Electroflotation of precipitated phosphate from synthetic solution

X-ray diffraction and particle size measurements indicated that the precipitates were a mixture of hydroxyapatite and calcium-deficient hydroxyapatite, with size ranging from 3 to 10 μm. Electroflotation with Na-oleate as surfactant was used to recover the precipitates.

The surfactant adsorption was evaluated through zeta potential measurements. The influence of Na-oleate concentration, pH and bubble size on phosphate recovery was investigated. In the absence of Na-oleate, a phosphate recovery of 50% was achieved, while in the presence of 20 mg L-1 of Na-oleate it was increased to 90%, at pH 11.