engineering Journal, 2016. 294: p. 273-280.
Pourakbar, M., G. Moussavi, and S. Shekoohiyan, Homogenous VUV advanced oxidation process for enhanced degradation and mineralization of antibiotics in contaminated water. Ecotoxicology and Environmental Safety, 2016. 125: p. 72-77.
Huang, H., et al., Photocatalytic destruction of air pollutants with vacuum ultraviolet (VUV) irradiation. Catalysis Today, 2011. 175(1): p. 310-315.
Zhao, W., et al., Photocatalytic oxidation of indoor toluene: Process risk analysis and influence of relative humidity, photocatalysts, and VUV irradiation. Science of The Total Environment, 2012. 438: p. 201-209.
Jeong, J., K. Sekiguchi, and K. Sakamoto, Photochemical and photocatalytic degradation of gaseous toluene using short-wavelength UV irradiation with TiO2 catalyst: comparison of three UV sources. Chemosphere, 2004. 57(7): p. 663-671.
J, Y., et al., Conversion characteristics and mechanism analysis of gaseous dichloromethane degraded by a VUV light in different reaction media. Journal of environmental sciences (China), 2012. 24(10): p. 1777-1784.
Guo, W., et al., Degradation of sulfadiazine in water by a UV/O3 process: performance and degradation pathway. RSC advances, 2016. 6: p. 57138–57143.
Yu, J., et al., Conversion characteristics and mechanism analysis of gaseous dichloromethane degraded by a VUV light in different reaction media. Journal of Environmental Sciences, 2012. 24(10): p. 1777-1784.