Kinetics of hydroxyapatite precipitation at pH 7.4 to 8.4

Inskeep, William P.; Silvertooth, J. C.

doi:10.1016/0016-7037(88)90012-9

Cited by 59 publications

(31 citation statements)

References 28 publications

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“…The precipitation of calcium phosphate from aqueous solution is somewhat complicated due to the possible occurrence of several different calcium phosphates with or without hydrogen/hydroxide group, depending on the solution composition and the pH value [35][36][37]. These phosphates salts include dicalcium phosphate (DCP), dicalcium phosphate dehydrate (DCPD), tricalcium phosphate (TCP), octacalcium phosphate (OCP), HAP, amorphous calcium phosphate (ACP), and so on [38,39].…”

Section: Mechanism Of Mineralizationmentioning

confidence: 99%

Rapid biomimetic mineralization of chitosan scaffolds with a precursor sacrificed method in ethanol/water mixed solution

Li¹,

Zhao²,

Ding³

et al. 2011

Express Polym. Lett.

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Abstract. Biomimetic mineralization was performed on a large scale by a rapid and efficient approach. Chitosan scaffolds were placed in a mixed solution of urea, ethanol and distilled water, followed by the introduction of dibasic sodium phosphate (0.1M) and calcium chloride (0.1M) with the molar ratio of 1.67. These mixed solvents was then adjusted to weakly alkaline by adding sodium hydroxide solution. Finally the reaction mixture was sealed and kept at 80ºC for predetermined time. The composition and morphology of the apatite and the hybrid scaffolds were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR) and environmental scanning electron microscopy (ESEM). The mechanism of nucleation and growth of crystals was discussed as well. The results revealed that chitosan scaffolds improved the crystallinity of hydroxyapatite (HAP) crystals. With the extension of mineralization time, the mineral layers on the outer surface and inner section of chitosan scaffolds increased as well. Furthermore, the compressive strength and modulus of the HAP-chitosan scaffolds biocomposites increased to 0.55±0.003 and 29.29±1.25 MPa respectively. Such one-pot approach may be extended to the mineralization of other materials and will have a broad application in the future.

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Section: Mechanism Of Mineralizationmentioning

confidence: 99%

Rapid biomimetic mineralization of chitosan scaffolds with a precursor sacrificed method in ethanol/water mixed solution

Li¹,

Zhao²,

Ding³

et al. 2011

Express Polym. Lett.

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“…Neither of these methods can fully guarantee a reliable selection of minerals to include in a model. Most prior studies have been carried out at low ionic strength and in pure solutions (Inskeep andSilvertooth 1988, Nancollas and, and it is not known how well the results translate into real wastewater (Valsami-Jones 2001). Further, chemical equilibrium predictors do not capture kinetic effects (Wiechers et al 1975).…”

Section: Minerals Precipitation Modelling Approachmentioning

confidence: 99%

“…Both to account for seasonality and for artificial temperature variations in a plant-wide model, temperature correction of kinetics should be applied and an Arrhenius-style kinetic correction of kcryst is suggested (Equation (3.9)). There is still a general lack of activation energy (Ea) values for all the relevant minerals in wastewater , although some values are available for relevant minerals (Boskey and Posner 1973, Harmandas and Koutsoukos 1996, Inskeep and Silvertooth 1988. The activation energies vary from mineral to mineral, perhaps related to the extent of crystallinity and perhaps also to the mechanism of crystal growth (Inskeep andSilvertooth 1988, Mullin 2001).…”

Section: Optional Model Correctionsmentioning

confidence: 99%

“…There is still a general lack of activation energy (Ea) values for all the relevant minerals in wastewater , although some values are available for relevant minerals (Boskey and Posner 1973, Harmandas and Koutsoukos 1996, Inskeep and Silvertooth 1988. The activation energies vary from mineral to mineral, perhaps related to the extent of crystallinity and perhaps also to the mechanism of crystal growth (Inskeep andSilvertooth 1988, Mullin 2001). For example, activation energy values are 40 kJ.mole -1 for amorphous iron sulphide (Harmandas and Koutsoukos 1996), 44 kJ.mole -1 for DCPD (Nancollas 1973), 70 kJ.mole -1 for struvite (Yu et al 2013) and up to 185 kJ.mole -1 for hydroxyapatite (Inskeep and Silvertooth 1988).…”

Section: Optional Model Correctionsmentioning

confidence: 99%

“…The activation energies vary from mineral to mineral, perhaps related to the extent of crystallinity and perhaps also to the mechanism of crystal growth (Inskeep andSilvertooth 1988, Mullin 2001). For example, activation energy values are 40 kJ.mole -1 for amorphous iron sulphide (Harmandas and Koutsoukos 1996), 44 kJ.mole -1 for DCPD (Nancollas 1973), 70 kJ.mole -1 for struvite (Yu et al 2013) and up to 185 kJ.mole -1 for hydroxyapatite (Inskeep and Silvertooth 1988). …”

