Fe(II) coordination transition regulates reductive dechlorination: The overlooked abiotic role of lactate.
Water Res
; 254: 121342, 2024 May 01.
Article
in En
| MEDLINE
| ID: mdl-38428238
ABSTRACT
The coordination environment of Fe(II) significantly affect the reductive reactivity of Fe(II). Lactate is a common substrate for enhancing microbial dechlorination, but its effect on abiotic Fe(II)-driven reductive dechlorination is largely ignored. In this study, the structure-reactivity relationship of Fe(II) is investigated by regulating the ratio of lactateFe(II). This work shows that lactate-Fe(II) complexing enhances the abiotic Fe(II)-driven reductive dechlorination with the optimum lactateFe(II) ratio of 1020. The formed hydrogen bond (Fe-OHââââââO = C-) and Fe-O-C metal-ligand bond result in a reduced Fe(II) coordination number from six to four, which lead to the transition of Fe(II) coordination geometry from octahedron to tetrahedron/square planar. Coordinatively unsaturated Fe(II) results in the highest reductive dechlorination reactivity towards carbon tetrachloride (k1 = 0.26254 min-1). Excessive lactate concentration (> 10 mM) leads to an increased Fe(II) coordination number from four to six with a decreased reductive reactivity. Electrochemical characterization and XPS results show that lactate-Fe(II)-I (C3H5O3-Fe(II) = 1020) has the highest electron-donating capacity. This study reveals the abiotic effect of lactate on reductive dechlorination in a subsurface-reducing environment where Fe(II) is usually abundant.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Lactic Acid
/
Metals
Language:
En
Journal:
Water Res
Year:
2024
Document type:
Article