title: Decomposition of organochlorine compounds in flue gas from municipal solid waste incinerators using natural and activated acid clays.
abstract: High-temperature particle control (HTPC) using a ceramic filter is a dust collection method without inefficient cooling and reheating of flue gas treatment; thus, its use is expected to improve the energy recovery efficiency of municipal solid waste incinerators (MSWIs). However there are concerns regarding de novo synthesis and a decrease in the adsorptive removal efficiency of dioxins (DXNs) at approximately 300 degrees C. In this study, the effect of natural and activated acid clays on the decomposition of monochlorobenzene (MCB), one of the organochlorine compounds in MSW flue gas, was investigated. From the results of MCB removal tests at 30-300 degrees C, the clays were classified as adsorption, decomposition, and low removal types. More than half of the clays (four kinds of natural acid clays and two kinds of activated acid clays) were of the decomposition type. In addition, the presence of Cl atoms detached from MCB was confirmed by washing the clay used in the MCB removal test at 300 degrees C. Activated acid clay was expected to have high dechlorination performance because of its proton-rich-composition, but only two clays were classed as decomposition type. Conversely, all the natural acid clays used in this work were of the decomposition type, which contained relatively higher di- and trivalent metal oxides such as Al2O3, Fe2O3, MgO, and CaO. These metal oxides might contribute to the catalytic dechlorination of MCB at 300 degrees C. Therefore, natural and activated acid clays can be used as alternatives for activated carbon at 300 degrees C to remove organochloride compounds such as DXNs. Their utilization is expected to mitigate the latent risks related to the adoption of HTPC, and also to contribute to the improvement of energy recovery efficiency of MSWI. Implications: The effect of natural and activated acid clays on MCB decomposition was investigated to evaluate their suitability as materials for the removal of organochlorine compounds, such as DXNs, from MSWI flue gas at approximately 300 degrees C. More than half of the clays used in this study showed the decomposition characteristics of MCB. The presence of Cl atoms in the clay used in the MCB removal test at 300 degrees C proved the occurrence of MCB decomposition. The results of this study suggest a novel flue gas treatment method to establish high-energy efficient MSWI systems.
authors.forename: In-Hee
authors.initials: IH
authors.lastname: Hwang
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Takahashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsuo
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Matsuto
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D000538:Aluminum Silicates / Q000737:chemistry*; D002947:Cities; D000077215:Clay; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017745:Incineration / Q000379:methods*; D013696:Temperature; D014835:Volatilization
chemical_list: D000393:Air Pollutants; D000538:Aluminum Silicates; D006843:Hydrocarbons, Chlorinated; D000077215:Clay