title: Pseudo-first-order reaction of chemically and biologically formed green rusts with HgII and C₁₅H₁₅N₃O₂: effects of pH and stabilizing agents (phosphate, silicate, polyacrylic acid, and bacterial cells).
abstract: The kinetics of Hg(II) and methyl red (MR) reduction by hydroxycarbonate green rust (GR1) and by hydroxysulfate green rust (GR2) were studied in the presence of naturally occurring organic and inorganic ligands (phosphate, polyacrylic acid, bacterial cells, silicate). The reducing ability of biogenic hydroxycarbonate green rust (GR1bio), obtained after microbial reduction of lepidocrocite by Shewanella putrefaciens, was also investigated and compared to those of chemically synthesized GR1 and GR2 (GR1ab and GR2ab). Pseudo first-order rate constants (kobs) of Hg(II) reduction (at pH 7.0, 8.2, and 9.5) and MR reduction (at pH 7.0) were determined and were normalized to the structural Fe(II) content of GRs (kFeII) and to the estimated concentration of surface Fe(II) sites (kS). The kS values ranged from 0.3 L mmol(-1) min(-1) to 43 L mmol(-1) min(-1) for the Hg reduction, and from 0.007 L mmol(-1) min(-1) to 3.4 L mmol(-1) min(-1) for the MR reduction. No significant discrepancy between GRab and GRbio was observed in term of reactivity. However, the reduction kinetics of MR was generally slower than the Hg(II) reduction kinetics for all tested GRs. While a slight difference in Hg(II) reduction rate was noted whatever the pH values (7.0, 8.2, or 9.5), the reduction of MR was significantly affected in the presence of ligands. A decrease by a factor of 2-200, depending on the type of ligand used, was observed. These data give new insights into the reactivity of GRs in the presence of co-occurring organic and inorganic ligands, and have major implications in the characterization of contaminated systems as well as water treatment processes.
authors.affiliation: Université de Lorraine, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France; CNRS, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France.
authors.forename: P-Ph
authors.initials: PP
authors.lastname: Remy
authors.affiliation: Université de Lorraine, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France; CNRS, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France.
authors.forename: M
authors.initials: M
authors.lastname: Etique
authors.affiliation: Université de Lorraine, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France; CNRS, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France.
authors.forename: A A
authors.initials: AA
authors.lastname: Hazotte
authors.affiliation: Université de Lorraine, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France; CNRS, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France.
authors.forename: A-S
authors.initials: AS
authors.lastname: Sergent
authors.affiliation: CNRS, CRPG, UMR 7358, BP 20, Vandœuvre-lès-Nancy F-54501, France; Université de Lorraine, CRPG, UMR 7358, BP 20, Vandœuvre-lès-Nancy F-54501, France.
authors.forename: N
authors.initials: N
authors.lastname: Estrade
authors.affiliation: CNRS, CRPG, UMR 7358, BP 20, Vandœuvre-lès-Nancy F-54501, France; Université de Lorraine, CRPG, UMR 7358, BP 20, Vandœuvre-lès-Nancy F-54501, France.
authors.forename: C
authors.initials: C
authors.lastname: Cloquet
authors.affiliation: ENSCR, CNRS, UMR 6226, CS 50837, Rennes Cedex 7 F-35708, France; Université européenne de Bretagne, Rennes F-35000, France.
authors.forename: K
authors.initials: K
authors.lastname: Hanna
authors.affiliation: Université de Lorraine, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France; CNRS, LCPME, UMR 7564, Institut Jean Barriol, Villers-lès-Nancy F-54601, France. Electronic address: frederic.jorand@univ-lorraine.fr.
authors.forename: F P A
authors.initials: FP
authors.lastname: Jorand
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D005079:Excipients / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry; D008628:Mercury / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D020614:Shewanella putrefaciens / Q000378:metabolism; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D001391:Azo Compounds; D005079:Excipients; D005290:Ferric Compounds; D005296:Ferrous Compounds; D006878:Hydroxides; D058085:Iron Compounds; D008903:Minerals; D010087:Oxides; D014874:Water Pollutants, Chemical; C517972:fougerite; C008492:methyl red; D008628:Mercury
keywords: Biogenic green rust; Cationic mercury; Layered double hydroxides; Methyl red; Reductive transformation; Surface area concentration