title: The effect of oxygen on chemical dechlorination of dieldrin using iron sulphides.
abstract: The degradation of dieldrin by ferric sulphide (FeS(2)) in aqueous solution was investigated when shielded against sunlight. An oxidative dechlorination process was observed under aerobic and anaerobic conditions; oxygen volume changed the degradation rate of dieldrin and the generation rate of reaction products. The dechlorination rate under microaerophilic conditions was fastest among the anaerobic to air oxygen concentrations. For this experiment, over 99% of the dieldrin was degraded, and 90% of the released chloride was detected after 30 d under 10 μ mol oxygen. The major reaction products were different depending on the dose of oxygen. In the case of aerobic conditions, low molecular weight organic acids, such as formic acid, lactic acid, and oxalic acid, were generated as major reaction products. However, under anaerobic conditions, C(16)H(22)O(4) (dibutyl phthalate) and C(6)H(13)ClO (3-chloro-4-methyl-2-pentanol) were detected as reaction intermediates, and small amounts of succinic acid, malonic acid, and formic acid were also generated. These reactions proceed by FeS(2) interface reactions with H(2)O under anaerobic condition, or O(2) under aerobic condition.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Institute for Geo-Resources and Environment, Onogawa 16-1, Tsukuba-shi, Ibaraki 305-0053, Japan. j.hara@aist.go.jp
authors.forename: Junko
authors.initials: J
authors.lastname: Hara
mesh_terms: D002713:Chlorine / Q000737:chemistry*; D004026:Dieldrin / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods; D054879:Halogenation; D007306:Insecticides / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*
chemical_list: D007306:Insecticides; D013440:Sulfides; C011342:pyrite; D002713:Chlorine; D007501:Iron; D004026:Dieldrin; D010100:Oxygen