The preparation of hydroxyapatite from unrefined calcite residues and its application for lead removal from aqueous solutions.

ABSTRACT: Calcite originating from waste treatment technologies was utilised for the chemical precipitation of hydroxyapatite (HAP). The physicochemical properties of the as-synthesised-HAP was fully characterised using FT-IR, BET, SEM and TEM, confirming its crystal structure and formation of high purity HAP by XRD. The product was employed for removal of lead from aqueous media at pH 5.0, achieving almost 80% of the adsorption in the first 5 min and a maximum adsorption capacity for Pb²⁺ of 224.4 mg g^-1. A contact time of 40 min was required to achieve equilibrium with Pb²⁺ uptake of 98%. The kinetics of the cation exchange of HAP from calcite were predicted using integrated rate laws, revealing a pseudo-second order cation exchange process with a rate constant of

SUBMITTER: Bernalte E 

PROVIDER: S-EPMC9060579 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature