This paper reports on the hydrothermal synthesis of ecological-nanohydroxyapatite (ECO-NHAp) using Ca extracted from fine-grained calcareous sludge via acid dissolution for use as an adsorbent in the removal of Cd²⁺ from wastewater. The ECO-NHAp was characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller surface analysis, and nuclear magnetic resonance spectrometry. Batch adsorption experiments were performed to investigate the effects of contact time and initial Cd²⁺ concentration on adsorption efficiency. Kinetics and adsorption behavior were examined using Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, and Sips isotherms. Overall, the Cd²⁺ adsorption capacity of ECO-NHAp was good (35.09 mg/g) and Langmuir isotherms indicated monolayer adsorption. After controlling for entropy, we found the changes in enthalpy and entropy were positive, while the Gibbs energy was negative. The proposed ECO-NHAp synthesized using raw materials from fine-grained calcareous sludge could be used as a rapid adsorbent for metal ion extraction.

本文报道了利用酸溶解从细粒钙质污泥中提取的Ca，水热合成生态纳米羟基磷灰石（ECO-NHAp），用作吸附剂去除废水中的Cd ²⁺ 。使用傅里叶变换红外光谱、透射电子显微镜、Brunauer-Emmett-Teller 表面分析和核磁共振光谱法对 ECO-NHAp 进行了表征。进行批量吸附实验以研究接触时间和初始Cd ²⁺浓度对吸附效率的影响。使用 Langmuir、Freundlich、Dubinin-Radushkevich、Temkin 和 Sips 等温线检查动力学和吸附行为。总体而言，ECO-NHAp对Cd ²⁺的吸附能力良好（35.09 mg/g），Langmuir等温线显示单层吸附。控制熵后，我们发现焓和熵的变化为正，而吉布斯能为负。使用细粒钙质污泥的原料合成的ECO-NHAp可用作金属离子萃取的快速吸附剂。