Decontamination of TCE- and U-rich waters by granular iron: Role of sorbed Fe(II)

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Journal of Environmental Engineering

DOI:https://doi.org/10.1061/(ASCE)0733-9372(1998)124:1(25)· OSTI ID:577362

Charlet, L; Liger, E ^[1]; Gerasimo, P ^[2]

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1. Univ. of Grenoble-I (France)
2. Service de Protection Radiologique des Armees, Clamart (France)

Uranium (UO{sub 2}{sup 2+}) and chlorinated aliphatics [tetrachloroethane (PCE) and trichloroethane (TCE)] can be reduced and thus immobilized or degraded, respectively, by the same abiotic mechanism. In this mechanism the reduction reaction is coupled to the oxidation of Fe(II) sorbed on iron corrosion products such as hematite. This is indicated by the equilibrium E{sub h} values measured during uranium immobilization and PCE degradation reactions of zerovalent iron. These values fit closely with those measured in the Fe(II)-{alpha}Fe{sub 2}O{sub 3}-H{sub 2}O system (in the absence of U or PCE), not those of the Fe(o)/Fe(II) or H{sub 2}(g)/H{sub 2}O couples. Because iron (II) is very unstable in environments that are not strictly anaerobic, Fe(o) serves as a source of Fe(II). The reduction kinetic rate, analyzed in detail for the reduction of U(VI), is found to be a function of the concentration of OH{sup {minus}}, Fe{sup 2+} and reactive surface sites, and is given in terms of sorbed species concentrations by {l_brace}d[U(VI)]{sub ads}{r_brace}/dt = {l_brace}{minus}k{prime}[{triple_bond}FeOFeOH{sup 0}][U(VI)]{sub ads}{r_brace}. This rate law applies to organic pollutants as well, as long as they can be reduced by surface Fe(II): {l_brace}d[Pollutant]{r_brace}/dt = {l_brace}{minus}k{prime}[{triple_bond}FeOFeOH{sup 0}][Pollutant]{r_brace}. This mechanism suggests new possibilities for the improvement of low-cost decontamination techniques for U- and chlorinated aliphatic-rich waters.

• Sponsoring Organization: USDOE
• OSTI ID: 577362
• Journal Information: Journal of Environmental Engineering, Journal Name: Journal of Environmental Engineering Journal Issue: 1 Vol. 124; ISSN 0733-9372; ISSN JOEEDU
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
CHLORINATED ALIPHATIC HYDROCARBONS
GROUND WATER
IRON
REDUCTION
REMEDIAL ACTION
URANIUM
WATER CHEMISTRY
WATER POLLUTION