Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

Table 1 Summary of synthesis and composition of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb_xCa_1−x)₅(PO₄)₃OH]

Sample No.	Volumes of the precursors (mL)				Solid composition	Residual solid composition after dissolution at 25 °C and an initial pH of 2.00 for 300 days
	0.4 M	0.4 M	4.4 M	0.12 M
	Pb(CH₃COO)₂·2H₂O	Ca(CH₃COO)₂·H₂O	CH₃COONH₄	NH₄H₂PO₄
Pb–Ca-HAP-00	0	250	250	500	(Pb_0.00Ca_1.00)₅(PO₄)₃OH	(Pb_0.00Ca_1.00)₅(PO₄)₃OH
Pb–Ca-HAP-01	25	225	250	500	(Pb_0.10Ca_0.90)₅(PO₄)₃OH	(Pb_0.10Ca_0.90)₅(PO₄)₃OH
Pb–Ca-HAP-02	50	200	250	500	(Pb_0.20Ca_0.80)₅(PO₄)₃OH	(Pb_0.21Ca_0.79)₅(PO₄)₃OH
Pb–Ca-HAP-03	75	175	250	500	(Pb_0.30Ca_0.70)₅(PO₄)₃OH	(Pb_0.32Ca_0.68)₅(PO₄)₃OH
Pb–Ca-HAP-04	100	150	250	500	(Pb_0.41Ca_0.59)₅(PO₄)₃OH	(Pb_0.44Ca_0.56)₅(PO₄)₃OH
Pb–Ca-HAP-05	125	125	250	500	(Pb_0.51Ca_0.49)₅(PO₄)₃OH	(Pb_0.54Ca_0.46)₅(PO₄)₃OH
Pb–Ca-HAP-06	150	100	250	500	(Pb_0.61Ca_0.39)₅(PO₄)₃OH	(Pb_0.66Ca_0.34)₅(PO₄)₃OH
Pb–Ca-HAP-07	175	75	250	500	(Pb_0.69Ca_0.31)₅(PO₄)₃OH	(Pb_0.77Ca_0.23)₅(PO₄)₃OH
Pb–Ca-HAP-08	200	50	250	500	(Pb_0.80Ca_0.20)₅(PO₄)₃OH	(Pb_0.88Ca_0.12)₅(PO₄)₃OH
Pb–Ca-HAP-09	225	25	250	500	(Pb_0.89Ca_0.11)₅(PO₄)₃OH	(Pb_0.95Ca_0.05)₅(PO₄)₃OH
Pb–Ca-HAP-10	250	0	250	500	(Pb_1.00Ca_0.00)₅(PO₄)₃OH	(Pb_1.00Ca_0.00)₅(PO₄)₃OH

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