Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Institute of Nuclear Science and Technology , Sichuan University , Chengdu 610064 , China.
CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , China.
Environ Sci Technol. 2019 May 7;53(9):5102-5110. doi: 10.1021/acs.est.9b00656. Epub 2019 Apr 15.
Molecular dynamics (MD) simulations were performed to investigate the influence of curvature and backbone rigidity of an oxygenated surface, here graphene oxide (GO), on its adsorption of uranyl in collaboration with humic acid (HA). The planar curvature of GO was found to be beneficial in impeding the folding of HA. This, together with its rigidity that helps stabilize the extended conformation of HA, offered rich binding sites to interact with uranyl with only marginal loss of binding strength. According to our simulations, the interaction between uranyl and GO was mainly driven by electrostatic interactions. The presence of HA not only provided multiple sites to compete/cooperate with GO for adsorption of free uranyl but also interacted with GO acting as a "bridge" to connect uranyl and GO. The potential of mean force (PMF) profiles implied that HA significantly enhanced the interaction strength between uranyl and GO and stabilized the uranyl-GO complex. Meanwhile, GO could reduce the diffusion coefficients of uranyl and HA and retard their migrations in aqueous solution. This work provides theoretical hints on the GO-based remediation strategies for the sites contaminated by uranium or other heavy metal ions and oxygenated organic pollutants.
采用分子动力学（MD）模拟方法研究了含氧表面（即氧化石墨烯，GO）曲率和主链刚性对其与腐殖酸（HA）共吸附铀酰的影响。结果表明，GO 的平面曲率有利于阻碍 HA 的折叠。GO 的刚性有助于稳定 HA 的伸展构象，这为与铀酰相互作用提供了丰富的结合位点，同时结合强度的损失微乎其微。根据我们的模拟结果，铀酰与 GO 的相互作用主要是由静电相互作用驱动的。HA 的存在不仅提供了多个位点与 GO 竞争/合作吸附游离铀酰，而且还与 GO 相互作用，充当“桥梁”将铀酰和 GO 连接起来。平均力势（PMF）曲线表明，HA 显著增强了铀酰与 GO 之间的相互作用强度，并稳定了铀酰-GO 配合物。同时，GO 可以降低铀酰和 HA 的扩散系数，减缓它们在水溶液中的迁移。这项工作为基于 GO 的修复策略提供了理论依据，这些策略可用于修复被铀或其他重金属离子和含氧有机污染物污染的场地。
