title: Mechanochemical degradation of γ-hexachlorocyclohexane by a planetary ball mill in the presence of CaO.
abstract: Although the use of the insecticide γ-hexachlorocyclohexane (HCH) is now prohibited in many countries because of its hazardousness, stockpiles of γ-HCH still exist. In this study, we subjected γ-HCH to mechanochemical (MC) treatment with a planetary ball mill in the presence of CaO to investigate the feasibility of using this method for the treatment of γ-HCH stockpiles. We confirmed the degradation of γ-HCH and investigated the degradation mechanism. The major intermediates were identified to be 1,3,4,5,6-pentachlorocyclohexene (γ-PCCH) and chlorobenzenes (CBzs). Analysis of the steric structure of γ-HCH and identification of the degradation intermediates suggested that successive dehydrochlorination led to the formation of trichlorobenzenes. Products of further degradation (dichlorobenzenes, monochlorobenzene, and benzene) were also detected. Surprisingly, methane and ethane were also detected, which suggests cleavage of the C-C bonds of the cyclohexane ring and hydrogenation. All of the chlorine atoms in the γ-HCH could be transformed into inorganic chloride compounds by the MC treatment with CaO. Our results indicate that γ-HCH can be completely dechlorinated by MC treatment.
authors: Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan. nomura-yuugo@jqa.jp
authors: Yugo
authors: Y
authors: Nomura
authors: Kazuo
authors: K
authors: Fujiwara
authors: Akihiko
authors: A
authors: Terada
authors: Satoshi
authors: S
authors: Nakai
authors: Masaaki
authors: M
authors: Hosomi
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D001556:Hexachlorocyclohexane / Q000032:analysis / Q000737:chemistry*; D007306:Insecticides / Q000737:chemistry*; D055595:Mechanical Phenomena; D010087:Oxides / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D004785:Environmental Pollutants; D007306:Insecticides; D010087:Oxides; D001556:Hexachlorocyclohexane; C016538:lime