A Crystallographic Study of the Sorption of Cadmium on Calcium Hydroxyapatites: Incidence of Cationic Vacancies

Jeanjean, J.; McGrellis, Siobhan A.; Rouchaud, J.C.; Fédoroff, M.; Rondeau, Annette; Perocheau, S.; Dubis, Alina T.

doi:10.1006/jssc.1996.0329

Cited by 52 publications

(45 citation statements)

References 7 publications

(9 reference statements)

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“…It was not as remarkable as for Pb 2+ case, but corresponds to 12% Cd 2+ removal and 5% Zn 2+ removal, representing a significant contribution to the immobilization process if accounting the total percent removal of these metals at equilibrium, i.e., 18% and 15% for Cd 2+ and Zn 2+ , respectively. This observation is in agreement with the main mechanisms of zinc and cadmium ions immobilization by apatitelike materials, which includes surface complexation, sorption, and ion exchange (Corami et al 2008;Dybowska et al 2009;Jeanjean et al 1996;Middelburg and Comans 1991;Sery et al 1996;Xu et al 1994). One of the principal mechanisms associated to Zn 2+ and Cd 2+ sorption appears to be complexation on ≡POH (and ≡PO − ) sites of apatite surface.…”

Section: Sorption Experiments For Cadmium and Zinc Ionssupporting

confidence: 89%

Water Remediation Using Calcium Phosphate Derived From Marine Residues

Silva

Costa

Vilar

et al. 2011

Water Air Soil Pollut

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The processing of natural resources in marine and freshwater ecosystems, directly operated by industries related to maritime sector, contributes annually to several million tons of waste. The reuse and economic recovery of this waste would be very desirable and profitable, either economically or environmentally. In this work, the remediation of hazardous divalent metal ions from aqueous solutions using biological apatites derived from marine residues was addressed. The biological apatite (calcium phosphate particles) was produced by heat treatment of fish bones. Experimental sorption studies of kinetics and equilibrium of the metal ions as well as an evaluation of competitive sorption behavior for lead immobilization were carried out in batch operation mode. The efficiency and mechanisms of lead sorption on two different particle sizes of calcium phosphate from aqueous solution were investigated. The results showed a high adsorption capacity of the biosorbent for Pb 2+ (above 370 mg/g ads. ), in opposition to Cd 2+ and Zn 2+ . For the case of low initial concentrations of the metal ion, reducing the biosorbent particles size increases the sorption rate. It was possible to verify that lead immobilization proceeds with a rapid surface complexation of the lead on the sorption sites before partial dissolution of calcium phosphate and formation of pyromorphitelike compounds. By the selectivity experiments, performed using binary systems-Pb/Cd and Pb/Znit was evidenced a competitive process between the divalent ions, which leads to a considerable decrease on the adsorption capacity of the adsorbent material for all the metals.

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Section: Sorption Experiments For Cadmium and Zinc Ionssupporting

confidence: 89%

Water Remediation Using Calcium Phosphate Derived From Marine Residues

Silva

Costa

Vilar

et al. 2011

Water Air Soil Pollut

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“…Hydrated hydroxyapatites may also be prepared at 70-90 ~ by adding NH 3 or NaOH into Ca(NO3) 2 and (NH4)2HPO 4 solutions [20,21]. The formula of the yielded precipitates may be written as CaxNay-(PO4)z(OH)~ nH20, where x, y, z, m and n values are determined by the solution concentration, pH value etc.…”

Section: A Brief Review Of Apatitesmentioning

confidence: 99%

Synthesis and ionic conduction of apatite-type materials

Tao

Irvine

2000

Ionics

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Abstract. Apatite is a mineral with general formula Ml0(XO4)6Z2, where M are metallic elements such as Li § Na +, K*, Ca 2 § Sr z+, Ba 2 § Ln 3 § etc.; X = P, V, S, Si, Ge, Re, Cr etc; Z = F-, CI-, I-, OH-, O z-, S a-etc. Some materials with apatite structure (S.G. P63/m) exhibit quite high cationic (Li § H § etc.) and/or anionic (F-, C1-etc.) conduction. Recently, it was reported that some rare earth silicates, e.g., Lam(SiO4)603, exhibit quite high oxide-ion conductivity. In this paper, we discuss chemical composition, structure, synthetic procedure and ionic conduction of apatite-type materials. Recent improvements are briefly reviewed. High ionic conductivity has been observed for both cation deficient, oxygen stoichiometric La9.33(5iO4)60 a and cation stoichiometric, oxygen excess Lalo(SiO4)603 compositions. Grain boundary conductivity is usually low, which tends to dominate the impedance response. The resistance, particularly the grain boundary resistance is also found to depend on pO a.

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“…It is well established in literature that cadmium uptake by HAP is a result of adsorption of cadmium on apatite surface followed by ion exchange with calcium (Jeanjean et al 1996, McGrellis et al 2001, Lusvardi et al 2002, Marchat et al 2007). However, our results show direct evidence of dissolution-precipitation mechanism for both minerals.…”

Section: Sem Analysesmentioning

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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A Crystallographic Study of the Sorption of Cadmium on Calcium Hydroxyapatites: Incidence of Cationic Vacancies

Cited by 52 publications

References 7 publications

Water Remediation Using Calcium Phosphate Derived From Marine Residues

Water Remediation Using Calcium Phosphate Derived From Marine Residues

Synthesis and ionic conduction of apatite-type materials

Aqueous cadmium removal by hydroxylapatite and fluoroapatite

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