title: Dual mechanochemical immobilization of heavy metals and decomposition of halogenated compounds in automobile shredder residue using a nano-sized metallic calcium reagent.
abstract: Simultaneous immobilization of heavy metals and decomposition of halogenated organic compounds in different fractions of automobile shredder residue (ASR) were achieved with a nano-sized metallic calcium through a 60-min ball milling treatment. Heavy metal (HM) immobilization and chlorinated/brominated compound (CBC) decomposition efficiencies both reached 90-100 %, after ball milling with nanometallic calcium/calcium oxide (Ca/CaO) dispersion, regardless of ASR particle size (1.0, 0.45-1.0, and 0.250 mm). Concentrations of leachable HMs substantially decreased to a level lower than the regulatory standard limits (Co and Cd 0.3 mg L-1; Cr 1.5 mg L-1; Fe, Pb, and Zn 3.0 mg L-1; Mn and Ni 1 mg L-1) proposed by the Korean hazardous waste elution standard regulatory threshold. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) element maps/spectra showed that while the amounts of HMs and CBCs detectable in ASR significantly decreased, the calcium mass percentage increased. X-ray powder diffraction (XRD) patterns indicate that the main fraction of enclosed/bound materials on ASR includes Ca-associated crystalline complexes that remarkably inhibit HM desorption and simultaneously transform dangerous CBCs into harmless compounds. The use of a nanometallic Ca/CaO mixture in a mechanochemical process to treat hazardous ASR (dry conditions) is an innovative approach to remediate cross-contaminated residues with heavy metals and halogenated compounds.
authors: Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan, 680-749, Republic of Korea.
authors: Srinivasa Reddy
authors: SR
authors: Mallampati
authors: Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan, 680-749, Republic of Korea. bhlee@ulsan.ac.kr.
authors: Byoung Ho
authors: BH
authors: Lee
authors: Department of Environmental Sciences, Prefectural University of Hiroshima, 562 Nanatsuka-Cho, Shobara City, Hiroshima, 727-0023, Japan.
authors: Yoshiharu
authors: Y
authors: Mitoma
authors: Department of Organic Chemistry, Politehnica University of Bucharest, 060042, Bucharest, Romania. c_simion@chim.upb.ro.
authors: Cristian
authors: C
authors: Simion
mesh_terms: D001336:Automobiles; D002118:Calcium / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry; D006256:Hazardous Waste / Q000032:analysis*; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D007202:Indicators and Reagents; D019216:Metals, Heavy / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D018505:Waste Management / Q000379:methods*
chemical_list: D017610:Calcium Compounds; D006256:Hazardous Waste; D006846:Hydrocarbons, Halogenated; D007202:Indicators and Reagents; D019216:Metals, Heavy; D010087:Oxides; C016538:lime; D002118:Calcium
keywords: Automobile shredder residue; Halogenated compounds; Heavy metals; Mechanochemical treatment; Nano-sized metallic calcium