Beta tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) mixed with gypsum (CaSO₄·2H₂O) was heated at 1300°C and 1400°C. The resulting products were characterized by DTA, XRD, FTIR, EDX and hydration reactivity. An inhibition effect on the transition of the low temperature form β to high temperature form α was observed with increasing the amount of gypsum. The substitution of SO₄ for PO₄ was suggested from increases of the β→α transition temperature and hydration reactivity. However both the substitution and the presence of S were not recognized by XRD, EDX and FTIR. Increasing the amount of gypsum resulted in the formation of hydroxyapatite (Ca₅(OH)(PO₄)₃) at 1300°C and tetracalcium phosphate (Ca₄(PO₄)₂O) at 1400°C. The hydration reactivity was in the order, pure α-TCP << α-TCP heated with gypsum.

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Phosphonylation of catechin (CA) has been achieved using inorganic diphosphonate (DP) in aqueous solution. The optimum condition for the phosphonylation of catechin with DP is CA : DP = 1 : 10, pH 6 and 25 °C. 3'-Phosphonylcatechin and 4'-phosphonylcatechin were synthesized with the total yield of more than 25 %. The phosphonylated products of CA were stable at 10 °C and pH 3. The reaction mechanism of CA with DP was discussed.

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The effect of β-calcium orthophosphate (β-Ca₃(PO₄)₂:β-TCP) addition (1 ∼ 20 mass%) on the high-temperature plastic deformation of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂:HAp) ceramic specimen was examined. The high-density HAp ceramic body with β-TCP addition, which was composed of submicrometer-sized grains, was fabricated by pulse-current pressure firing at a temperature between 900 and 1050°C for 10 min under a pressure of 50 MPa. The relative densities of HAp ceramics with 1 to 20 mass% β-TCP addition fabricated by pulse-current pressure firing at 1000°C for 10 min exceeded 99%; the grain sizes increased from 0.2 to 0.3 μm with increasing β-TCP addition from 0 to 10 mass% and then steeply to 0.9 μm with increasing β-TCP addition from 10 to 20 mass%. The tensile strain of the HAp specimen with 1 mass% β-TCP addition pulse-current pressure fired at 1000°C for 10 min achieved a maximum of 390% for a test temperature of 1000°C and a strain rate of 1.48 × 10^-4 s^-1, compared to 364% for the monolithic HAp specimen.

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The work presented in this paper deals with the determination of optimum parameters during the partial acidulation of the phosphate ore of Djebel Onk (Algeria) and the determination of P₂O₅ water-soluble. The first part is devoted to P₂O₅ conversion rate during partial acidulation of phosphate with different particle sizes (80 μm, 160 μm and 250 μm). These conversion rates are obtained by performing a series of reactions between phosphate and sulfuric acid diluted from 10 to 50 wt% and with reaction times ranging from 10 to 50 minutes. The best conversion rate (38.78%) was obtained at a reaction time of 50 minutes with phosphate particle size of 80 μm and an acid concentration of 50 wt%. The second part, concerns the measurement of P₂O₅water-soluble of phosphate partially acidulated (PAPRs) with 40% and 50 wt% sulfuric acid. The percentage of P₂O₅ soluble in water has reached 14.98% for PAPRs obtained with phosphate particle size of 80 μm and an acid of 50 wt%.

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The elution behaviors of phosphate from the slag released by a chemical factory using various eluates were examined. Since this slag was covered with organic species, two pretreatment methods for the slag - one the calcination of the slag and the other the trituration of the slag - were employed to strip away the organic species from the slag. Since the elution rate from the pre-triturated slag was evidently greater than that from the pre-calcined slag, the elution behavior of the former was mainly examined in the present study. For the efficient elution of phosphate from the slag, the use of 1M HNO₃ as an eluate and 30 min of trituration time were suitable. Unfortunately, together with the elution of phosphate from the slag, some cationic species were simultaneously eluted. In the present study, the removal behavior of iron cation, which was a main contaminant in the slag, using calcium hydroxyapatite (CaHAp) was also examined. Even when the solution obtained by the elution of the slag was employed for the removal of Fe³⁺ using CaHAp, the Fe³⁺ could be favorably removed from the solution. Results from the present study suggests that unused phosphate in slag is a potential source of raw material for rare phosphorus.

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Iron phosphate was prepared from iron nitrate and phosphoric acid with sodium dodecyl-sulfate at various stirring hours. The chemical composition of the obtained samples was estimated from ICP and XRD measurements. Particle shape and size distribution were observed by SEM images and laser diffraction / scattering methods. Further, the catalytic activity was studied with the decomposition of the complex between hormaldehyde and acetylacetone. Samples heated at 600°C indicated XRD peaks of FePO₄. Iron phosphates heated at 200 and 400°C works as a catalyst.

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Nanosized Ag₃PO₄ particles were successfully synthesized by a facile solution method. The photocatalytic activity for organic dye degradation strongly related to the particle size of the Ag₃PO₄ particles. Nanosized Ag₃PO₄ particles showed higher photocatalytic activity for degradation of RhB dye than those of normal size Ag₃PO₄ particles and titania based photocatalysts.

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The effects of potassium peroxodisulfate (K₂S₂O₈) on the formation of calcium phosphate particles produced by aging Ca(OH)₂ and sodium triphosphate (sodium tripolyphosphate, Natpp: Na₅P₃O₁₀) mixed solution at 100∼160°C for 18 h were examined. Spherical and monodispersed particles were produced at low K₂S₂O₈ concentration ([K₂S₂O₈]) region ([K₂S₂O₈]≤4 mM) and their size was increased by increase in [K₂S₂O₈]. On the contrary, fine irregular particles were produced at [K₂S₂O₈]≥6 mM. The monodispersed spherical particles produced at [K₂S₂O₈]≤4 mM were amorphous, though small irregular particles produced at [K₂S₂O₈]≥6 mM were poorly crystallized calcium pyrophosphates (β-Ca₂P₂O₇). The Ca/P atomic ratios of these samples were 0.79∼0.90, fairly closed to the Ca/P atomic ratio of 1.0 for β-Ca₂P₂O₇. A high adsorption selectivity of H₂O was observed on amorphous monodispersed spherical particles. On the other hand, the β-Ca₂P₂O₇ particles with small amounts of hydrated H₂O produced at [K₂S₂O₈]≥6 mM exhibited no selective adsorption of H₂O. With increase in the aging temperature, small numbers of transparent balloon-like hollow spheres were obtained at 120∼140°C. However, the fraction of hollow spheres was less than 5%. Aging above 150°C, no balloon-like hollow sphere was precipitated but finally calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, Hap) particles with small rod-like shape could be precipitated. These Hap particles produced at 150 and 160°C did not exhibit selective adsorption of H₂O.

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B-type carbonate apatite (CA) substituting for phosphate ions, is the major inorganic components of vertebrate bones. CA is more biodegradable than HA and has been expected as a next generation biomaterial. We had reported that the polarized HA could promote bone healing. The purpose of this study was to investigate the effects of the electrically polarization on CA characterization. CA synthesized by wet method was sintered at various temperatures in carbon dioxide atmosphere. The TG measurement and polarization treatment of the sintered CA were performed. From the results of XRD and FT-IR analyses, CA was inclusion of contain carbonate about 5wt%. From TSDC measurement, the quantity of accumulated charges of CA was larger than HA. In addition, we evaluated the osteoclast behaviors on non-polarized CA and polarized CA. From the observation of cell morphology, there were multinucleated cells having actin ring structures specific for the activated osteoclasts on the CA surfaces.

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