A solubility and surface complexation study of a non-stoichiometric hydroxyapatite

Bengtsson, Anders; Shchukarev, Andrei; Persson, Per; Sjöberg, Staffan

doi:10.1016/j.gca.2008.09.034

Cited by 93 publications

(85 citation statements)

References 41 publications

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“…According to the compilation of experimental determinations of P-dissolution rates of HAP and FAP by Palandri and Kharaka (2004), the dissolution rate of HAP is found to be about an order of magnitude slower than that of FAP under highly acidic conditions (K(HAP) = 10 −4.29 and K(FAP) = 10 −3.73 for pH = 0), while under neutral conditions, HAP is found to dissolve 2 orders of magnitude faster than FAP (K(HAP) = 10 −6 and K(FAP) = 10 −8 for pH = 7). Moreover, HAP is measured to have an almost 8 times larger specific surface area (80.5 m 2 g −1 , Bengtsson et al, 2009) compared to that of FAP (10.7 m 2 g −1 ), which is in agreement with the measured specific surface areas of 8.1-16 m 2 g −1 for sedimentary FAP (Guidry and Mackenzie, 2003). Guidry and Mackenzie (2003) have experimentally derived different rate constants (K) for FAP dissolution ranging from 5.75 × 10 −6 to 6.53 × 10 −11 mol m −2 s −1 , with a pH ranging from 2 to 8.5.…”

Section: Phosphorus Acid-solubilization Mechanismmentioning

confidence: 99%

Bioavailable atmospheric phosphorous supply to the global ocean: a 3-D global modeling study

et al. 2016

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Abstract. The atmospheric cycle of phosphorus (P) is parameterized here in a state-of-the-art global 3-D chemistry transport model, taking into account primary emissions of total P (TP) and soluble P (DP) associated with mineral dust, combustion particles from natural and anthropogenic sources, bioaerosols, sea spray and volcanic aerosols. For the present day, global TP emissions are calculated to be roughly 1.33 Tg-P yr−1, with the mineral sources contributing more than 80 % to these emissions. The P solubilization from mineral dust under acidic atmospheric conditions is also parameterized in the model and is calculated to contribute about one-third (0.14 Tg-P yr−1) of the global DP atmospheric source. To our knowledge, a unique aspect of our global study is the explicit modeling of the evolution of phosphorus speciation in the atmosphere. The simulated present-day global annual DP deposition flux is 0.45 Tg-P yr−1 (about 40 % over oceans), showing a strong spatial and temporal variability. Present-day simulations of atmospheric P aerosol concentrations and deposition fluxes are satisfactory compared with available observations, indicating however an underestimate of about 70 % on current knowledge of the sources that drive the P atmospheric cycle. Sensitivity simulations using preindustrial (year 1850) anthropogenic and biomass burning emission scenarios showed a present-day increase of 75 % in the P solubilization flux from mineral dust, i.e., the rate at which P is converted into soluble forms, compared to preindustrial times, due to increasing atmospheric acidity over the last 150 years. Future reductions in air pollutants due to the implementation of air-quality regulations are expected to decrease the P solubilization flux from mineral dust by about 30 % in the year 2100 compared to the present day. Considering, however, that all the P contained in bioaerosols is readily available for uptake by marine organisms, and also accounting for all other DP sources, a total bioavailable P flux of about 0.17 Tg-P yr−1 to the oceans is derived. Our calculations further show that in some regions more than half of the bioavailable P deposition flux to the ocean can originate from biological particles, while this contribution is found to maximize in summer when atmospheric deposition impact on the marine ecosystem is the highest due to ocean stratification. Thus, according to this global study, a largely unknown but potentially important role of terrestrial bioaerosols as suppliers of bioavailable P to the global ocean is also revealed. Overall, this work provides new insights to the atmospheric P cycle by demonstrating that biological materials are important carriers of bioavailable P, with very important implications for past and future responses of marine ecosystems to global change.

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Section: Phosphorus Acid-solubilization Mechanismmentioning

confidence: 99%

Bioavailable atmospheric phosphorous supply to the global ocean: a 3-D global modeling study

et al. 2016

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“…on the hydroxyapatite was studied using the pH from 7 to 11. The composition of the surface phase of hydroxyapatite is constant in solution of pH in the range 4-10 ( Bengston et al 2009). Since hydroxyapatite is Adsorption (2016) 22:697-706 701 the salt of slight acid, it could run over two-step hydrolysis in an aqueous solution on the hydroxyapatite surface.…”

Section: Adsorption Of Sr 21 Ionsmentioning

confidence: 99%

Study of sorption processes of strontium on the synthetic hydroxyapatite

Janusz

Skwarek

2016

Adsorption

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Adsorption of 90 Sr on hydroxyapatite is important in many fields of life. The aim of the paper was to discuss the changes in the double electrical layer at the hydroxyapatite/electrolyte solution interface during Sr ions adsorption and to establish the relations between time and adsorption on this material. Hydroxyapatite was prepared by the wet method, characterized by the X-ray diffraction and accelerated surface area and porosimetry methods. Studies of adsorption were carried out using 90 Sr isotopes and ionic solutions containing this ion depending on concentration and pH of the solution. Sr adsorption isotherms on hydroxyapatite were determined and the effect of strontium ions presence on the surface charge density and zeta potential was discussed.

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“…The surface ion composition (and hence the surface charge) of HAp in aqueous medium varies according to the ion composition of the medium, and HAp surfaces show negative charges in aqueous media under neutral pH 41) . The deviation of the Ca/P ratio from the stoichiometric value (Ca/P molar ratio=10/6) would also result in a decrease in the negative surface charge on the HAp surface in an aqueous medium 42) due to an increase in the solubility of HAp 41) and the degree of re-adsorption of PO4 3− ions onto the HAp surface 43) . In this study, the CPC adsorption onto the HAp nanoparticles with different morphologies showed a Langmuir-type adsorption.…”

Section: Discussionmentioning

confidence: 99%

Adsorption and desorption behaviors of cetylpyridinium chloride on hydroxyapatite nanoparticles with different morphologies

et al. 2016

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Application of hydroxyapatite (HAp) nanoparticles to repair damaged enamel has attracted recent attention. In this study, HAp nanoparticles with various morphologies (spherical, short-rod, long-rod and fiber morphologies) were synthesized via chemical precipitation methods without the addition of template molecules, and the adsorption/desorption behaviors of a cationic antibacterial agent, cetylpyridinium chloride (CPC), on the HAp nanoparticles were evaluated. The adsorption of CPC on each HAp nanoparticle showed Langmuir-type adsorption, and the short-rod/long-rod HAp nanoparticles showed thermodynamically more stable adsorption of CPC than that with the spherical/fiber HAp nanoparticles. The desorption rate of CPC from the short-rod/long-rod HAp nanoparticles was slower than that of the spherical/fiber HAp nanoparticles. The HAp nanoparticles with different CPC release profiles presented here have potential applications as nanoparticulate enamel repair agents with antibacterial properties.

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A solubility and surface complexation study of a non-stoichiometric hydroxyapatite

Cited by 93 publications

References 41 publications

Bioavailable atmospheric phosphorous supply to the global ocean: a 3-D global modeling study

Bioavailable atmospheric phosphorous supply to the global ocean: a 3-D global modeling study

Study of sorption processes of strontium on the synthetic hydroxyapatite

Adsorption and desorption behaviors of cetylpyridinium chloride on hydroxyapatite nanoparticles with different morphologies

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