Chromate removal from aqueous wastes by reduction with ferrous ion

Eary, L. E.; Rai, Dhanpat

doi:10.1021/es00173a018

Cited by 597 publications

(446 citation statements)

References 12 publications

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“…2d). Although positive charges on variable charge surfaces can explain maximum Cr(VI) sorption when pH < 3, the fact that the pyritic material showed high sorption even when the pH value was increased could be related to its abundant oxy-hydroxides content, some of them with elevated point of zero charge (Bradl, 2004), as well as related to Cr(VI) reduction to Cr(III) in the presence of S 2− and Fe 2+ , given that Cr(III) may be precipitated at pH values between 6 and 11 (Eary and Rai, 1988;Sass and Rai, 1987;Weng et al, 1994). Mussel shell amendment did not cause great changes in the sorbent behavior of the amended materials (Fig.…”

Section: Sorptionmentioning

confidence: 99%

Cr(VI) sorption/desorption on untreated and mussel-shell-treated soil materials: fractionation and effects of pH and chromium concentration

et al. 2015

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Abstract. We used batch-type experiments to study Cr(VI) sorption/desorption on granitic material, forest soil, pyritic material, mussel shell, and on forest soil and granitic material amended with 12 t ha −1 (1.2 kg m −2 ) shell, considering the effects of varying Cr(VI) concentration and pH. Sequential extractions were carried out to fractionate adsorbed Cr(VI) and to determine the stability of Cr(VI) retention. The pyritic material had the highest Cr(VI) retention capacity, whereas the granitic material showed the lowest retention potential. When high Cr concentrations were added, some saturation of the adsorbent surfaces became apparent, but Cr release remained low. The highest Cr retention was achieved at a very acid pH value, with release progressively increasing as a function of increasing pH. The amendment with 12 t ha −1 mussel shell did not cause marked changes in Cr(VI) retention. Sorption data were satisfactory adjusted to the Freundlich model. Regarding Cr(VI) fractionation, the soluble fraction (weakly bound) was dominant in mussel shell and in the unamended and amended granitic material, whereas more stable fractions dominated in the pyritic material (residual fraction) and in the forest soil (oxidizable fraction). In conclusion, the pyritic material presented the highest Cr(VI) retention capacity, while the retention was low and weak on the granitic material; mussel shell was not characterized by a marked Cr(VI) retention potential, and it did not cause remarkable increase in Cr(VI) retention when used to amend the granitic material or the forest soil.

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Section: Sorptionmentioning

confidence: 99%

Cr(VI) sorption/desorption on untreated and mussel-shell-treated soil materials: fractionation and effects of pH and chromium concentration

et al. 2015

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“…Experimental evidence indicates that the oxygenation of Fe(I1) in solutions (pH >5) is generally found to be first order with respect to Fe(I1) and 0 2 concentration and second-order with respect to OH-. The rate of oxidation of Fe(I1) in solution by oxygen at pH 8 is a few minutes (Eary and Rai 1988;Buerge and Hug 1997). In contrast, the oxidation rate (as a half-life) observed in natural sediments (surface Fe[II] thought to be adsorbed Few] and Few]C03) was found to be 0.3 to 1.1 hr.…”

Section: A2 Sediment Oxidation Mechanismsmentioning

confidence: 96%

In Situ Redox Manipulation Proof-of-Principle Test at the Fort Lewis Logistics Center: Final Report

Vermeul¹,

Williams²,

Evans³

et al. 2000

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“…As(V), arsenate, is reduced to As(III), arsenite, which is very mobile and has led to elevated groundwater concentrations on many occasions. Chromium(VI) can be reduced to Cr (III) by reactions with e.g., Fe (acting as a catalyst (Eary and Rai 1988)) and organic matter (Kozuh et al 2000). The direct relation between DOM and reduction rates of chromium was discussed by Buerge and Hug (1998), and Francis and Dodge (1990) showed that Cr was liberated by Fe-oxyhydroxides by-again-microbial action.…”

Section: Heavy Metal Response To Reductionmentioning

confidence: 99%

Delayed immobilization of heavy metals in soils and sediments under reducing and anaerobic conditions; consequences for flooding and storage

Vink

Harmsen²,

Rijnaarts

2010

J Soils Sediments

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Purpose The consequences of permanent inundation and storage of flood plain soils and aquatic sediments on metal mobility were studied. The main goal was to quantify kinetic mobilisation processes in order to pinpoint the conditions that pose emission risks to groundwater and surface waters. Materials and methods Anaerobic pore water compositions of six existing depots, containing sediments from either aquatic or terrestrial origin, were measured to obtain reliable field references. Reduction experiments were performed with SOFIE cells, in which time-dynamic measurements of reducing pore waters were carried out at the reigning redox conditions. A parallel experiment tested the possibility if sulfide-deficiencies could be compensated by the reduction of added gypsum, thus increasing the available pool of reactive S. Model calculations were performed to distinguish between the thermodynamic and kinetic processes. Results and discussion Reduction of flood plain soils showed that dissolved organic matter (DOM) concentrations increased up to 7-fold over time, as a result of nutrient-mediated metabolic boost of organic matter degrading microorganisms. The association of metals to DOM increased significantly due to the loss of reactive Mn-oxide and Fe-oxyhydroxide sorption phases during reduction. DOM released metals only slowly, therefore kinetically hindering the phase shifting to stable metalsulfide precipitates. The observed effects lasted at least 10 months. In aquatic sediments, reduction rates of sulphates were six times faster, and the release of DOM occurred in lower amounts than in soils from terrestrial origin. It is shown that the addition of gypsum stimulates the formation of sulfides, thereby decreasing dissolved concentrations of most metals. On the short term however, the addition of gypsum leads to elevated concentrations of Zn and Cd due to increased electrolyte strength and subsequent Ca-metal-competition for sorption sites. This effect may be eliminated by not only adding an electron acceptor to the sediment, but also an effective donor, e.g., degradable organic matter. Conclusions For depots containing flood plain soils, the same kinetic mechanisms were observed as in the reduction experiments (elevated production of DOM and associated metals). It was concluded that reduction of flood plain soils may not necessarily result in efficient metal trapping. When storage is considered, a distinction should be made between sediments of terrestrial and aquatic origin.

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Chromate removal from aqueous wastes by reduction with ferrous ion

Cited by 597 publications

References 12 publications

Cr(VI) sorption/desorption on untreated and mussel-shell-treated soil materials: fractionation and effects of pH and chromium concentration

Cr(VI) sorption/desorption on untreated and mussel-shell-treated soil materials: fractionation and effects of pH and chromium concentration

In Situ Redox Manipulation Proof-of-Principle Test at the Fort Lewis Logistics Center: Final Report

Delayed immobilization of heavy metals in soils and sediments under reducing and anaerobic conditions; consequences for flooding and storage

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