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 FriedelÂs
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.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3861 |
| Date | 16 August 2006 |
| Creators | Ko, Sae Bom |
| Contributors | Batchelor, Bill |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 3769570 bytes, electronic, application/pdf, born digital |
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