Previously, the concept of reactive activated carbon (RAC), where the porous structure of activated carbon (AC) is impregnated with palladized zerovalent iron, has been proposed to be effective to adsorb and dechlorinate polychlorinated biphenyls (PCBs). To explain the low dechlorination of PCBs bound to actual aquatic sediments under remediation with RAC, this study investigated the role of various solid organic and inorganic sediment components in adsorbing and desorbing PCBs. Detailed fate and transport mechanism of 2-chlorinated biphenyl (2-CIBP) spiked to sediment components, including kaolin, montmorillonite (MMT), coal, graphite, AC, and their mixture, was revealed. Adsorption and holding capability of sediment components toward 2-CIBP strongly influenced amount of spiked 2-CIBP, amount of desorbed 2-CIBP, overall dechlorination of 2-CIBP to biphenyl (BP), and eventual partitioning of 2-CIBP and BP to water, sediment component, and RAC. Order of the amount of spiked 2-CIBP to sediment components after drying, following AC> mixture > coal > graphite > kaolin > MMT, was in agreements (in opposite direction) with order of the amount of desorbed 2-CIBP and order of overall 2-CIBP dechlorination. Substantial role of organic components in aquatic sediments for holding 2-CIBP and thus preventing it from dechlorination on RAC was proven. (C) 2017 Elsevier B.V. All rights reserved.