Table 7.

Properties of HA from biogenic sources

No.	Source	Ca/P ratio	Particle size (nm)	Morphology	Secondary phase	Calcination (T/°C)
1	Egg shell	1.65	—	—	β-TCP	900 [91]
2	Coral shells	—	—	—	—	— [91]
3	HCl+DAHP solution treated Egg shells	1.67	50	Rectangular	—	[92]
4	Hen Egg shells	>1.67	18	Spherulite	—	800-1200 [93]
5	Chicken Egg shell	—	~35	Prolate spheroidal	—	700 [94]
6	Hen Egg shell	1.63	—	—	—	[95]
7	Egg shells treated with *DAHP+EDTA		78	Flower like	—	[116]
8	Egg shell treated by precipitation technique	1.67	~35	Globule like	—	900 [96]
9	Oyster shell		—	Rod like	—	1000 [97]
10	Ground waste egg shell			Flower like	—	— [98]
11	Fruits and egg shell waste	1.57–1.77	12-49	Needle like and rod like	—	— [99]
12	Egg shell waste	2.20	—	Spheroidal	β-TCP	1100 [105]
13	Mussel shell	1.61	—	—	—	— [100]
14	Egg shell	—	—	—	—	600 [101]
15	Egg shell	—	15 k-35 k	Flower like	—	— [102]
16	Sea urchin shell	—	—	Rod like	—	900 [103]
17	Egg shell	–	60	Whiskers	CaHPO4	700 [104]

* DAHP = ‘2,4-diamino-6-hydroxypyrimidine and EDTA = ethylenediaminetetraacetic acid’