title: Thermochemical destruction of asbestos-containing roofing slate and the feasibility of using recycled waste sulfuric acid.
abstract: In this study, we have investigated the feasibility of using a thermochemical technique on ∼17% chrysotile-containing roofing sheet or slate (ACS), in which 5N sulfuric acid-digestive destruction was incorporated with 10-24-h heating at 100°C. The X-ray diffraction (XRD) and the polarized light microscopy (PLM) results have clearly shown that raw chrysotile asbestos was converted to non-asbestiform material with no crystallinity by the low temperature thermochemical treatment. As an alternative to the use of pricey sulfuric acid, waste sulfuric acid discharged from a semiconductor manufacturing process was reused for the asbestos-fracturing purpose, and it was found that similar removals could be obtained under the same experimental conditions, promising the practical applicability of thermochemical treatment of ACWs. A thermodynamic understanding based on the extraction rates of magnesium and silica from a chrysotile structure has revealed that the destruction of chrysotile by acid-digestion is greatly influenced by the reaction temperatures, showing a 80.3-fold increase in the reaction rate by raising the temperature by 30-100°C. The overall destruction is dependent upon the breaking-up of the silicon-oxide layer - a rate-limiting step. This study is meaningful in showing that the low temperature thermochemical treatment is feasible as an ACW-treatment method.
authors.affiliation: Engineering Research Institute, Seoul National University, Daehak-dong, Gwanak-gu 151-744, South Korea. Electronic address: namsn76@gmail.com.
authors.forename: Seong-Nam
authors.initials: SN
authors.lastname: Nam
authors.affiliation: Environmental Resource Recirculation Division, National Institute of Environmental Research, Environmental Research Complex, Kyeongseo-dong, Seo-gu, Incheon 404-708, South Korea.
authors.forename: Seongkyeong
authors.initials: S
authors.lastname: Jeong
authors.affiliation: Indoor Environment and Noise Division, National Institute of Environmental Research, Environmental Research Complex, Kyeongseo-dong, Seo-gu, Incheon 404-708, South Korea.
authors.forename: Hojoo
authors.initials: H
authors.lastname: Lim
mesh_terms: D017632:Asbestos, Serpentine / Q000737:chemistry*; D003252:Construction Materials; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D059027:Recycling; D013464:Sulfuric Acids / Q000737:chemistry*; D018505:Waste Management / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D017632:Asbestos, Serpentine; D013464:Sulfuric Acids; C033158:sulfuric acid
keywords: Asbestos containing slate; Chrysotile; Polarized light microscopy; Scanning electron microscopy; Thermochemical destruction; X-ray diffraction