Identification of active agents for tetrachloroethylene degradation in Portland cement slurry containing ferrous iron

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Title: Identification of active agents for tetrachloroethylene degradation in Portland cement slurry containing ferrous iron
Author: Ko, Sae Bom
Abstract: Fe (II ) -based degradative solidification /stabilization (Fe (II ) -DS /S ) technology is the modification of conventional solidification /stabilization (S /S ) . Inorganic pollutants are immobilized by Fe (II ) -DS /S while organic pollutants are destroyed . Experimental studies were conducted to identify the active agents for Tetrachloroethylene (PCE ) degradation as well as the conditions that enhance the formation of the active agents in the Fe (II ) -DS /S system . PCE was chosen as a model chlorinated aliphatic hydrocarbon in this study . First , the conditions that lead to maximizing production of the active agents were identified by measuring the ability of various chemical mixtures to degrade PCE . Results showed that Fe (II ) , Fe (III ) , Ca , and Cl were the the important elements that affect degradation activity . Elemental compositions of the mixtures and the conditions affecting solid formation might be the important factors in determining how active solids are formed . Second , instrumental analyses (XRD , SEM , SEM -EDS ) were used to identify minerals in chemical mixtures that have high activities . Results indicate that active agents for PCE degradation in Portland cement slurries and in cement extracts might be one of several AFm phases . However , systems without cement did not form the same solids as those with cement or cement extract . Ferrous hydroxide was identified as a major solid phase formed in systems without cement . Finally , the effect of using different types of ordinary Portland cement (OPC ) on PCE degradation rate during Fe (II ) -DS /S was examined and the solids were examined by instrumental analyses (XRD , SEM , SEM -EDS ) . Four different OPC (Txi , Lehigh , Quikrete , and Capitol ) showed different PCE degradation behaviors . Pseudo first -order kinetics was observed for Capitol and Txi OPC and second -order kinetics was observed for Quikrete . In the case of Lehigh cement , pseudo first -order kinetics was observed in cement slurry and second -order kinetics in cement extract . Calcium aluminum hydroxide hydrates dominated solids made with Txi , Quikrete , and Lehigh cements and Friedel ? ?s salt was the major phase found in solids made with Capitol cements . Fe tended to be associated with hexagonal thin plate particles , which were supposed to be a LDH .
URI: http : / /hdl .handle .net /1969 .1 /3861
Date: 2006-08-16

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Identification of active agents for tetrachloroethylene degradation in Portland cement slurry containing ferrous iron. Available electronically from http : / /hdl .handle .net /1969 .1 /3861 .

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