Valorization of Eggshell Biowaste for Sustainable Environmental Remediation

Silvano Mignardi,Caterina De Vito,Laura Medeghini,Luana Archilletti

doi:10.1038/s41598-020-59324-5

Silvano Mignardi, Caterina De Vito + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-59324-5

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Journal: Scientific Reports	Publication Date: Feb 12, 2020
Citations: 63	License type: open-access

Affiliation: Sapienza University of Rome

Abstract

The management of large amounts of eggshell waste annually produced in the world is problematic as generally this material is only disposed at landfills with odor production and microbial growth. On the contrary, significant environmental and economic advantages could be obtained transforming this biowaste into new value-added products. Eggshell biowaste was the starting material for the synthesis of hydroxyapatite by a simple and sustainable procedure and applied for the removal of Co2+ from aqueous solutions. The effects of contact time and initial metal concentration were investigated in batch experiments. Eggshell-based hydroxyapatite (ESHAP) before and after Co2+ removal was characterized by X-ray diffraction and scanning electron microscopy. The process was rapid and reached equilibrium within 80 min. The removal efficiency was in the range 70–80% which is generally higher than other waste-derived adsorbents. Adsorption of Co2+ on the surface of ESHAP particles and ion exchange with Ca2+ resulting in the formation of a Co-phosphate are the main mechanisms of the metal removal. The conversion of eggshell waste to a low-cost adsorbent for the treatment of metal contaminated waters could contribute to a more sustainable and effective management of this biowaste.

Highlights

The management of huge amounts of waste from the food processing industry is a challenging problem
The main objective of this study is to evaluate the ability of eggshell-based HAP (ESHAP) in the removal of Co2+ ions from aqueous solutions
After the removal of Co2+ the morphology of the grains was significantly modified showing well-shaped tabular crystals, in agreement with the habit of natural pakhomovskyite, in the range 5–10 μm (Fig. 2b). This morphological change implies that during the removal of Co2+ from aqueous solution dissolution-precipitation phenomena occurred resulting in the crystallization of pakhomovskyite

Summary

Introduction

The management of huge amounts of waste from the food processing industry is a challenging problem. The 3R principles (reduce, reuse and recycle) are the basis of the “Circular Economy”[1] In this way, waste can be converted into valuable and useful resources improving both sustainable development and adequate waste management strategies[2,3]. The shell weighs about 11% of the total mass of the egg and consists of calcium carbonate (94%), magnesium carbonate (1%), calcium phosphate (1%) and organic matter (4%)[12,13] In this view, the reuse of eggshell waste in numerous applications would produce both environmental and economic advantages. The options for the valorization of this waste include the use of eggshell as a biological template for catalysis and antibacterial applications, the production of food additives, soil conditioners, the base material for cosmetics, pure calcium carbonate and biomaterials[1,7,12,14,15,16].

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