School of Environment & Natural Resources, Renmin University of China, Beijing, 100872, People's Republic of China.
Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, People's Republic of China.
Environ Sci Pollut Res Int. 2023 Sep;30(45):101433-101444. doi: 10.1007/s11356-023-29374-z. Epub 2023 Aug 31.
This study aimed to utilize synthesized graphene oxide (GO) for adsorptive removal of cobalt ions and investigate the adsorption mechanism using advanced techniques such as X-ray absorption spectra (XAFS). The GO was synthesized via an improved Hummers method, resulting in high surface area (93.7 m/g) and abundant oxygen-containing functional groups. Various characterizations, including SEM, TEM, Raman, FT-IR, TG, potentiometric titrations, and N sorption-desorption measurements, were employed to characterize the GO. The adsorption behavior of GO towards Co was investigated, and the results showed that the adsorption process followed a pseudo-second-order kinetic model and the Langmuir model, with a maximum sorption capacity of 93.7 mg/g. The adsorption process was chemisorption and endothermic, with GO showing adsorption selectivity order of Co > Sr > Cs. Based on various characterizations such as X-ray absorption near-edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), FT-IR, and XPS, the sorption mechanism of Co onto GO was discussed, with the results indicating that coordination and electrostatic interaction were the primary adsorption mechanisms, with oxygen-containing functional groups playing a vital role. The first coordinating atom for Co was O, and the coordination environment was similar to that of cobalt acetate and CoO. Overall, this study provides comprehensive understanding of the adsorption behavior and mechanism of Co onto GO, highlighting its potential as an effective adsorbent for removing nuclides from aqueous solution.
本研究旨在利用合成的氧化石墨烯（GO）吸附去除钴离子，并利用 X 射线吸收光谱（XAFS）等先进技术研究吸附机制。GO 通过改良的 Hummers 法合成，具有高表面积（93.7 m/g）和丰富的含氧官能团。采用 SEM、TEM、Raman、FT-IR、TG、电位滴定和 N 吸附-解吸测量等各种表征方法对 GO 进行了表征。研究了 GO 对 Co 的吸附行为，结果表明吸附过程遵循准二级动力学模型和 Langmuir 模型，最大吸附容量为 93.7 mg/g。吸附过程为化学吸附和吸热过程，GO 对 Co 的吸附选择性顺序为 Co> Sr> Cs。基于 X 射线吸收近边光谱（XANES）、扩展 X 射线吸收精细结构（EXAFS）、FT-IR 和 XPS 等各种表征，讨论了 Co 在 GO 上的吸附机制，结果表明配位和静电相互作用是主要的吸附机制，含氧官能团起着至关重要的作用。Co 的第一配位原子为 O，配位环境与醋酸钴和 CoO 相似。总的来说，本研究全面了解了 Co 在 GO 上的吸附行为和机制，突出了其作为从水溶液中去除核素的有效吸附剂的潜力。
