Structural Modification of Calcium Hydroxyapatite Induced by Sorption of Cadmium Ions

Jeanjean, J.; Vincent, U.; Fédoroff, M.

doi:10.1006/jssc.1994.1010

Cited by 109 publications

(54 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As a first approximation, CDHA may be considered as HA with some ions missing. [87] According to the chemical formula of CDHA (Table 2), there are vacant calcium ion sites (mainly Ca2 sites, [88,89] see HA below) and hydroxide ion sites in the crystal structure of this compound. However, little is known about the vacancies of phosphate ions: in CDHA, part of the phosphate ions is either protonated or substituted by other ions (e.g.…”

Section: Biomineralization Of Calcium Phosphatesmentioning

confidence: 99%

Biological and Medical Significance of Calcium Phosphates

Dorozhkin¹,

Epple²

2002

Angew. Chem. Int. Ed.

1,836

1,252

View full text Add to dashboard Cite

The inorganic part of hard tissues (bones and teeth) of mammals consists of calcium phosphate, mainly of apatitic structure. Similarly, most undesired calcifications (i.e. those appearing as a result of various diseases) of mammals also contain calcium phosphate. For example, atherosclerosis results in blood-vessel blockage caused by a solid composite of cholesterol with calcium phosphate. Dental caries result in a replacement of less soluble and hard apatite by more soluble and softer calcium hydrogenphosphates. Osteoporosis is a demineralization of bone. Therefore, from a chemical point of view, processes of normal (bone and teeth formation and growth) and pathological (atherosclerosis and dental calculus) calcifications are just an in vivo crystallization of calcium phosphate. Similarly, dental caries and osteoporosis can be considered to be in vivo dissolution of calcium phosphates. On the other hand, because of the chemical similarity with biological calcified tissues, all calcium phosphates are remarkably biocompatible. This property is widely used in medicine for biomaterials that are either entirely made of or coated with calcium phosphate. For example, self-setting bone cements made of calcium phosphates are helpful in bone repair and titanium substitutes covered with a surface layer of calcium phosphates are used for hip-joint endoprostheses and tooth substitutes, to facilitate the growth of bone and thereby raise the mechanical stability. Calcium phosphates have a great biological and medical significance and in this review we give an overview of the current knowledge in this subject.

show abstract

Section: Biomineralization Of Calcium Phosphatesmentioning

confidence: 99%

Biological and Medical Significance of Calcium Phosphates

Dorozhkin¹,

Epple²

2002

Angew. Chem. Int. Ed.

1,836

1,252

View full text Add to dashboard Cite

show abstract

“…In addition to Pb, phosphate rock can also remove Zn and Cd from aqueous solutions. The possible mechanisms for metal retention by phosphate minerals included: (1) ion exchange pro cesses at the surface of PR (Middelburg and Comans, 1991;Xu et al, 1994); (2) surface complexation (Xu et al, 1994); (3) precipitation of some amorphous to poorly crystalline, mixed metal phosphates (Ma et al, 1995); and (4) substitution of Ca in PR by other metals during recrystallization (coprecipitation) (Chen et al, 1997;Jeanjean et al, 1994;Xu et al, 1994). However, it is difficult to quantify the relative contribution from each mechanism that is responsible for metal removal and it appears that all four mechanisms may work together.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of lead, copper, and zinc retention by phosphate rock

Cao

Lena

Rhue

et al. 2004

Environmental Pollution

332

View full text Add to dashboard Cite

''Capsule'': Phosphate-induced formation of fluoropyromorphite is primarily responsible for Pb immobilization by phosphate rock, whereas Cu and Zn retention is mainly attributable to the surface adsorption or complexation. AbstractThe solideliquid interface reaction between phosphate rock (PR) and metals (Pb, Cu, and Zn) was studied. Phosphate rock has the highest affinity for Pb, followed by Cu and Zn, with sorption capacities of 138, 114, and 83.2 mmol/kg PR, respectively. In the PbeCueZn ternary system, competitive metal sorption occurred with sorption capacity reduction of 15.2%, 48.3%, and 75.6% for Pb, Cu, and Zn, respectively compared to the mono-metal systems. A fractional factorial design showed the interfering effect in the order of Pb O Cu O Zn. Desorption of Cu and Zn was sensitive to pH change, increasing with pH decline, whereas Pb desorption was decreased with a strongly acidic TCLP extracting solution (pH ¼ 2:93). The greatest stability of Pb retention by PR can be attributed to the formation of insoluble fluoropyromorphite [Pb 10 (PO 4 ) 6 F 2 ], which was primarily responsible for Pb immobilization (up to 78.3%), with less contribution from the surface adsorption or complexation (21.7%), compared to 74.5% for Cu and 95.7% for Zn. Solution pH reduction during metal retention and flow calorimetry analysis both supported the hypothesis of retention of Pb, Cu, and Zn by surface adsorption or complexation. Flow calorimetry indicated that Pb and Cu adsorption onto PR was exothermic, while Zn sorption was endothermic. Our research demonstrated that PR can effectively remove Pb from solutions, even in the presence of other heavy metals (e.g. Cu, Zn).

show abstract

“…However, previous research suggested that the reaction mechanisms for metal immobilization by phosphate minerals include: (a) ion exchange process; (b) surface complexation; (c) dissolution of the original phosphate minerals and precipitation of new metal phosphates; and, (d) substitution of Ca in phosphate by other metals during recrystallization (co-precipitation) (Jeanjean et al, 1994;Ma et al, 1994). Several groups suggested that phosphate anions, which can be provided through dissolution of MCP, reacted with lead cations and formed Pb 10 (PO 4 ) 6 (OH) 2 (Ma et al, 1994;Xu and Schwartz, 1994;Zhang et al, 1997) Similarly, it also proved that Cd can be fixed in the formation of Cd-containing phosphates (Mignardi et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Immobilization of heavy metals in sludge using phosphoric acid and monobasic calcium phosphate

Tang

Zhou

Xie

2013

J. Zhejiang Univ. Sci. A

View full text Add to dashboard Cite

Abstract:The purpose of this research is to investigate the potential of pre-treatment with phosphoric acid (PA) and monobasic calcium phosphate (MCP) for the stabilization of heavy metals in sludge and its bottom ash. The tannery sludge samples were collected in Wenzhou, China and heavily contaminated with heavy metals, such as Pb, Cr and so on. The samples were pre-treated with PA or MCP. Then XRD and TCLP tests were adopted as the evaluating methods to characterize the Pb, Cr, Cu, Zn and Cd immobilization in the pre-treated sludge and its bottom ash. The results showed that this treatment effectively immobilized Pb and Cd in the sludge, lightly stabilized the metal Cu, and adversely, enhanced the leachability of Zn. After incineration at 900 °C, Pb and Cr in the bottom ash of pre-treated sludge were significantly stabilized due to the formation of their highly thermostable phosphates and pyromorphite-like minerals during the incineration process. However, an increase of Cu and Zn solubility was observed which might be attributable to the acidification of sludge due to the addition of PA or MCP.

show abstract

Structural Modification of Calcium Hydroxyapatite Induced by Sorption of Cadmium Ions

Cited by 109 publications

References 0 publications

Biological and Medical Significance of Calcium Phosphates

Biological and Medical Significance of Calcium Phosphates

Mechanisms of lead, copper, and zinc retention by phosphate rock

Immobilization of heavy metals in sludge using phosphoric acid and monobasic calcium phosphate

Contact Info

Product

Resources

About