Investigation of sorption of lead ion from simulated body fluid solution by nanocrystalline Ca-deficient carbonated hydroxyapatite

Abstract

The aim of the paper was investigation of sorption process of nanocrystalline calcium-deficient
carbonated hydroxyapatite (CHA) for heavy metal ions on the example of Pb2+. Sorption of Pb2+ ions was
investigated in simulated body fluid solution at pH 5.5 (bone resorption) and pH 7.4 (bone formation). The
prepared samples CHA were characterized using scanning electron microscopy (SEM), method BrunauerEmmett-Teller
(BET), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Total
concentration Pb2+ in the clear separated supernatant was determined by inversion voltammetry method. The
maximum Pb2+ sorption capacities of these samples CHA were determined, using a linearized Langmuir
model applied to batch sorption data collected at time of 48 h. XRD and FT-IR were used to identify the
materials present in the solid phase after sorption.
The synthesized CHA showed an excellent sorption capacity for Pb2+ ions. The maximum Pb2+
sorption capacities of CHA from model solution at pH 5.5 add up to 588 mg/g, from model solution at pH 7.4
Доан Ван Дат и др. / Сорбционные и хроматографические процессы. 2015. Т. 15. Вып. 2
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add up to 1724 mg/g. Examination of solid phase after sorption indicated that a new crystalline phase of
hydroxylpyromorphite was formed in the sorption process. The character of changing the significance and
sign of zeta-potential of the synthesized CHA in dependence on the pH and extent of calcium deficiency in
the structure CHA was also investigated. It was concluded that the mechanism of sorption of Pb2+ ions on
CHA at pH 5.5 occurs mainly by the isomorphic substitution of Ca2+ ions into ions Pb2+
.