Department of Integrated Energy and Infra system, Kangwon National University, Kangwondaehak-gil, 1, Chuncheon-si, Gangwon-do 24341, Republic of Korea.
Disposal Performance Demonstration Research Division, Korea Atomic Energy Research Institute, Daejeon, 34057, Republic of Korea.
Environ Pollut. 2022 Nov 15;313:120138. doi: 10.1016/j.envpol.2022.120138. Epub 2022 Sep 8.
The adsorption of radioactive iodine, which is capable of presenting high mobility in aquatic ecosystems and generating undesirable health effects in humans (e.g., thyroid gland dysfunction), was comprehensively examined using pristine spent coffee ground biochar (SCGB) and bismuth-impregnated spent coffee ground biochar (Bi@SCGB) to provide valuable insights into the variations in the adsorption capacity and mechanisms after pretreatment with Bi(NO). The greater adsorption of radioactive iodine toward Bi@SCGB (adsorption capacity (Q) = 253.71 μg/g) compared to that for SCGB (Q = 23.32 μg/g) and its reduced adsorption capability at higher pH values provide evidence that the adsorption of radioactive iodine with SCGB and Bi@SCGB is strongly influenced by the presence of bismuth materials and the electrostatic repulsion between their negatively charged surfaces and negatively charged radioactive iodine (IO). The calculated R values for the adsorption kinetics and isotherms support that chemisorption plays a crucial role in the adsorption of radioactive iodine by SCGB and Bi@SCGB in aqueous phases. The adsorption of radioactive iodine onto SCGB was linearly correlated with the contact time (h), and the diffusion of intra-particle predominantly determined the adsorption rate of radioactive iodine onto Bi@SCGB (C (129.20) > C (42.33)). Thermodynamic studies revealed that the adsorption of radioactive iodine toward SCGB (ΔG° = -8.47 to -7.83 kJ/mol; ΔH° = -13.93 kJ/mol) occurred exothermically and that for Bi@SCGB (ΔG° = -15.90 to -13.89 kJ/mol; ΔH° = 5.88 kJ/mol) proceeded endothermically and spontaneously. The X-ray photoelectron spectroscopy (XPS) analysis of SCGB and Bi@SCGB before and after the adsorption of radioactive iodine suggest the conclusion that the change in the primary adsorption mechanism from electrostatic attraction to surface precipitation upon the impregnation of bismuth materials on the surfaces of spent coffee ground biochars is beneficial for the adsorption of radioactive iodine in aqueous phases.
采用原始咖啡渣生物炭 (SCGB) 和负载铋的咖啡渣生物炭 (Bi@SCGB) 全面研究了放射性碘的吸附，放射性碘在水生生态系统中具有很高的迁移能力，并会对人体健康产生不良影响（例如甲状腺功能障碍）。通过用 Bi(NO₃)预处理来提供对吸附容量和机制变化的有价值的见解。与 SCGB（吸附容量 (Q) = 23.32μg/g）相比，Bi@SCGB 对放射性碘的吸附量更大（Q = 253.71μg/g），并且在较高 pH 值下其吸附能力降低，这表明 SCGB 和 Bi@SCGB 对放射性碘的吸附强烈受到铋材料的存在和它们带负电荷的表面与带负电荷的放射性碘 (IO) 之间的静电排斥的影响。吸附动力学和等温线的计算 R 值支持化学吸附在水相中 SCGB 和 Bi@SCGB 对放射性碘的吸附中起关键作用。放射性碘在 SCGB 上的吸附与接触时间 (h) 呈线性相关，而内颗粒扩散主要决定了放射性碘在 Bi@SCGB 上的吸附速率（C (129.20) > C (42.33)）。热力学研究表明，SCGB 对放射性碘的吸附（ΔG° = -8.47 至 -7.83 kJ/mol；ΔH° = -13.93 kJ/mol）是放热的，而 Bi@SCGB 对放射性碘的吸附（ΔG° = -15.90 至 -13.89 kJ/mol；ΔH° = 5.88 kJ/mol）是吸热的和自发的。放射性碘吸附前后 SCGB 和 Bi@SCGB 的 X 射线光电子能谱 (XPS) 分析表明，在咖啡渣生物炭表面负载铋材料后，主要吸附机制从静电吸引变为表面沉淀的变化有利于放射性碘在水相中的吸附。
