The pyrolytic synthesis of calcium phosphate compounds from carbonized fowl droppings

We succeeded in producing biomimetic calcium phosphate compounds, β-tricalcium phosphate (β-TCP: Ca3[PO4]2) or biphasic calcium phosphate of two-phase ceramics (BCP) with hydroxyapatite (HAp: Ca10[PO4]6[OH]2) and β-TCP, from carbonized fowl droppings via one-pot hydrothermal reactions. It occurred to us to use the residue, mineral traces and organic compounds in fowl droppings obtained by carbonization as control reagents for the synthesis reaction. Through this selective generation of the single-phase Mg-doped β-TCP, a stratified formation that resembled a natural nacreous layer was achieved. Further, we were able to produce only HAp/32.4% β-TCP possessing comparatively high mechanical strength in two-phase BCP ceramics by using incinerated fowl droppings prepared from carbonized fowl droppings sintered in air at 800 °C. In the adsorption of ammonia gas, biomimetic calcium phosphate compounds synthesized from fowl droppings have comparable loading capacities to activated carbon.

Graphical abstractThe Mg-doped β-TCP or BCP with hydroxyapatite and β-TCP was synthesized from carbonized fowl droppings via one-pot hydrothermal reactions. Abundant　minerals and trace amounts of low molecular weight organic compounds that remains in carbonized fowl droppings act as control reagents for a stratified formation of　β-TCP or BCP.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The synthesis of the calcium phosphates using carbonized fowl droppings. ► Selective synthetic method of β-tricalcium phosphate and biphasic calcium phosphate. ► A stratified formation that resembled a natural nacreous layer was achieved. ► High NH3 gas adsorption capabilities of the synthesized compounds were recognized.