desired level of dechlorination. Currently, hydrogen can be an effective reductant of
COCs in the presence of supported metallic catalysts, such as palladium (Marques
et al. 1993; Schreier and Reinhard 1995; Lowry and Reinhard 1999; Zhang et al.
2013).
Concerning reduced sulfur species, they generally include S(-II) and S(III)
species, such as polysulfide ions S n
2À , hydrogen sulfide species HS
À and H 2 S
(Barbash and Reinhard 1989; Roberts et al. 1992), and sodium dithionite
Fig. 6.1 (a) Oxidation reduction potential (ORP) of iron and sulfur species and chlorinated
methanes, ethanes, and ethylenes at pH ¼ 7 and [Cl
À
] ¼ 10
À3 M [from Cwiertny and Scherer
(2010), adapted from Schwarzenbach et al. (2003)]. (b) Simplified Pourbaix diagram for Fe
0
-H 2 O
system under reference conditions (adapted from Matheson and Tratnyek (1994); 15
C, [Cl
À
] ¼
10
À3 M, Fe T ¼ 7.6 Â 10
À7 M)
300
R. Rodrigues et al.
COCs in the presence of supported metallic catalysts, such as palladium (Marques
et al. 1993; Schreier and Reinhard 1995; Lowry and Reinhard 1999; Zhang et al.
2013).
Concerning reduced sulfur species, they generally include S(-II) and S(III)
species, such as polysulfide ions S n
2À , hydrogen sulfide species HS
À and H 2 S
(Barbash and Reinhard 1989; Roberts et al. 1992), and sodium dithionite
Fig. 6.1 (a) Oxidation reduction potential (ORP) of iron and sulfur species and chlorinated
methanes, ethanes, and ethylenes at pH ¼ 7 and [Cl
À
] ¼ 10
À3 M [from Cwiertny and Scherer
(2010), adapted from Schwarzenbach et al. (2003)]. (b) Simplified Pourbaix diagram for Fe
0
-H 2 O
system under reference conditions (adapted from Matheson and Tratnyek (1994); 15
C, [Cl
À
] ¼
10
À3 M, Fe T ¼ 7.6 Â 10
À7 M)
300
R. Rodrigues et al.