Geoscience Reference
In-Depth Information
iii. restricted citric acid/Ca molar ratio (1.2
1.31),
iv. higher temperature (180
C) and longer duration (2.75 h at 200
C),
v. final pH of 3.4
3.8.
Lactic acid
H
3
PO
4
Ca(OH)
2
(Ca-lactic complexes, no precipitate)
Homogeneous solution
Hydrothermal treatment
(200ºC, 5
h, 2
MPa)
Suction filtration, washing, drying
HAp whiskers
(Ca/P = 1.59
−
1.62)
XRD, SEM, IR, Raman
determination of Ca/P ratio
HAp whiskers
(Ca/P = 1.61)
CaCO
3
(35
−
70
wt%)
Mixing in NH
3
OH solution
(2
h, pH = 11)
Homogeneous
mixture
Reaction
at 600ºC (1
−
72
h)
Dissolution of CaCO
3
, CaO
in 0.2
M triammonium citrate solution
(pH = 8, 24
h)
HAp whiskers
(Ca/P = 1.64
−
1.67)
XRD, SEM, IR, Raman
determination of Ca/P ratio
Figure 10.68 Steps involved in the experimental procedure for the preparation of HAp
[335]
.