On precipitated calcium and magnesium phosphates during synthetic hard waters softening by monosodium phosphate

Phosphates were largely used to soften process or drinking waters. We have investigated the precipitation of Ca2+ and Mg2+ ions by monosodium phosphate dehydrate. Magnesium phosphate starts precipitating at pH(0) = 8.6. The obtained solids have been identified by chemistry analyses, FTIR spectroscopy, X-ray diffraction, thermo gravimetric analysis and differential thermal analysis. The solid phases obtained vary with pH0. It shows that DCPD (dicalcium phosphate dehydrate, CaHPO4 center dot 2H(2)O) precipitated within pH0 5 to 6.6, the TCP (tricalcic phosphate) and other apatite appear below pH(0) = 7. The DCPD (dicalcium phosphate dihydrate, CaHPO4 center dot 2H(2)O,) precipitated was a pure product that can be used in nanotechnology and biomedical technology. We are presently testing these solids for natural waters defluoridation.