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 CaCO3 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.

中文翻译：

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在高磷酸盐溶液中使用蛋壳和煅烧蛋壳去除磷酸盐

本研究旨在评估蛋壳 (ES) 和煅烧 ES (C-ES) 在高浓度磷酸盐溶液中的磷酸盐吸附特性。C-ESs 产率在 900 °C 时迅速下降，表明构成 ES 的 CaCO3 在高煅烧温度下转化为 CaO。使用 C-ES 去除磷酸盐的最佳煅烧温度为 900 °C。ES和C-ES900对磷酸盐的实际吸附量符合Langmuir等温吸附方程，由该方程得出的最大吸附量分别为178.6和270.3 mg/g。ES和C-ES900对磷酸盐的吸附速率分为两个阶段：初始快速吸附阶段，随后是缓慢吸附阶段。ES对磷酸盐的吸附主要受初始pH和盐浓度的影响，而无论环境如何变化，C-ES900 都表现出恒定的吸附能力。SEM-EDS 和 XRD 结果表明磷酸盐成功吸附在 ES 和 C-SE900 表面。在这项研究中，发现 ES 对磷酸盐的吸附是通过离子交换和沉淀反应发生的，而 C-ES900 对磷酸盐的吸附主要受沉淀影响。最重要的是，C-ES 可用作在各种环境条件下去除高浓度磷酸盐的有效吸附剂。发现 ES 对磷酸盐的吸附是通过离子交换和沉淀反应发生的，而 C-ES900 对磷酸盐的吸附主要受沉淀影响。最重要的是，C-ES 可用作在各种环境条件下去除高浓度磷酸盐的有效吸附剂。发现 ES 对磷酸盐的吸附是通过离子交换和沉淀反应发生的，而 C-ES900 对磷酸盐的吸附主要受沉淀影响。最重要的是，C-ES 可用作在各种环境条件下去除高浓度磷酸盐的有效吸附剂。