Removal of phosphates using eggshells and calcined eggshells in high phosphate solutions

• Published in: Applied biological chemistry Vol. 65; no. 1; p. 75
• Main Authors: Park, Jong-Hwan, Choi, Ah-Young, Lee, Su-Lim, Lee, Jae-Hoon, Rho, Jun-Suk, Kim, Seong-Heon, Seo, Dong-Cheol
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.12.2022; Springer Nature B.V
• Subjects: Applied Microbiology; Biological Techniques; Bioorganic Chemistry; Calcium carbonate; Chemical precipitation; Chemistry; Chemistry and Materials Science; Egg shells; Environmental changes; Environmental conditions; Ion exchange; Phosphate; Phosphates; Phosphorus removal; Roasting; Sorption; Eggshell; Sorption; Calcination; Wastewater; Phosphate
• ISSN: 2468-0834; 2468-0842
• DOI: 10.1186/s13765-022-00744-4

This study was conducted to evaluate the phosphate sorption properties of eggshell (ES) and calcined ESs (C-ESs) in a high-concentration phosphate solution. The C-ESs yield decreased rapidly at 900 °C, indicating that the CaCO 3 constituting the ES was converted to CaO by the high calcination temperature. The optimum calcination temperature for phosphate removal using C-ES was 900 °C. The actual sorption amount of phosphate by ES and C-ES900 was in agreement with the Langmuir isothermal sorption equation, and the maximum sorption capacities derived from this equation were 178.6 and 270.3 mg/g, respectively. The sorption rate of phosphate by ES and C-ES900 was divided into two stages: an initial fast sorption stage, followed by a slow sorption stage. The sorption of phosphate by ES was dominantly influenced by the initial pH and salt concentration, whereas C-ES900 exhibited a constant sorption capacity regardless of environmental changes. The SEM–EDS and XRD results demonstrated that phosphate was successfully adsorbed on the ES and C-SE900 surfaces. In this study, it was found that the sorption of phosphate by ES occurred via ion exchange and precipitation reactions and that the sorption of phosphate by C-ES900 was dominantly affected by precipitation. Above all, C-ES can be applied as an effective adsorbent for removing high concentrations of phosphate under a wide range of environmental conditions.