Role of secondary minerals in the acid generating potential of weathered mine tailings: Crystal-chemistry characterization and closed mine site management involvement.

Mine tailings exposed to water and oxygen generate acid mine drainage (AMD) when the neutralizing minerals are insufficient to buffer the acid produced by sulfide oxidation. Mineral reactivity, such as sulfide oxidation and carbonate dissolution, leads to several changes within mine tailings in terms of their physical, mineralogical, and geochemical properties, which may lead to the release of metal(oid)s (e.g.

As(V) and As(III) sequestration by starch functionalized magnetite nanoparticles: influence of the synthesis route onto the trapping efficiency.

We report the effect of the synthesis route of starch-functionalized magnetite nanoparticles (NPs) on their adsorption properties of As(V) and As(III) from aqueous solutions. NP synthesis was achieved by two different routes implying the alkaline precipitation of either a mixed Fe/Fe salt solution (MC samples) or a Fe salt solution in oxidative conditions (MOP samples). Syntheses were carried out with starch to Fe mass ratio (R) ranging from 0 to 10.

Stability of magnetic LDH composites used for phosphate recovery.

Layered double hydroxides (LDH) and their magnetic composites have been intensively investigated as recyclable high-capacity phosphate sorbents but with little attention to their stability as function of pH and phosphate concentration. The stability of a FeO@SiO-MgFe LDH P sorbent as function of pH (5-11) and orthophosphate (P) concentration (1-300 mg P/L) was investigated. The composite has high adsorption capacity (approx.

Nitrite reduction by biogenic hydroxycarbonate green rusts: evidence for hydroxy-nitrite green rust formation as an intermediate reaction product.

The present study investigates for the first time the reduction of nitrite by biogenic hydroxycarbonate green rusts, bio-GR(CO3), produced from the bioreduction of ferric oxyhydroxycarbonate (Fohc), a poorly crystalline solid phase, and of lepidocrocite, a well-crystallized Fe(III)-oxyhydroxide mineral. Results show a fast Fe(II) production from Fohc, which leads to the precipitation of bio-GR(CO3) particles that were roughly 2-fold smaller (2.3 ± 0.

Reductive transformation and mineralization of an azo dye by hydroxysulphate green rust preceding oxidation using H(2)O(2) at neutral pH.

In this study, the reactivity of hydroxysulphate green rust (GR(SO(4)(2-))) toward reductive transformation, oxidative degradation and mineralization of organic compounds was evaluated using Methyl Red (MR) as model pollutant. The GR(SO(4)(2-)) was synthesized by co-precipitation method and characterized by X-ray diffraction (XRD), Mössbauer spectroscopy and Fourier Transform Infrared (FTIR) analyses. Reductive decolourization of MR solution occurred in the presence of GR(SO(4)(2-)), while no total organic carbon (TOC) decay was observed during the equilibration time.

Iron(II,III) hydroxycarbonate green rust formation and stabilization from lepidocrocite bioreduction.

Bioreduction of the well-crystallized ferric oxyhydroxide gamma-FeOOH lepidocrocite was investigated in batch cultures using Shewanella putrefaciens bacterium (strain CIP 8040) at initial pH 7.5 in bicarbonate buffer. The cultures were performed with formate as electron donor without phosphate, in the presence or absence of anthraquinone-2,6-disulfonate (AQDS) as electron shuttle.