Fabrication of Porous Hydroxyapatite Granules as an Effective Adsorbent for the Removal of Aqueous Pb(II) Ions

Abstract

Porous hydroxyapatite (HAp) granules have been successfully fabricated from a HAp powder precursor and polyvinyl alcohol (PVA) additive by a simple sintering process. The composition and microstructures of the HAp were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer. The effects of sintering temperature and PVA/HAp mass ratios on color, water stability, morphology, and chemical composition of HAp are discussed. Optimum conditions for the fabrication of HAp granules were found to be a PVA/HAp mass ratio of 3/20 and a sintering temperature of 600°C for 4 h. Accordingly, the obtained HAp is white in color, is in the granular form with a size of about 2 × 10 mm, and has a specific surface area of 70.6 m2/g. The adsorption of Pb2+ onto the as-prepared HAp granules was carried out in aqueous solution by varying the pH, the adsorbent dose, the initial concentration of Pb2+, and the contact time. The results of adsorption stoichiometry of Pb2+ on the HAp granule adsorbent were fitted to the Langmuir adsorption isotherm model (R2 = 0.99). The adsorption capacity and removal efficiency of the HAp granule adsorbent for Pb2+ under optimal conditions were found to be 7.99 mg/g and 95.92%, respectively. The adsorption process obeyed a pseudo-second-order kinetic model with R2∼1. The porous HAp granules studied in this work showed potential for the removal of Pb2+ from industrial wastewater.

Synthesis and Characterization of Hydroxyapatite- (HAP-) Clay Composites and Adsorption Studies on Methylene Blue for Water Treatment

“…e wet precipitation method is preferred because only water is produced as a by-product. Also, the risk of contamination during processing is low, leading to the formation of high purity crystals, and it is cheap [18]. is research adopts the wet precipitation method for the HAP synthesis (considering the advantages: affordability, high chemical and thermal stability, ionic exchange capacity, and adsorption affinity) and, consequently, forms composites with clay minerals for the MB removal from water [19][20][21].…”

Green synthesis of Sodium alginate mediated Fluorapatite Nanoparticle via Sol-Gel method

“…FA particle diameters were about 49 nm in length and 10 nm in wide with less agglomeration and small size due to presence of SA as a bio-stabilizer. By fluoride ion substitution the morphology of particles from HA to FA slightly changed and there is no doubt that presence of SA promotes the particle size become smaller with better crystallinity [31,32]. As in can be seen in EDX results of HA and FA all essential elements were indicated specially fluoride ion emerged at 0.67 eV in FA.…”

Removal of Pb(II) using Hydroxyapatite from Golden Snail Shell (Pomacea canaliculata L.) Modified with Silica

“…Meanwhile, at pH 8, the presence of OHcaused Pb in solution to form Pb(OH)2, Pb(OH)3 and Pb(OH) + which reduced Pb 2+ absorbed by hydroxyapatite and hydroxyapatite-SiO2 composite (Xu, Tan, Chen, & Wang, 2008). Another study investigated that the precipitate of Pb(OH)2 is formed at pH 7.5 (Le et al, 2019). The % removal of Pb(II) using hydroxyapatite-SiO2 composite is greater than hydroxyapatite.…”

“…The result shows that hydroxyapatite-SiO2 composite can effectively use as an adsorbent of Pb(II). Le et al, 2019Humelnicu, Ignat, & Suchea, 2015Humelnicu et al, 2015Adebisi, 2017Zhang, Luan, Chen, Ke, & Zhang (2019) Tazar & Ozer (2020 In this study In this study Adsorption Kinetic Adsorption kinetic models were studied to determine the mechanism of adsorption, control of adsorption steps such as chemical reactions, transport of mass, and kinetics adsorption (Rao et al, 2011). The pseudo-first-order and pseudo-second-order are used to describe kinetic models in this study.…”