Section: Optional Model Correctionsmentioning

confidence: 99%

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Dynamic modelling of minerals precipitation in wastewater treatment

Mbamba¹

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In wastewater treatment, there is an increasing focus on nutrient and energy recovery and a reduction in energy consumption to counter climate change. Because of this, integrated mathematical modelling platforms are required to support plant-wide developments making use of emerging, resilient and environmental-friendly technologies. A reliable model description of a wastewater treatment plant should include both biology and physico-chemistry. However, existing standard models used across the wastewater sector have a biological focus with over-simplified descriptions of important physicochemistry, especially with minerals precipitation which is a very important class of physicochemical reactions.As part of development of a more widely applicable physicochemical framework, this thesis sought to identify a suitable minerals precipitation modelling approach that could give reasonable results in mainstream use with wastewater treatment. This research aim was approached in three steps. Firstly a review of available modelling approaches suggested a simple equilibrium kinetic-based modelling approach could be feasible. This approach was then validated in a simple system of calcite in synthetic solutions using pH titration experiments with the reliable Constant Composition Method (CCM).Further statistical analysis focused on clarifying key environmental factors that influence calcite precipitation to determine whether these are necessary to include in a model. Secondly, the proposed model approach was further tested on different types of wastewater and for multiple parallel precipitation reactions. Experiments included dynamic titration or aeration with synthetic wastewater and real wastewater. Thirdly, the general physicochemical modelling approach was implemented in a plant-wide platform together with standard biological models, namely activated sludge model No 2 (ASM2d) and Anaerobic Digestion Model No. 1 (ADM1). The plant-wide model evaluation compared simulations with real data from a full-scale wastewater treatment plant, and used steadystate, dynamic and scenario analyses to test the model performance.Experimental evidence for calcite precipitating in synthetic aqueous solutions, suggested that minerals precipitation kinetics could be reliably described with a 1 st order dependency on mineral Further testing for multi-species systems in real wastewater indicated that precipitation was dominated by the mineral struvite, forming together with varied and minor amounts of calcium phosphate and some calcium carbonate. Kinetic rate coefficients (kcryst), which were statistically fitted, were generally in the range 0.35-11.6 h -1 with 95% confidence intervals of 10-80% relative.The results confirmed that the baseline model approach provided a statistically good fit of measured pH, dissolved calcium, magnesium, total inorganic carbon and phosphate. With this application, the precipitation modelling approach offered the advantage of only requiring a minimal number of empirical fitted parameters (kcryst values), res...

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Nanosized Hydroxyapatite Precipitation from Homogeneous Calcium/Citrate/Phosphate Solutions Using Microwave and Conventional Heating

López‐Macipe¹,

1998

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ture of the predominant species in the gel precursor. This phenomenon allows us to direct the crystallization reaction to the desired aluminophosphate phase simply by controlling the gel precursor pH. ExperimentalThe reaction gels of composition n-DPA:P 2 O 5 :Al 2 O 3 :40H 2 O, using pseudoboehmite alumina (Condea, Pural SB), phosphoric acid 85 % (Aldrich), and n-DPA (n-dipropylamine 99 %, Aldrich) were prepared in a similar way to that described by Davis et al. [16]. A 1 L batch reactor was filled with 500 mL of the reaction gel and stirred at 350 rpm. A heating blanket was used to achieve and maintain reflux (99 C). The heating rate was 5 /min. During heating, the gel pH increased spontaneously from 3.5 to 6. The control of the pH to within ±0.1 pH units was achieved using a pH-stat unit, by adding 3 M HNO 3 . At the end of each experiment, the reactor was quenched with cold water and the products recovered by slurrying the reactor contents with water, decanting the supernatant liquid, filtering, washing with deionized water, and drying overnight at room temperature. The products were characterized by quantitative X-ray diffraction (XRD) using a Rigaku Rotaflex RU-200B instrument with Cu Ka radiation (1.5418 ) and AlPO 4 hydrates of approximately 95 % purity as standards.

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Kinetics of hydroxyapatite precipitation at pH 7.4 to 8.4

Cited by 59 publications

References 28 publications

Rapid biomimetic mineralization of chitosan scaffolds with a precursor sacrificed method in ethanol/water mixed solution

Rapid biomimetic mineralization of chitosan scaffolds with a precursor sacrificed method in ethanol/water mixed solution

Dynamic modelling of minerals precipitation in wastewater treatment

Nanosized Hydroxyapatite Precipitation from Homogeneous Calcium/Citrate/Phosphate Solutions Using Microwave and Conventional Heating

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