Removal of lead (II) ions from aqueous solution by Hydroxyapatite biosorbent extracted from Ostrich bone

Abstract

Hydroxyapatite (HAp) is a broadly studied bioceramic for biomedical implant and bone tissue regeneration. Despite this, it is a good adsorbent of heavy metal ions. Its chemical formula is Ca10 (PO4)6(OH) 2. It was extracted by the calcination process from Ostrich bone. The obtained HAp was characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy and was used for removal of lead (II) ion from aqueous solutions. A series of experiments were conducted in order to determine the effects of pH, contact time and sorbent dosage in a optimize condition for maximum adsorption. The results showed that the removal efficiency of Pb (II) ions reached 99.04% with an initial concentration of 50 mgL1 , pH range; 3 to7 and 1 hour contact time. The adsorption rate of Pb (II) ions onto the HAp was found incredibly fast and equilibrium was reached within 5 minute. Within this time 72.32% of lead (II) ions were removed. The equilibrium removal process of Pb (II) ions at pH range 4.5-5.5 were well described by the Langmuir isotherm model, with a maximum adsorption capacity of 430.7 mg/g. Key words: Ostrich bone, hydroxyapatite, calcinations, adsorption, Pb (II) ion, pH.