Phosphate recovery through adsorption assisted precipitation using novel precipitation material developed from building waste: Behavior and mechanism

Phosphate is very important basic material in agricultural and other industrial applications. In present study, phosphate was precipitated and recovered through a tablet precipitation material (TPM) which was developed from solid building waste. The development of TPM provided an alternative for the management of building waste. The results showed that TPM could effectively recover phosphate from aqueous solution; the final precipitates were consisted of hydroxyapatite and brushite. The precipitation recovery process was assisted and drove by adsorption mechanism. The adsorption process concentrated and attracted phosphate that supplied partial phosphate supersaturation surround the surface of TPM and assisted the precipitation process. The equilibrium of removal and recover process could be attained in 60 min. The maximum recovery capacity achieved 3.81 ± 0.24 mg g^-1. In addition, the release of Ca²⁺ from TPM fitted a pseudo-2nd order model, and the release process was divided into two stages according to the Fick's law. Totally, TPM developed from building waste exhibited sufficient potential in phosphate recovery.