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Eu(III) 和 U(VI) 与氧化石墨烯相互作用的表面络合建模。

Surface Complexation Modeling of Eu(III) and U(VI) Interactions with Graphene Oxide.

机构信息

Department of Environmental Engineering and Earth Sciences, Clemson University , 342 Computer Court, Anderson, South Carolina 29625, United States.

出版信息

Environ Sci Technol. 2016 Feb 16;50(4):1821-7. doi: 10.1021/acs.est.5b05307. Epub 2016 Jan 29.

Abstract

Graphene oxide (GO) has great potential for actinide removal due to its extremely high sorption capacity, but the mechanism of sorption remains unclear. In this study, the carboxylic functional group and an unexpected sulfonate functional group on GO were characterized as the reactive surface sites and quantified via diffuse layer modeling of the GO acid/base titrations. The presence of sulfonate functional group on GO was confirmed using elemental analysis and X-ray photoelectron spectroscopy. Batch experiments of Eu(III) and U(VI) sorption to GO as the function of pH (1-8) and as the function of analyte concentration (10-100, 000 ppb) at a constant pH ≈ 5 were conducted; the batch sorption results were modeled simultaneously using surface complexation modeling (SCM). The SCM indicated that Eu(III) and U(VI) complexation to carboxylate functional group is the main mechanism for their sorption to GO; their complexation to the sulfonate site occurred at the lower pH range and the complexation of Eu(III) to sulfonate site are more significant than that of U(VI). Eu(III) and U(VI) facilitated GO aggregation was observed with high Eu(III) and U(VI) concentration and may be caused by surface charge neutralization of GO after sorption.

摘要

氧化石墨烯(GO)由于其极高的吸附容量,在去除锕系元素方面具有巨大的潜力,但吸附机制仍不清楚。在这项研究中,通过 GO 的酸碱滴定的扩散层模型,对 GO 上的羧酸官能团和一个意想不到的磺酸盐官能团进行了特征描述和定量,这两个官能团被认为是反应性表面位点。GO 上存在磺酸盐官能团的情况通过元素分析和 X 射线光电子能谱得到了证实。在恒定 pH 值约为 5 的条件下,进行了 pH 值(1-8)和分析物浓度(10-100,000 ppb)作为函数的 GO 对 Eu(III)和 U(VI)的吸附批实验;使用表面络合模型(SCM)同时对批吸附结果进行了建模。SCM 表明,Eu(III)和 U(VI)与羧酸盐官能团的络合是它们吸附到 GO 的主要机制;在较低的 pH 值范围内发生了它们与磺酸盐位点的络合,Eu(III)与磺酸盐位点的络合比 U(VI)更显著。在高浓度的 Eu(III)和 U(VI)存在下,观察到 Eu(III)和 U(VI)促进了 GO 的聚集,这可能是由于吸附后 GO 的表面电荷中和。

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