Liquid phase hydrodechlorination of dieldrin and DDT over Pd/C and Raney-Ni

Abstract

Selectivity and product distribution of hydrodechlorination (HDCl) of dieldrin and DDT are studied in different liquid phase systems, namely in: (1) in ethanol; and (2) in the supported ionic liquid heterogeneous catalytic system (multiphase system), composed by the organic phase and aqueous KOH, a quaternary ammonium ionic liquid promoter (Aliquat 336), and a metal catalyst, e.g. 5% Pd/C, 5% Pt/C, or RaneyNi. At 50 8C and atmospheric pressure of hydrogen, a quantitative hydrodechlorination of DDT in the biphasic system with ionic liquid layer is achieved in 40 min and in 4 h with Raney-Ni and Pd/C, respectively, while the reaction on Pt/C or on Pd/C without Aliquat 336 is slow. Dieldrin undergoes partial dechlorination, with high selectivity achievable only for its mono-and bi-dechlorination products. Dechlorination pathways and reactivity of different types of organic chlorine atoms versus the catalyst nature and other conditions are discussed. #

Effects of nano-sized zero-valent iron (nZVI) on DDT degradation in soil and its toxicity to collembola and ostracods

“…Several techniques or approaches have been developed for remediation of DDT, including 73 biodegradation treatments , soil excavation and incineration or thermal degradation 74 at high temperatures (Rodante et al, 1992), washing soil with surfactants (Smith et al, 2004), and 75 advanced oxidation technologies, such as photochemical reactions using nano-sized TiO2/UV (Lin 76 and Lin, 2007) and metal-catalyzed reactions (Pd/C catalysts) (Zinovyev et al, 2005). Both the 77 latter have been shown to be effective for DDT degradation, but they are also expensive treatment 78 methods.…”

Multiphasic Heterogeneous Catalysis Mediated by Catalyst‐Philic Liquid Phases

“…It produced a mixture of products derived from the subsequent removal of chlorines, up to a small percentage of mono-chlorinated derivative. 94 DDT [1,19-bis-(4-chlorophenyl)-2,2,2-trichloroethane] could be hydrodechlorintated completely both with Pd/C and RaneyNi, provided that A336 was present. The aliphatic chlorines reacted faster than the aromatic ones, the first via base promoted elimination of HCl.…”

“…The aliphatic chlorines reacted faster than the aromatic ones, the first via base promoted elimination of HCl. 94 Finally, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T: agent orange) and pentachlorophenol (PCP)-two acidic polychlorinated pesticides-were also investigated. In these cases the presence of A336 contributed to the solubility of the reagent in the organic phase, by forming the ion pair between the anion of the reagent and the ammonium cation.…”

Chemical Degradation of Chlorinated Organic Pollutants for In Situ Remediation and Evaluation of Natural Attenuation

“…Dieldrin has a higher persistence than TCE and is less amenable to reductive dechlorination under anaerobic conditions. Remediation techniques for dieldrin (UV/Fenton reagent, UV/chemical reaction, Pd/C catalyst, solar photocatalysis, and bioremediation) have been reported (Books, 1980;Maule et al, 1987;Bandala et al, 2002;Kusvuran and Erbatur, 2004;Chiu et al, 2005;Zinovyev et al, 2005;Dureja et al, 1987;Baczynski et al, 2004), but dieldrin transforms to mono-or di-dechlorinated intermediates still having a bicyclic ring structure. A study of the use of Fenton reagent for aldrin reports the transformation from aldrin to oxalic acid, acetic acid, chlorohexanone, cyclohexanol, cis-2-hydroxy-cyclohexanone, cis-2-methyl-cyclohexanol, 4-hydroxycyclohexanone, cis-4-methylcyclohexanol, 1-cyclopropyl-1-hydroxyethylene, and trans-dihydroxycyclohexane (Kusvuran and Erbatur, 2004).…”