title: Combination of advanced oxidation processes and gas absorption for the treatment of chlorinated solvents in waste gases.
abstract: Treatment of chlorinated organic compounds in waste gases is difficult because of several reasons: these compounds are dioxin precursors when incinerated, and also biological treatment is difficult because of a limited number of suitable microbial degradation pathways. On the other hand, since the 1990s, a new generation of chemical oxidation techniques has been introduced in water treatment. Advanced Oxidation Processes (AOPs) are based on a combination of UV/H202, UV/O3 or H2O2/O3. The combinations result in the generation of OH-radicals, which subsequently attack the organic pollutants. In this work, the treatment of a gas stream (240 L/h) loaded with 20-40 ppmv trichloroethylene (TCE) is presented. Therefore, a combination of an absorption process in a bubble column with a liquid H2O2/O3 initiated oxidation, was investigated. Removal efficiencies, depending on the dosed H2O2 and O3, up to 94% were found. The production of chloride ions was investigated: the Cl-atoms from the removed TCE could be found back as chloride ions. Next to the experimental work, attention was paid to the mechanisms taking place in the proposed concept. Here, a simulation model was developed, considering gas/liquid mass transfer of TCE and ozone, axial liquid dispersion, advective gas and liquid transport and about 29 chemica reaction steps. The modelling allowed a better understanding of the technique and gives insight in its possibilities and limitations. Finally, it can be concluded that the proposed technique shows interesting perspectives: it is able to transform chlorine in chlorinated solvents into chloride ions effectively at ambient temperature conditions.
authors.affiliation: Department of Organic Chemistry, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Coupure Links 653, G-9000 Ghent, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Dewulf
authors.forename: H
authors.initials: H
authors.lastname: Van Langenhove
authors.forename: E
authors.initials: E
authors.lastname: De Smedt
authors.forename: S
authors.initials: S
authors.lastname: Geuens
mesh_terms: D000042:Absorption; D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000517:prevention & control*; D017606:Chlorine Compounds; D005740:Gases; D006861:Hydrogen Peroxide / Q000737:chemistry; D017745:Incineration; D008962:Models, Theoretical; D016877:Oxidants / Q000737:chemistry; D010083:Oxidants, Photochemical / Q000737:chemistry; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D014241:Trichloroethylene / Q000737:chemistry; D014865:Waste Disposal, Fluid
chemical_list: D000393:Air Pollutants; D017606:Chlorine Compounds; D005740:Gases; D016877:Oxidants; D010083:Oxidants, Photochemical; D012997:Solvents; D014241:Trichloroethylene; D010126:Ozone; D006861:Hydrogen Peroxide