Sorption of tartrate ions to lanthanum (III)-modified calcium fluor- and hydroxyapatite

The present article details the formation of lanthanum-modified apatites and the binding process of tartrate ions with these obtained apatites. Chemical analyses, FT-IR and 31P NMR spectroscopies, XRD powder, TGA, and TEM analyses were employed for studying the reaction between Ca10(PO4)6(OH)2 (HAp) or Ca10(PO4)6(F)2 (FAp) and LaCl3. The reaction was found to take place mainly through partial dissolution of the apatite followed by precipitation of a new phase containing lanthanum phosphate. When La3+ was introduced in the presence of L(+)-tartaric acid (TAH2), no fundamental changes were observed in the HAp or FAp structures. However, there did occur a formation of a new phase of Ca or/and La tartrate salt.

Partial dissolution of Ca10(PO4)6(OH)2 (HAp) or Ca10(PO4)6F2 (FAp) in presence of LaCl3 leads to the formation of a new LaPO4 microcrystalline phase without incorporation of La3+ in the apatite structure. The TEM micrograph for HAp is on the left and for sample after treatment with LaCl3 on the right.Figure optionsDownload as PowerPoint slide