ปิยะพงษ์ ปานแก้ว. Synthesis and Characterization of Calcium Phosphate Prepared from Chicken Eggshells. Doctoral Degree(Physics). King Mongkut's University of Technology Thonburi. KMUTT Library. : King Mongkut's University of Technology Thonburi, 2011.
Synthesis and Characterization of Calcium Phosphate Prepared from Chicken Eggshells
Abstract:
Nowaday, biphasic calcium phosphate (BCP) has been extensively studied for
biomedical applications. BCP consists of hydroxyapatite [HAp, Ca10(P04)6(OHh)2)] and
Beta-tricalcium phosphate [Beta-TCP, Ca3(P04)2], therefore it has been widely used for
bioactivity and resorbability properties. In this work, CaO powders were prepared from
the eggshells by heating at 1300 C for 4 h. CaO powders were mixed with HN03 to
obtain Ca(N03)2 solution. In the first experiment, each of Ca(N03)2 and (Nh4)2HP04
solutions was mixed with NH4OH solution to obtain a pH of 7.6. Then, (NH4)2HP04
solution was dropped into Ca(N03)2 solution with different rates of 13, 5 and 3 ml/min,
respectively. The second experiment, both Ca(N03)2 and (NH4)2HP04 solutions were
added with NH4OH solution to obtain different pH values of 8.6, 9.6 and 10.6,
respectively. Then, (NH4)2HP04 and Ca(N03)2 solutions with the same pH was mixed
by dropping (NH4)2HP04 into Ca(N03)2 solutions at a rate of 3 ml/min. The mixed
solutions, obtained from the first and second experiments, were allowed to precipitate
for 8 h, filtered and dried at 80 C for 24 h. Finally, Cal0-x(HP04)x(P04)6-x(OH)2-x
(Ca-dHAp) powders were obtained. The Ca-dHAp powders were further calcined at
different temperatures of 200-1200 C for 3 h. Then BCP powders of the formula
(l-X)Ca10(P04)6(OH)2 /3xCa3(P04)2 were obtained.
For the prepared BCP powder samples, the phase fractions of Beta-TCP in BCP were
determined from X-ray diffraction patterns (XRD) and Rietveld refinement method. The
morphology and particle size of BCP powders were determined by scanning electron
microscopy (SEM) and Atomic force microscopy (AFM). For the solution with a
constant pH value of 7.6, the phase fractions of P-TCP in BCP was found to be 61, 52,
45 wt% for addition rate of 13, 5 and 3 mllmin, respectively. For the solution with a
constant rate of 3 mllmin and pH values of 8.6, 9.6 and 10.6, the phase fractions of
Beta-TCP in BCP was found to be 42, 38 and 28 wt%, respectively. The particle size of
BCP powders was found to be 35-46, 41-52 and 55-64 for addition rate of 13, 5 and 3
ml/min, respectively. The particle size of BCP powders was found to be 55-70, 60-79
and 76-93 nm for pH values of 8.6, 9.6 and 10.6, respectively. It is found that the
maximum Beta-TCP phase in BCP was obtained from an addition rate of 13 ml/min and a
pH value of 8.6 with BCP particle sizes of 35-46 and 55-70, respectively.