Synthesis of nano-crystalline hydroxyapatite and ammonium sulfate from phosphogypsum waste

Synthesis and Characterization of Hydroxyapatite Using Ammonium Hydroxide and Ethylenediaminetetraacetic Acid

“…The HAp crystal composition was analyzed based on the Ca and P signals observed in the EPMA, which yielded a Ca/P ratio of 1.62. This obtained value is close to the Ca/P ratio (1.67) and is found in the human bone . EPMA shows also that HAp contains a tiny amount of sodium because we used Na‐EDTA during synthesis.…”

“…The results revealed that the HAp was predominantly composed of calcium (Ca) and phosphorous (P) as shown in Table . EDX data showed that the Ca/P ratio was approximately 1.66, which was almost close to the stoichiometric ratio (1.67) that was expected for a pure HAp phase …”

“…This obtained value is close to the Ca/P ratio (1.67) and is found in the human bone. 33 EPMA shows also that HAp contains a tiny amount of sodium because we used Na-EDTA during synthesis.…”

Synthesis of rod-like hydroxyapatite with high surface area and pore volume from eggshells for effective adsorption of aqueous Pb(II)

“…Removal of heavy metals from drinking and wastewaters is, therefore, vital for human health and economic point of view. Hydroxyapatite (HAp) has been applied in this regards [4][5][6]; however, because of economic implications, alternative procedures to produce HAp from cheap and recyclable or waste materials have been pursued [7][8][9][10]. The use of waste eggshells has been dominant [4,11] among the alternative procedures because of the fact that it is cheap and readily available.…”

Use of tendon to produce decellularized sheets of mineralized collagen fibrils for bone tissue repair and regeneration

“…EDX analysis of the scaffolds indicated a Ca/P molar ratio of 1.46, close to known Ca/P molar ratios for various forms of calcium phosphates: 1.33 for octacalcium phosphate, 1.5 for amorphous calcium phosphate and calcium deficient HA, 1.67 for precipitated HA, 1.8 for Na and carbonate containing apatite and 2.0 for heavily carbonated HA (Driessens et al, ). For human bone, Ca/P molar ratios typically range from 1.19 to 2.28 (Fountos et al, ; Mousa & Hanna, ; Tzaphlidou & Zaichick, ).…”