Sorption of bismuth(iii) and its chloride complexes with 2-aminopyrimidine cation on hydroxyapatite of various textures

Specific features of the interaction between bismuth(iii) and hydroxyapatite (HAP) of various morphologies during its sorption and co-crystallization binding were revealed. The obtained sorption isotherms nearly coincide with each other regardless of the HAP type used and cannot be described in terms of the Langmuir or Freundlich models. Bismuth can form the intrinsic phase of bismuth phosphate due to the chemical or topochemical reaction with HAP when the sorption method is used. In the case of co-crystallization binding of bismuth ions, the morphological modification of HAP occurs. The bismuth complexes with aminopyrimidine in neutral and weakly acidic solutions are readily hydrolyzed to form a precipitate, and no binding with HAP occurs.