Uptake of a Few Divalent Heavy Metal Ionic Species by a Fixed Bed of Hydroxyapatite Particles

Abstract

Breakthrough curves were measured for Cd²⁺, Cu²⁺ and Pb²⁺ in their single, binary and ternary nitrate aqueous solution systems using a fixed bed of hydroxyapatite particles in order to obtain volumetric mass transfer coefficients. Breakthrough curves for Pb²⁺ showed particular profiles depending on the pH of influent solutions in the bed. For the binary and ternary systems containing Pb²⁺, the curves for each ion showed that Pb²⁺ displaced not only calcium but also other co-existent ions which were already collected in the substrate. It was considered that Cd²⁺ and Cu²⁺ were collected in the vicinity of the internal surface of particles, but the uptake of Pb²⁺ occurred in the interior as well as at the internal surface of hydroxyapatite particles.