2,3,7,8-Tetrachloro dibenzo- p-dioxin can be successfully decomposed over 2:1 dioctahedral smectite—a reactivity index study

Abstract

2:1 Dioctahedral smectite family has shown its capability to decompose 2,3,7,8-tetrachloro dibenzo- p-dioxin (TeCDD) using the active hydroxyl hydrogen attached with the central octahedral aluminum, as monitored using density functional theory (DFT). From the values of the local softness and the charge on the hydrogen atom of the bridging/structural (occurring on the surface) hydroxyl attached to octahedral/tetrahedral metal site present in smectite used as a first approximation to the local hardness, it is concluded that the local acidities of the inorganic material systems are dependent on several characteristics which are of importance within the framework of hard–soft acid–base (HSAB) principle. The first step in this process of decomposition is the abstraction of chlorine bound to TeCDD using surface hydrogen of smectites. This results in non-chlorinated dibenzo- p-dioxin (NCDD), which is less toxic than TeCDD. The second step is the formation of a dative bond between oxygen of NCDD and hydroxyl proton of smectite, with the breaking of CO bond of NCDD. The reaction mechanism is postulated within the helm of DFT using Fukui functions for all possible chlorinated and non-chlorinated dioxin varieties along with clay clusters. The material is identified to act for the decomposition of dioxin.