In situ lead immobilization by apatite

Qu, Ying; Traina, Samuel J.; Logan, Terry J.; Ryan, James A.

doi:10.1021/es00046a007

Cited by 674 publications

(501 citation statements)

References 10 publications

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“…The NRMRL research program's initial goal was to demonstrate the feasibility of altering the mineralogy of lead in soil in a laboratory setting by using thermodynamic and kinetic studies. Orthophosphate (aqueous phosphorus, hydroxyapatite, or phosphate rock) rapidly and effectively precipitates lead from solution to form a series of lead phosphates of low aqueous solubilities (27,(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43). The final product of lead immobilization is primarily pyromorphite [Pb 5 (PO 4 ) 3 X, where X is OH, Cl, or F], which is stable under normal soil environmental conditions.…”

Section: Reducing Exposurementioning

confidence: 99%

Peer Reviewed: Reducing Children's Risk from Lead in Soil

Ryan¹,

Scheckel²,

Berti³

et al. 2004

Environ. Sci. Technol.

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Section: Reducing Exposurementioning

confidence: 99%

Peer Reviewed: Reducing Children's Risk from Lead in Soil

Ryan¹,

Scheckel²,

Berti³

et al. 2004

Environ. Sci. Technol.

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180

139

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“…The lead phosphate complexes form insoluble salts. This is illustrated by studies in which phosphate amendments have been used to reduce the solubility and mobility of lead in contaminated soil (Ma et al 1993). Furthermore, Zhang et al (1998;Zhang and Ryan 1999) determined rapid (within 60 min) and complete transformation of soil lead to the lead phosphate complex chloropyromorphite (Pb 5 (PO 4 ) 3 Cl[s]) in experiments mimicking gastric and intestinal pH values and in the presence of the phosphate mineral hydroxyapatite.…”

Section: Lead Phosphate Complexesmentioning

confidence: 99%

Lead Speciation in Artificial Human Digestive Fluid

Oomen

Tolls

Sips

et al. 2003

Archives of Environmental Contamination and Toxicology

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Abstract. For children, soil ingestion via hand-to-mouth behavior can be a main route of exposure to contaminants such as lead. The ingested lead can be mobilized from the soil and form new species during the digestion process. Speciation is known to affect the availability of metals for transport across biological membranes. In the present study, in vitro digestions were performed with (artificially contaminated) standard soil. Lead speciation was investigated in the artificial human intestinal fluid, i.e., chyme, to gain insight into the lead species and lead fractions that may be available for transport across the intestinal epithelium. To that end, both a lead ion selective electrode (Pb-ISE) and a voltammetric technique (differential pulse anodic stripping voltammetry, DPASV) were used. The results indicate that in chyme only a negligible lead fraction is present as free Pb 2ϩ , whereas lead phosphate and lead bile complexes are important fractions. The lead phosphate complexes appear to be voltammetrically labile, i.e., in dynamic equilibrium with Pb 2ϩ . Labile complexes can dissociate and the produced metal ions can subsequently be transported across the intestinal epithelium. Lead bile complexes may behave in a similar manner, or this organometal complex may be able to traverse the intestinal membrane. Therefore, substantially more than only the free metal ion should be considered available for transport across the intestinal epithelium.

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“…However, our results show direct evidence of dissolution-precipitation mechanism for both minerals. Such behaviour, that is dissolution of mineral and subsequent formation of new precipitate, was observed in reactions of synthetic HAP with lead (Ma et al 1993, Lower et al 1998, Manecki et al 2000a. Although XRD patterns did not reveal formation of new phases after reaction with cadmium, the SEM observations clearly show their occurence.…”

Section: Sem Analysesmentioning

confidence: 77%

“…Equilibria in water and soil solutions are mainly controlled by sorption/desorption and crystallization/dissolution processes. Therefore a promising way of eliminating mobile metals from soils is to convert them into stable metal phosphates by addition of soluble or insoluble phosphates (Levi Minzi & Petruzzelli 1984, Ma et al 1993, Ruby et al 1994, Xu & Schwartz 1994, Ma et al 1995, Cotter-Howells 1996, Lambert et al 1997, Zhang et al 1997, Fedoroff et al 1999, Shashkova et al 1999, Manecki et al 2000b, McGowen et al 2001, McGrellis et al 2001, Lusvardi et al 2002, Basta McGowen 2004, Lundager et al 2004, Raicevic et al 2005, Manecki et al 2006, Marchat et al 2007, Matusik et al 2008. This method, which is well known in the literature as in situ phosphate formation has convincing advantages.…”

Section: Introductionmentioning

confidence: 99%

Aqueous cadmium removal by hydroxylapatite and fluoroapatite

Matusik¹,

Bajda²,

Manecki³

2012

geol

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Reducing the bioavailability of toxic heavy metals in groundwaters and urban soils by phosphate addition is an effective technique described in the literature. It is based on the reaction between metal ions and phosphates and results in the precipitation of metal substituted phosphate phases. The formed phosphates are highly insoluble and thermodynamically stable over almost entire pH and Eh range. In the presented study the efficiency and mechanism of cadmium uptake by synthetic hydroxylapatite and natural fluoroapatite was examined within the pH range of 3 7 for different reaction times (2 1440 hours). The solids after reactions were characterized by XRD and SEM-EDS. Percentage reduction of cadmium concentration in the experiments with fluoroapatite and hydroxylapatite, regardless of pH, did not exceed 17% and 25%, respectively. Cadmium uptake from the solution mainly resulted from the formation of cadmium phosphates and/or Ca-Cd phosphate solid solutions on the apatites surface. The release rate of phosphate ions by hydroxylapatite was relatively high. This promoted crystallization of a large number of small crystals. In turn dissolution of fluoroapatite was slower and thus the formation of large crystals was observed. There was no clear evidence for cadmium-calcium ion-exchange mechanism.

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In situ lead immobilization by apatite

Cited by 674 publications

References 10 publications

Peer Reviewed: Reducing Children's Risk from Lead in Soil

Peer Reviewed: Reducing Children's Risk from Lead in Soil

Lead Speciation in Artificial Human Digestive Fluid

Aqueous cadmium removal by hydroxylapatite and fluoroapatite

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