Selective removal of lead from calcareous polluted soils using the Ca-EDTA salt

Theodoratos, P; Papassiopi, N; Georgoudis, T; Kontopoulos, A

dc.contributor.author	Theodoratos, P	en
dc.contributor.author	Papassiopi, N	en
dc.contributor.author	Georgoudis, T	en
dc.contributor.author	Kontopoulos, A	en
dc.date.accessioned	2014-03-01T01:15:52Z
dc.date.available	2014-03-01T01:15:52Z
dc.date.issued	2000	en
dc.identifier.issn	0049-6979	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/13789
dc.subject	contaminated soil	en
dc.subject	EDTA	en
dc.subject	lead	en
dc.subject	removal of lead	en
dc.subject	treatment of calcareous soil	en
dc.subject.classification	Environmental Sciences	en
dc.subject.classification	Meteorology & Atmospheric Sciences	en
dc.subject.classification	Water Resources	en
dc.subject.other	EXTRACTIVE DECONTAMINATION	en
dc.subject.other	CONTAMINATED SOIL	en
dc.subject.other	RECOVERY	en
dc.subject.other	METALS	en
dc.subject.other	PB	en
dc.subject.other	ACID	en
dc.title	Selective removal of lead from calcareous polluted soils using the Ca-EDTA salt	en
heal.type	journalArticle	en
heal.identifier.primary	10.1023/A:1005295119231	en
heal.identifier.secondary	http://dx.doi.org/10.1023/A:1005295119231	en
heal.language	English	en
heal.publicationDate	2000	en
heal.abstract	EDTA is a powerful chelating reagent which has been often proposed for the decontamination of lead polluted soils. Despite the pronounced selectivity of this reagent for Pb, a low degree of utilisation is observed when treating calcareous soils, due to the co-dissolution of calcite. This study demonstrates that it is possible to suppress calcite dissolution and optimise the degree of EDTA utilisation, using the calcium salt of EDTA, instead of the common sodium salts. Initial experiments, which were carried out mixing pure cerrusite (PbCO3) with a Na(2)CaEDTA solution, have shown that Pb is quantitatively solubilised, while calcium precipitates in the form of aragonite. The performance of this reagent in the decontamination of soils has been tested on a soil sample from Lavrion (Greece) containing 7.3-8.8% of Ca and heavily polluted with Pb at levels up to 3.5%. The parameters which were tested include the reaction time, the stoichiometric excess of Na(2)CaEDTA with respect to Pb and the effect of successive treatment stages with fresh Na(2)CaEDTA solutions. The experimental results have shown that long reaction times, exceeding 24 hr, are required in order to obtain sufficient Pb removal and preserve the calcium content of the soil. Lead extraction increases from 27 to 40% prolonging the reaction time from 1 to 24 hr at Na(2)CaEDTA/Pb = 1 mol/mol. Increasing the Na(2)CaEDTA/Pb molar ratio from 1 to 3.5 mol/mol, enhances the dissolution of Pb from 40 to 53%, which is not proportional to the stoichiometric excess supplied. The efficiency of Ph removal is maximized, up to 75%, applying three successive leaching stages. The major benefit of Na(2)CaEDTA in comparison with the disodium EDTA salt is the preservation of soil calcite. The initial calcium content of the soil was found to increase by 4% using the Ca salt; on the contrary, the treatment with Na(2)H(2)EDTA under similar experimental conditions has resulted in dissolving 27% of soil Ca.	en
heal.publisher	KLUWER ACADEMIC PUBL	en
heal.journalName	WATER AIR AND SOIL POLLUTION	en
dc.identifier.doi	10.1023/A:1005295119231	en
dc.identifier.isi	ISI:000088697400006	en
dc.identifier.volume	122	en
dc.identifier.issue	3-4	en
dc.identifier.spage	351	en
dc.identifier.epage	368	en