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Article: In situ transformation of labile lead compounds to pyromorphites

TitleIn situ transformation of labile lead compounds to pyromorphites
Authors
KeywordsLead Contamination
Pb Immobilization
Phosphate Treatment
Pyromorphite Formation
Soil Remediation
Issue Date2007
Citation
Land Contamination And Reclamation, 2007, v. 15 n. 4, p. 453-458 How to Cite?
AbstractPhosphate-induced lead (Pb) immobilization that transforms labile species to pyromorphites is being tested as a cost-effective remedial alternative for reducing the health and ecological risks associated with Pb-contaminated soil. Several studies have revealed that the phosphate-induced transformation of soil Pb was incomplete and in vitro Pb bioavailability over-estimated the reduction of in vivo bioavailability of the treated soils. A laboratory study was conducted to synthesize pyromorphites from labile Pb compounds under simulated soil surface moisture conditions, and to examine the reactivity of the labile compounds and the mechanism of Pb transformation. Two highly labile compounds: lead carbonate (PbCO3) and lead oxide (PbO), were selected to react with phosphoric acid (H3PO4) at a Pb:P molar ratio of 1:5 and incubated under the conditions of naturally wet-dry cycles. The lead mineralogy of the mixtures was identified by x-ray diffraction (XRD), and the elemental composition characterized by electron beam microspectroscopy (SEM-WDS). Results indicated that the dissolution of labile Pb compounds and the initial formation of pyromorphites were kinetically rapid. Nevertheless, only 25-30% of the mixtures were identified as pyromorphites, and the remaining portion was accounted for by lead phosphates after reaction. This study suggests that pyromorphites form through intermediate lead phosphates, rather than precipitation from Pb ions as was previously described. Formation of such intermediate lead phosphates during the transformation to pyromorphites could result in limited pyromorphite formation, which may account for the incomplete Pb immobilization in H3PO4-treated contaminated soil, and the discrepancy between the in vivo and in vitro bioavailability of soil Pb. © 2007 EPP Publications Ltd.
Persistent Identifierhttp://hdl.handle.net/10722/151232
ISSN
2013 SCImago Journal Rankings: 0.102
References

 

DC FieldValueLanguage
dc.contributor.authorYang, Jen_US
dc.contributor.authorDeng, BLen_US
dc.contributor.authorLi, YLen_US
dc.contributor.authorZhang, CLen_US
dc.date.accessioned2012-06-26T06:19:04Z-
dc.date.available2012-06-26T06:19:04Z-
dc.date.issued2007en_US
dc.identifier.citationLand Contamination And Reclamation, 2007, v. 15 n. 4, p. 453-458en_US
dc.identifier.issn0967-0513en_US
dc.identifier.urihttp://hdl.handle.net/10722/151232-
dc.description.abstractPhosphate-induced lead (Pb) immobilization that transforms labile species to pyromorphites is being tested as a cost-effective remedial alternative for reducing the health and ecological risks associated with Pb-contaminated soil. Several studies have revealed that the phosphate-induced transformation of soil Pb was incomplete and in vitro Pb bioavailability over-estimated the reduction of in vivo bioavailability of the treated soils. A laboratory study was conducted to synthesize pyromorphites from labile Pb compounds under simulated soil surface moisture conditions, and to examine the reactivity of the labile compounds and the mechanism of Pb transformation. Two highly labile compounds: lead carbonate (PbCO3) and lead oxide (PbO), were selected to react with phosphoric acid (H3PO4) at a Pb:P molar ratio of 1:5 and incubated under the conditions of naturally wet-dry cycles. The lead mineralogy of the mixtures was identified by x-ray diffraction (XRD), and the elemental composition characterized by electron beam microspectroscopy (SEM-WDS). Results indicated that the dissolution of labile Pb compounds and the initial formation of pyromorphites were kinetically rapid. Nevertheless, only 25-30% of the mixtures were identified as pyromorphites, and the remaining portion was accounted for by lead phosphates after reaction. This study suggests that pyromorphites form through intermediate lead phosphates, rather than precipitation from Pb ions as was previously described. Formation of such intermediate lead phosphates during the transformation to pyromorphites could result in limited pyromorphite formation, which may account for the incomplete Pb immobilization in H3PO4-treated contaminated soil, and the discrepancy between the in vivo and in vitro bioavailability of soil Pb. © 2007 EPP Publications Ltd.en_US
dc.languageengen_US
dc.relation.ispartofLand Contamination and Reclamationen_US
dc.subjectLead Contaminationen_US
dc.subjectPb Immobilizationen_US
dc.subjectPhosphate Treatmenten_US
dc.subjectPyromorphite Formationen_US
dc.subjectSoil Remediationen_US
dc.titleIn situ transformation of labile lead compounds to pyromorphitesen_US
dc.typeArticleen_US
dc.identifier.emailLi, YL:yiliang@hkucc.hku.hken_US
dc.identifier.authorityLi, YL=rp01354en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.2462/09670513.859en_US
dc.identifier.scopuseid_2-s2.0-37549042008en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-37549042008&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume15en_US
dc.identifier.issue4en_US
dc.identifier.spage453en_US
dc.identifier.epage458en_US
dc.identifier.scopusauthoridYang, J=15039112900en_US
dc.identifier.scopusauthoridDeng, BL=7101938052en_US
dc.identifier.scopusauthoridLi, YL=27171876700en_US
dc.identifier.scopusauthoridZhang, CL=38260898100en_US
dc.identifier.citeulike2144844-

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