The exploration and rational design of easily separable and highly efficient sorbents with the sufficient capability of retaining radioactive and toxic uranium U(VI) is paramount. In this study, a hydroxyapatite (HAP) biochar nanocomposite (BR/HAP) was successfully fabricated from rice straw biochar (BR), to be used as a new and efficient adsorbent for removing U(VI) from aqueous solution. Both BR and the BR/HAP composite were characterized via Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) techniques. Batch test results showed that BR/HAP exhibited remarkably higher adsorption capacity than the raw BR. A pseudo-second order kinetic model thoroughly explained the adsorption kinetics, providing the maximum U(VI) adsorption capacities (q_e) of 110.56 mg g⁻¹ (R² = 0.98) and 428.25 mg g⁻¹ (R² = 0.99), for BR and BR/HAP, respectively, which was indicative of the rate-limited sorption via diffusion or surface complexation after rapid initial adsorption steps. The Langmuir isotherm model fitted the experimental data to accurately simulate the adsorption of U(VI) onto BR and BR/HAP (R² = 0.97 and R² = 0.99). The thermodynamic results showed negative values for ΔG°, clearly indicating that the reaction was spontaneous, as well as positive values for ΔH° (11.04 kJ mol⁻¹ and 28.86 kJ mol⁻¹, respectively) and ΔS° (88.97 kJ mol⁻¹ K⁻¹, and 183.42 kJ mol⁻¹ K⁻¹), making clear the endothermic nature of U(VI) adsorption onto both sorbents, with an increase in randomness at a molecular level. FTIR spectroscopy and XPS spectrum further confirmed that the primary mechanisms were ion exchange with UO₂²⁺ and surface complexion by –OH and –COOH. In addition, BR/HAP showed an excellent reusability, making it a promising candidate as a new sorbent for U(VI) removal from wastewater. In view of that, it would be interesting to perform future research to explore practical implications of this sorbent material regarding protection from environmental and public health issues related to that pollutant.

探索和合理设计易于分离和高效的吸附剂，并具有足够的保留放射性和有毒铀 U(VI) 的能力是至关重要的。在这项研究中，以稻草生物炭（BR）为原料成功制备了羟基磷灰石（HAP）生物炭纳米复合材料（BR/HAP），用作一种新型高效吸附剂，用于去除水溶液中的 U（VI）。BR 和 BR/HAP 复合材料均通过 Brunauer-Emmett-Teller (BET)、扫描电子显微镜 (SEM)、能量色散光谱 (EDS)、透射电子显微镜 (TEM)、X 射线衍射 (XRD)、傅立叶进行表征变换红外光谱 (FTIR) 和 X 射线光电子能谱 (XPS) 技术。批量测试结果表明，BR/HAP 表现出明显高于原始 BR 的吸附能力。_e ) 对于 BR 和 BR/HAP，分别为 110.56 mg g ^-1 (R ²  = 0.98) 和 428.25 mg g ^-1 (R ² = 0.99)，这表明通过扩散或表面络合的速率限制吸附经过快速的初始吸附步骤。Langmuir 等温线模型拟合实验数据以准确模拟 U(VI) 在 BR 和 BR/HAP 上的吸附（R ²  = 0.97 和 R ²  = 0.99）。热力学结果显示ΔG°为负值，清楚地表明反应是自发的，ΔH°（分别为11.04 kJ mol ^-1和28.86 kJ mol ^-1）和ΔS°（88.97 kJ mol ^-1）为正值钾^-1和 183.42 kJ mol ^-1 K ^-1 )，清楚地表明 U(VI) 吸附到两种吸附剂上的吸热性质，并在分子水平上增加了随机性。FTIR 光谱和XPS 光谱进一步证实，主要机制是与UO ₂ ^{2+ 的}离子交换和-OH 和-COOH 的表面络合。此外，BR/HAP 显示出优异的可重复使用性，使其成为从废水中去除 U(VI) 的新型吸附剂的有希望的候选者。有鉴于此，开展未来的研究以探索这种吸附剂材料在防止与该污染物相关的环境和公共健康问题方面的实际意义将是很有趣的。