Preparation of calcium phosphates from artificial phosphorus wastewater and sea urchin shells

Calcium phosphates were prepared from sea urchin shells and artificial phosphorus waste fluid. The calcined shells were dissolved in hydrochloric acid solution, and then filtered. This sea urchin shell extract was mixed with the artificial phosphorus waste fluid prepared from sodium dihydrogen phosphate. It was then adjusted to pH 7 using sodium hydroxide solution. The obtained precipitate contained the organic coloring material from sea urchin shell calcined at lower temperature. The main component of the precipitate was CaHPO 4 •2H 2 O. This phosphate was changed to Ca 2 P 2 O 7 by heating because of the condensation reaction. The chemical composition, particle shape, and size were not strongly affected by the heating temperature for the pretreatment.