Removal of zinc (II) freom aqueous solution using apatites
Tutor / director / evaluatorCortina Pallás, José Luís
Document typeMaster thesis (pre-Bologna period)
Rights accessOpen Access
The purpose of this project is to study the removal of zinc (II) with three types of apatite, a synthetic deficient calcium apatite (DCa HAp), a biogenic apatite (Apatite II TM) and a synthetic hydroxyapatite produced by a combustion based methodology. As heavy metals are of big health and the environment concern the research focus the attention in one of the most common element in water bodies. The efficiency and the behavior of the selected apatites in different experimental conditions using batch and column experiments have been studied. Additionally to the influence of water composition the influence of the pH and presence of other heavy metals on apatites removal capacities have been also evaluated. Chemical and Mineralogical techniques were used to characterize the properties of the apatites before and after being used on heavy metal extractions. The synthetic calcium deficient hydroxyapatite has the higher removal efficiency at low pH and that both calcium deficient hydroxyapatite and Apatite II TM have similar performance on metals removal efficiency. Batch equilibrium experiments were used to determine the adsorption capacity. DCa HAp, Apatite II TM, and apatite synthetized by combustion reported to have adsorption capacity of 34.0mg g-1 and 30.5mg g-1 and 8.30mg g-1 respectively. The metal extraction mechanisms was shown to be a complex process where the following main processes could be involved: a) dissolution of the apatites realizing Ca(II) and phosphate ions, b) sorption of the metal ions onto the apatite structure and c) formation of metal-phosphate mineral phases as Hopeite. The presence and morphology of Hopeite was identified by FSEM-EDAX and it was confirmed by X-Ray Diffraction.