In Situ Reduction of Hexavalent Chromium in Alkaline Soils Enriched with Chromite Ore Processing Residue

Higgins, Thomas E.; Halloran, Amy R.; Dobbins, Maribeth E.; Pittignano, Alex J.

doi:10.1080/10473289.1998.10463768

Cited by 56 publications

(29 citation statements)

References 5 publications

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“…Several researches have demonstrated that adding organic reductants to soils could enhance Cr(VI) reduction (Bajt et al, 1993;Bolan et al, 2003;Higgins et al, 1998;Losi et al, 1994;Tokunaga et al, 2003). In this study, the DOW-EX M4195 resin extraction method was used to study the effect of two compost amendments on the Cr(VI) bioavailability in three different soils spiked with various levels of Cr(VI).…”

Section: Introductionmentioning

confidence: 99%

Using the Selective Ion Exchange Resin Extraction and XANES Methods to Evaluate the Effect of Compost Amendments on Soil Chromium(VI) Phytotoxicity

et al. 2006

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The Cu-saturated selective ion exchange resin (DOWEX M4195) extraction method was used to investigate the effects of two amendments, 5 and 15% organic matter in the form of hog-dung compost (HC) or cattledung compost (CC), on Cr(VI) bioavailability in three soils spiked with various levels of Cr(VI). The results showed that addition of composts could decrease the amounts of resin-extractable Cr(VI) in Cr(VI)-spiked soils, and the CC amendment decreased resin-extractable Cr(VI) more than the HC amendment. The X-ray Absorption Near-edge Structure spectroscopy (XANES) method was used to examine the distribution of Cr(III) and Cr(VI) species in Cr(VI)-spiked soils that were affected by compost amendments, and to elucidate the mechanisms for the decrease of resin-extractable Cr(VI) due to the application of composts. The XANES results suggested that the decrease in the amounts of resin-extractable Cr(VI) after compost addition was mainly due to the reduction of Cr(VI) to Cr(III). The amounts of soil resin-extractable Cr(VI) were also correlated with wheat seedling growth in order to evaluate the effect of compost amendments on decreasing the phytotoxicity of soil Cr(VI). The results showed that there was a sigmoidal relationship between soil resin-extractable Cr(VI) and the plant height of wheat seedlings and the obtained effective concentrations of resin-extractable Cr(VI) resulting in 10 and 50% growth inhibition (EC 10 and EC 50 ) were 76 and 191 mg kg )1 respectively. The above results suggested that the resin extraction method was a useful tool for assessing Cr(VI) phytotoxicity and that addition of composts would enhance Cr(VI) reduction to Cr(III) in soils and thus relieve Cr(VI) phytotoxicity.

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Section: Introductionmentioning

confidence: 99%

Using the Selective Ion Exchange Resin Extraction and XANES Methods to Evaluate the Effect of Compost Amendments on Soil Chromium(VI) Phytotoxicity

et al. 2006

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“…7 Water in contact with high-lime COPR has a characteristically high pH of 11.5-12, 6 and can contain up to 1.6 mmol.L -1 Cr(VI) as chromate 8 . Until recently COPR has been used as a fill material for roads and other construction projects, 4,6,9 or was dumped in unlined tips [10][11][12][13] . As a result there are numerous sites around the world where water from COPR is contaminating the surrounding area with Cr(VI), which is a major concern as Cr(VI) is carcinogenic, mutagenic and toxic.…”

Section: Introductionmentioning

confidence: 99%

Chromate Reduction in Highly Alkaline Groundwater by Zerovalent Iron: Implications for Its Use in a Permeable Reactive Barrier

Fuller

Stewart

Burke

2013

Ind. Eng. Chem. Res.

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It is not currently known if the widely used reaction of zero valent iron (ZVI) and Cr(VI) can be used in a permeable reactive barrier (PRB) to immobilise Cr leaching from hyper alkaline chromite ore processing residue (COPR). This study compares Cr(VI) removal from COPR leachate and chromate solution by ZVI at high pH. Cr(VI) removal occurs more rapidly from the chromate solution than from COPR leachate. The reaction is first order with respect to both [Cr(VI)] and the iron surface area, but iron surface reactivity is lost to the reaction.Buffering pH downwards produces little change in the removal rate or the specific capacity of iron until acidic conditions are reached. SEM and XPS analysis confirm that reaction products accumulate on the iron surface in both liquors, but that other surface precipitates also form in COPR leachate. Leachate from highly alkaline COPR contains Ca, Si and Al that precipitate on the iron surface and significantly reduce the specific capacity of iron to reduce Cr(VI). This study suggests that although Cr (VI) reduction by ZVI will occur at hyper alkaline pH, other solutes present in COPR leachate will limit the design life of a PRB. 4

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“…Cr(VI) is highly mobile, severely toxic at moderate doses, and classified as a respiratory carcinogen in humans. In contrast, Cr(III) is used as a dietary element at low doses, and in most environmental systems is immobile (Higgins et al, 1998). The COPR, which contains both Cr(III) and Cr(VI), was discovered not as benign as initially thought; yellow chromate solutions are often observed to leach from locations where COPR is deposited and elevated Cr(VI) concentrations are measured in ground water and water bodies in the proximity of these sites (Geelhoed et al, 2002).…”

Section: Introductionmentioning

confidence: 93%

Impact of brownmillerite hydration on Cr(VI) sequestration in chromite ore processing residue

Moon

Wazne

2011

Geosci J

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Experimental and modeling studies were conducted to delineate the reaction progress of chromite ore processing residue (COPR) upon hydration and the roles of brownmillerite and calcium aluminum chromium oxide hydrates (CAC) in the scavenging of hexavalent chromium. A kinetic study was conducted by preparing slurry samples with both synthetic brownmillerite and actual COPR samples at ambient temperatures. The hydration reaction of brownmillerite using synthetic brownmillerite was very fast (within 1 hour) and was completed within 2 days. However, the hydration of brownmillerite embedded in COPR to its hydration byproducts was not clearly observed after 7 days of aging. Newly formed Ca 4 Al 2 O 6 (CrO 4 )·14H 2 O (CAC-14) was observed after 1 hour of aging in both samples. However, the rate of formation of CAC-14 with synthetic brownmillerite was much faster than the COPR embedded brownmillerite. The reaction progress of synthetic brownmillerite and COPR upon chromate influx was simulated by a reaction path modeling program. The phase transformation of both samples can be predicted by the constructed model. Moreover, the formation of CACs upon chromate addition was predicted by the model, suggesting an effective sink for Cr(VI).

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In Situ Reduction of Hexavalent Chromium in Alkaline Soils Enriched with Chromite Ore Processing Residue

Cited by 56 publications

References 5 publications

Using the Selective Ion Exchange Resin Extraction and XANES Methods to Evaluate the Effect of Compost Amendments on Soil Chromium(VI) Phytotoxicity

Using the Selective Ion Exchange Resin Extraction and XANES Methods to Evaluate the Effect of Compost Amendments on Soil Chromium(VI) Phytotoxicity

Chromate Reduction in Highly Alkaline Groundwater by Zerovalent Iron: Implications for Its Use in a Permeable Reactive Barrier

Impact of brownmillerite hydration on Cr(VI) sequestration in chromite ore processing residue

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