Apparent solubilities of two amorphous calcium phosphates and of octacalcium phosphate in the temperature range 30–42°C

Christoffersen, Margaret R.; Christoffersen, J.; Kibalczyc, W.

doi:10.1016/0022-0248(90)90079-z

Cited by 147 publications

(110 citation statements)

References 14 publications

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“…c Calculated from raw data given by Christoffersen et al (1990) (Johansson and Gustafsson, 2000), and b) the materials from the present study, in which equilibrium was approached from undersaturation. The dotted line indicates the suggested solubility constant ( = 10 -27.94 at 21 o C) for the ATCP phase formed.…”

Section: Discussionmentioning

confidence: 99%

“…As shown in Fig. 3, many samples were close to equilibrium with the less noncrystalline ATCP termed ACP2 (Christoffersen et al, 1990). Moreover, the pH dependence of the ion activity products were in better agreement with ACP2 than with OCP, which suggested that solubility control by ACP2 (or ATCP) was slightly more likely although a prominent role for OCP could not be ruled out from these observations only.…”

Section: Solubility Of Phosphate In the Filter Materialsmentioning

confidence: 91%

“…Calculated ion activity products were compared to solubility constants given in the literature (Table 3). For ATCP, for which few solubility data exists, constants were calculated from raw data given for two amorphous calcium phosphates of varying crystallinity, referred to as ACP1 and ACP2 by the authors (Christoffersen et al, 1990). These thermodynamic data should only be considered as rough estimates, not least because the observed Ca:P ratios in the precipitates were between 1.28 and 1.38, which is slightly less than the ideal ratio of 1.5.…”

Section: Solubility Studiesmentioning

confidence: 99%

“…These thermodynamic data should only be considered as rough estimates, not least because the observed Ca:P ratios in the precipitates were between 1.28 and 1.38, which is slightly less than the ideal ratio of 1.5. The solubility data for OCP were also calculated from experiments conducted by Christoffersen et al (1990).…”

Section: Solubility Studiesmentioning

confidence: 99%

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Phosphate removal by mineral-based sorbents used in filters for small-scale wastewater treatment

et al. 2008

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The mineral-based sorbents Filtra P, Polonite ® , natural wollastonite and water-cooled blast furnace slag (WCBFS) were studied in terms of their PO 4 removal performance. Results from a long-term column experiment showed that both Filtra P and Polonite ® removed > 95 % of PO 4 from the applied synthetic solution, and that the used filter materials had accumulated several (1.9-19) g kg -1 P. Phosphorus was removed also by natural wollastonite and WCBFS, but these materials were less efficient. Batch experiments on the used materials showed that the solubility PO 4 was considerably larger than the one expected for crystalline Ca phosphates such as hydroxyapatite, and results from investigations with attenuated total reflectanceFourier-Transform infrared spectroscopy (ATR-FTIR) on the Filtra P material showed that the formed P phase was not crystalline. These evidence suggest that a soluble amorphous tricalcium phosphate (ATCP) was formed in the mineral-based sorbents; the apparent solubility constant on dissolution was estimated to log K s = -27.94 (±0.31) at 21 o C. However, since only up to 18 % of the accumulated PO 4 was readily dissolved in the experiments it cannot be excluded that part of the phosphorus had crystallized to slightly less soluble phases.In conclusion, Filtra P and Polonite are two promising mineral-based sorbents for phosphorus removal, and at least part of the accumulated phosphorus is present in a soluble form, readily available to plants.

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Section: Discussionmentioning

confidence: 99%

Section: Solubility Of Phosphate In the Filter Materialsmentioning

confidence: 91%

Section: Solubility Studiesmentioning

confidence: 99%

Section: Solubility Studiesmentioning

confidence: 99%

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Phosphate removal by mineral-based sorbents used in filters for small-scale wastewater treatment

et al. 2008

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“…Octacalcium phosphate was synthesized at 42 o C using the method of Christoffersen et al (19). These authors also presented methods to synthesize two versions of ACP termed ACP1 and ACP2.…”

Section: Preparation Of Xanes Standardsmentioning

confidence: 99%

XANES Speciation of P in Environmental Samples: An Assessment of Filter Media for on-Site Wastewater Treatment

Eveborn

Gustafsson

Hesterberg

et al. 2009

Environ. Sci. Technol.

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X-ray absorption near edge structure (XANES) is a useful technique for characterisation of chemical species of phosphorus in complex environmental samples. To develop and evaluate 1 bed filters as sustainable on-site wastewater treatment solutions, our objective in this study was to determine the chemical forms of accumulated phosphorus in a selection of promising filter materials: Filtralite P, Filtra P, Polonite, Absol, blast furnace slag, and wollastonite.Full-scale operational wastewater-treatment systems were sampled and in addition, filter samples collected from laboratory studies provided access to additional media and complementary samples. Phosphorus species were characterized using phosphorus K-edge XANES spectroscopy, complemented by X-ray powder diffraction (XRPD) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). No systematic differences could be seen in the results between laboratory-and full-scale samples. All six filter media contained significant amounts of crystalline calcium phosphates. Some samples also contained amorphous calcium phosphate (>60% of total P in Absol). In Filtralite P and blast furnace slag, more than 35% of the accumulated phosphorus was associated with Fe or Al. Both the power and shortcomings of XANES analysis for characterizing P species in these filter media are discussed.

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Calcium and Calcium Alloys

Hluchan¹,

Pomerantz²

2000

Ullmann's Encyclopedia of Industrial Chemistry

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Apparent solubilities of two amorphous calcium phosphates and of octacalcium phosphate in the temperature range 30–42°C

Cited by 147 publications

References 14 publications

Phosphate removal by mineral-based sorbents used in filters for small-scale wastewater treatment

Phosphate removal by mineral-based sorbents used in filters for small-scale wastewater treatment

XANES Speciation of P in Environmental Samples: An Assessment of Filter Media for on-Site Wastewater Treatment

Calcium and Calcium Alloys

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