Synthesis, thermal stability and hydrothermal transformation of one of the urinary tract stones; struvite (MgNH4PO4·6H2O)

Struvite (MgNH
4
PO
4
·6H
2
O, magnesium ammonium phosphate hexahydrate) is one of the urinary tract stones seen in humans and animals. Moreover, this phase is frequently encountered in the waste water treatment and purification plants. Struvite powders were easily synthesized, without any pH control precautions, in this study and the powders heated in an air atmosphere were observed to lose their crystal structure. This amorphous but struvite-related substance was found to crystallize itself back into struvite at room temperature when soaked in ammonium ion-containing aqueous solutions. Struvite powders were also found to transform, at 36.5°C and in 72 hours, into the human bone mineral, when immersed in solutions having similar alkali (Na and K) and alkaline earth (Ca) ions such as those of body fluids. As-synthesized and transformed powders were analyzed with X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy.