Nano-rod hydroxyapatite for the uptake of nickel ions: Effect of sintering behaviour on adsorption parameters

• Published in: Journal of environmental chemical engineering Vol. 9; no. 5; p. 105931
• Main Authors: Ofudje, Edwin Andrew, Adedapo, Adebusayo Emmanuel, Oladeji, Olugbenga Bowale, Sodiya, Ezekiel Folorunso, Ibadin, Francis Hope, Zhang, Dan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2021
• Subjects: Adsorption; Equilibrium; Hydroxyapatite; Kinetic; Nano-rod; Nano-rod; Hydroxyapatite; Adsorption; Kinetic; Equilibrium
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2021.105931

Sorption studies in batch approach were carried out to investigate the elimination of Ni(II) ions from aqueous solution by fish scale derived nano-rod hydroxyapatite (FSDNHA) obtained via thermal decomposition at 800 and 900 oC respectively. The effects of Ni2+ concentration, contact time, pH, FSDNHA dose and temperature on elimination process were examined. Adsorption studies showed that maximum uptake amount of Ni2+ was attained at initial Ni2+concentration of 240 mg L-1, sorption time of 120 min, FSDNHA dose of 40 mg and solution pH of 6.0. The highest value of R2 obtained for Langmuir, Temkin, and Freundlich isotherms models are (0.996, 0.994, and 0.990) for FSDNHA-800 and (0.998, 0.986, and 0.992) for FSDNHA-900 respectively. The values of the maximum monolayer adsorption capacities obtained from Langmuir isotherm for FSDNHA-800 and FSDNHA-900 are 114.151 and 183.321 mg g-1 respectively. Kinetic modeling of the adsorption data clearly revealed that the sorption of Ni2+ onto the active sites of the FSDNHA surface was governed by Pseudo-first-order kinetic model. Thermodynamics parameters of Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy change (ΔS°) revealed that the sorption of Ni2+on FSDNHA was spontaneous, feasible and exothermic in nature. Well resolved peaks of a characteristic pure hydroxyapatite (HA) containing hydroxyl, phosphate and carbonate groups were obtained as the major functional groups responsible for the uptake of Ni2+, while the morphological analysis by FE-SEM and TEM revealed a nano-rod shape. This current study showed that Ni2+ removal by FSDNHA compared favorable with other adsorbents and is feasible.
[Display omitted]
•Low cost sorbent powder of FSDNHA was successfully obtained from agro-waste of fish scales.•FSDNHA-900 demonstrates high removal of Ni2+ due to high surface area and crystallinity.•Experiment on zero point charge (pHzpc) shows that pH is the most important parameter in the removal of Ni2+.•Kinetics removal of Ni2+ by the synthesized adsorbent confirmed the adsorption mechanism to be chemisorption.•Both FSDNHA-800 and FSDNHA-900 are excellent candidates for the removal of Ni2+.