Chemical dechlorination of polychlorinated biphenyls (PCBs) from dielectric oils

Abstract

We studied the chemical dechlorination of the polychlorinated biphenyls (PCBs) in some dielectric oils via nucleophilic substitution of the chloro atoms by polyethylene alkoxide. The influence of temperature, ultrasounds, polyethylene glycol (PEG) and base type was investigated. Our findings show that dechlorination of PCBs by chemical treatment is effective at moderate temperature (90-100 • C) and is strongly dependent on the nature of matrix oil. Stirring affects the process yield by influencing the homogeneity of the oil/glycol two-phase system. Ultrasounds can improve the process efficiency by making operating conditions less severe.

Avaliação Dos Resíduos Gerados Durante a Destruição De PCBS Pelo Processo Catalisado Por Base

“…2,3,6 No setor elétrico além do montante de PCBs retiradas dos equipamentos atendendo à Convenção, ainda ocorreu a contaminação de óleo mineral isolante (OMI) utilizado para a substituição do Ascarel ® nos transformadores de forma inadequada, como, por exemplo, o simples esgotamento do mesmo e enchimento do equipamento com óleo mineral, havendo ainda PCBs impregnadas no papel isolante do transformador. [8][9][10] Diante desse cenário, diversos métodos de tratamento para descontaminação de matrizes com PCBs foram criados. [11][12][13][14] Dentre estes, os processos de descloração catalisados por base são tratamentos químicos com menor impacto ambiental que podem gerar a matriz descontaminada (oléo mineral isolante), a lama reacional e gases de exaustão.…”

Reductive dechlorination of chlorobenzene in supercritical water catalyzed by Fe/ZrO2

“…A number of studies have investigated degradation of organochlorine compounds via dechlorination to transform chlorinated organics into their non-chlorinated analogues (Cafissi et al 2007;Schrick et al 2002). In recent years, reactions in subcritical or supercritical water have been recognized as an innovative and environmentally benign approach for the degradation of organic pollutants, where subcritical water is defined as hot water with sufficient pressure to maintain the liquid state and supercritical water is defined as water at temperatures and pressures higher than the critical point (374°C, 22.1 MPa).…”

Effective Elimination of PCBs Catalyzed by the Palladium/Hydrazine System as an Ecological Sustainable Process

“…The most widely accepted method for the destruction of the PCBs consists of incineration at elevated temperatures, although this is expensive and may produce undesirable and very toxic byproducts such as polychlorinated dibenzofurans and polychlorinated dibenzodioxins…”