Calcium Phosphate Powder Synthesized from Calcium Acetate and Ammonium Hydrophosphate for Bioceramics Application

Abstract

Calcium phosphate powder was synthesized at room temperature from aqueous solutions of ammonium hydrophosphate and calcium acetate without pH adjusting at constant Ca/P molar ratio 1.5. Phase composition of the as-synthesized powder depended on the precursors concentration: At 2.0 M of calcium acetate in the starting solution, poorly crystallized hydroxyapatite was formed, 0.125 M solution of calcium acetate afforded brushite, and the powders synthesized from 0.25-1.0 M calcium acetate solutions were mixtures of the mentioned phases. Firing at 1100 • C led to complete elimination of the reaction by-products, yet the phase composition of the annealed compacted samples was the following: When 2.0 M solution of calcium acetate was used, the obtained ceramics consisted of β-Ca 3 (PO 4 ) 2 , whereas at 0.125 to 1.0 M of calcium acetate, the ceramics was a mixture of β-Ca 3 (PO 4 ) 2 and β-Ca 2 P 2 O 7 . Synthesized calcium phosphate powders can be used as the powdered precursors for biocompatible bioresorbable composite ceramics production.

Chemical composition of organic acid digest from a municipal wastewater treatment plant and chemical modeling of nuisance struvite formation and phosphorus recovery as brushite

“…Further additions of calcium hydroxide to the titrated organic acid digest filtrate beyond the point of precipitating 90% of soluble P are predicted to form calcium carbonate as calcite upon reacting with dissolved carbon dioxide. The hypothesis that brushite might indeed form upon titration of organic acid digest and filtrate is bolstered by consideration of some of the methods of synthesizing brushite under laboratory conditions, such as ammoniation of calcium phosphate solutions [24], the titration of monoammonium phosphate with ammoniated calcium hydroxide [25], and titration of diammonium phosphate with calcium acetate [26]. Furthermore,…”

Powder Mixture for the Production of Microporous Ceramics Based on Hydroxyapatite

“…After heat treatment at 200 • C, according to XRD data (Figure 5, Table 1), the following phases were detected in the powder mixture: CaHPO (2). The form of the XRD curve (Figure 5) indicates that a remarkable part of the powder mixture under investigation presents in quasi-amorphous form after heat treatment at 200 • C. tions ( 8), ( 9) and (10), describing the transformation of hydrated tricalc Ca3(PO4)2 xH2O (as it was described in PDF card or Ca-deficien Ca9(HPO4)(PO4)5(OH) relative to -tricalcium phosphate -Ca3(PO4)2, wh the 650-800 °C interval [38,39]. The phase composition of ceramics after firing at 1100 °C (Ca10(PO4)6(OH)2) and a small quantity of -tricalcium phosphate -Ca3(P phase composition of ceramics after firing at 1200 °C inclu (Ca10(PO4)6(OH)2) only.…”

“…The phase composition of ceramics after firing at 1000 • C included HA (Ca 10 (PO 4 ) 6 (OH) 2 ), β-tricalcium phosphate β-Ca 3 (PO 4 ) 2, and a small quantity of calcite CaCO 3 . The presence of β-tricalcium phosphate β-Ca 3 (PO 4 ) 2 after firing at 1000 • C can be explained with the possibility of reaction (6) in the 550-770 • C interval and reactions (8), ( 9) and (10), describing the transformation of hydrated tricalcium phosphates Ca 3 (PO 4 ) 2 xH 2 O (as it was described in PDF card or Ca-deficient hydroxyapatite Ca 9 (HPO 4 )(PO 4 ) 5 (OH) relative to β-tricalcium phosphate β-Ca 3 (PO 4 ) 2 , which is possible in the 650-800 • C interval [38,39].…”

Synthesis of Hydroxyapatite Nanoparticles Using Eggshells and Two Different Phosphate Sources

“…Numerous methods are applied in the synthesis of Hydroxyapatite nanoparticles, including solidstate, acid-base, precipitation, sol-gel, hydrothermal, mechanochemical, plasma techniques, layer hydrolysis of calcium phosphate combustion, and other wet chemistry methods [3], [5], [21]. Wet chemistry and precipitation are extensively employed in the production of HAP powders due to their cost-effectiveness, straightforward methodology, and ability to precisely control particle size, morphology, and chemical composition [1], [26].…”