2.1.2. Determination of the solubility product Ksp for CaClH2PO4H2O
The solubility product (Ksp) for CaClH2PO4H2O was determined
by measuring its solubility. The CaClH2PO4H2O crystals were
produced in an artificial system by mixing CaCl2 solution and
H3PO4 solution with a molar ratio of 1:1. The produced crystals
have been identified with powder X-ray diffraction (XRD) [25]. The
crystals were added into distilled water step-wise in a
flat bottom
double-wall reactor until a suspension was formed. Then the
suspension was kept under stirring with a magnetic stirrer at 298 K
overnight. The reactor was sealed with a rubber plug to avoid water
evaporation during stirring. The temperature of the solution was
controlled through an external thermostat. Two batches were
running at the same time. Insoluble particles were removed by
filtration (0.5 mm). The pH of the clear solution was determined
and the concentrations of PO4
3 and Cl were measured with ionexchange
chromatography (IC).