About 8 million tons of eggshell waste are annually produced worldwide. Most of this material is disposed at landfills with odor production and microbial growth, while only occasionally it is used as fertilizer, soil conditioner or additive for animal feed. However, the conversion of this waste to new useful products is of high economic and environmental interest. In this study, hydroxyapatite was synthesized from eggshell waste by using a simple and inexpensive protocol and applied for Co2+ removal from aqueous solutions. The effects of contact time and initial metal concentration were investigated in batch experiments. Eggshell-derived hydroxyapatite (ESHAP) before and after the adsorption experiments was characterized by X-ray diffraction and scanning electron microscopy. The Co2+ and Ca2+ concentrations were analyzed by inductively coupled plasma atomic emission spectrometry. The adsorption process was rapid and reached equilibrium within 80 min. The metal removal efficiency was in the range 70-80% which is generally higher than other waste-derived adsorbents. After metal ions adsorption the starting ESHAP particles of sheet or flake-like structure were modified showing well-shaped tabular crystals. These morphological changes suggest dissolution-precipitation phenomena play an important role in the metal removal mechanism. The removal of metal ions from the solution is accompanied by the increase of Ca2+ concentrations in the solutions suggesting that the ion exchange mechanism is partly involved in the adsorption process. The overall mechanism for Co2+ removal by ESHAP involves rapid surface adsorption of metal ions on the ESHAP surface, ion exchange with Ca2+ of ESHAP and partial dissolution/precipitation resulting in the formation of a Co-bearing phosphate. The results of this study showed that the conversion of eggshell waste to a low-cost adsorbent for the treatment of metal contaminated waters could contribute to the environmentally friendly disposal of this waste.

Eggshell waste as a valuable resource for cobalt remediation / Luana, Archilletti; Medeghini, Laura; De Vito, C; Mignardi, Silvano. - (2019). (Intervento presentato al convegno 17th International Waste Management and Landfill Symposium tenutosi a Santa Margherita di Pula (CA) - Italy).

Eggshell waste as a valuable resource for cobalt remediation

Laura Medeghini;De Vito C;Silvano Mignardi
2019

Abstract

About 8 million tons of eggshell waste are annually produced worldwide. Most of this material is disposed at landfills with odor production and microbial growth, while only occasionally it is used as fertilizer, soil conditioner or additive for animal feed. However, the conversion of this waste to new useful products is of high economic and environmental interest. In this study, hydroxyapatite was synthesized from eggshell waste by using a simple and inexpensive protocol and applied for Co2+ removal from aqueous solutions. The effects of contact time and initial metal concentration were investigated in batch experiments. Eggshell-derived hydroxyapatite (ESHAP) before and after the adsorption experiments was characterized by X-ray diffraction and scanning electron microscopy. The Co2+ and Ca2+ concentrations were analyzed by inductively coupled plasma atomic emission spectrometry. The adsorption process was rapid and reached equilibrium within 80 min. The metal removal efficiency was in the range 70-80% which is generally higher than other waste-derived adsorbents. After metal ions adsorption the starting ESHAP particles of sheet or flake-like structure were modified showing well-shaped tabular crystals. These morphological changes suggest dissolution-precipitation phenomena play an important role in the metal removal mechanism. The removal of metal ions from the solution is accompanied by the increase of Ca2+ concentrations in the solutions suggesting that the ion exchange mechanism is partly involved in the adsorption process. The overall mechanism for Co2+ removal by ESHAP involves rapid surface adsorption of metal ions on the ESHAP surface, ion exchange with Ca2+ of ESHAP and partial dissolution/precipitation resulting in the formation of a Co-bearing phosphate. The results of this study showed that the conversion of eggshell waste to a low-cost adsorbent for the treatment of metal contaminated waters could contribute to the environmentally friendly disposal of this waste.
2019
17th International Waste Management and Landfill Symposium
eggshell waste; Co2+ adsorption; Hydroxyapatite; Pakhomovskyite; Kinetics; Isotherm
04 Pubblicazione in atti di convegno::04b Atto di convegno in volume
Eggshell waste as a valuable resource for cobalt remediation / Luana, Archilletti; Medeghini, Laura; De Vito, C; Mignardi, Silvano. - (2019). (Intervento presentato al convegno 17th International Waste Management and Landfill Symposium tenutosi a Santa Margherita di Pula (CA) - Italy).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1361550
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