AbstractNovel adsorbents are described for the preconcentration of chromium(VI). Graphene oxide (GO) was modified with various amino silanes containing one, two, or three nitrogen atoms in the molecule. These include 3-aminopropyltriethoxysilane (APTES), N-(3-trimethoxysilylpropyl)ethylenediamine (TMSPEDA), and N1-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPDETA). The resulting GO derivatives were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray fluorescence spectrometry (EDXRF). Adsorption studies show that these GO based sorbents are highly selective for Cr(VI) in the presence of Cr(III) at pH 3.5. Although the amino silanes applied in modification of GO contain different numbers of nitrogen atoms, the maximum adsorption capacities of GO derivatives are very similar (13.3–15.1 mg·g−1). Such results are in accordance with spectroscopy studies which show that the amount of amino silanes attached to GO decreases in the order of APTES > TMSPEDA > TMSPDETA. The APTES-modified GO was applied to selective and sensitive extraction of Cr(VI) ions prior to quantitation by low-power EDXRF using the Cr Kα line. The Cr(VI) ions need not be eluted from the solid adsorbent. The method has a 0.17 ng·mL−1 detection limit, and the recovery is 99.7 ± 2.2% at a spiking level of 10 ng·mL−1. The method was successfully applied to the determination of Cr(VI) in water samples. Graphical abstractGraphene oxide adsorbents modified with various amino silanes are described for the preconcentration and speciation of trace and ultratrace levels of chromium ions.

中文翻译：

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氨基硅烷修饰氧化石墨烯选择性吸附测定六价铬离子

摘要描述了用于预富集六价铬的新型吸附剂。氧化石墨烯（GO）用分子中含有一个、两个或三个氮原子的各种氨基硅烷进行改性。这些包括 3-氨基丙基三乙氧基硅烷 (APTES)、N-(3-三甲氧基甲硅烷基丙基)乙二胺 (TMSPEDA) 和 N1-(3-三甲氧基甲硅烷基丙基)二亚乙基三胺 (TMSPDETA)。通过扫描电子显微镜、X 射线光电子能谱和能量色散 X 射线荧光光谱 (EDXRF) 对所得 GO 衍生物进行了表征。吸附研究表明，在 pH 3.5 的 Cr(III) 存在下，这些 GO 基吸附剂对 Cr(VI) 具有高度选择性。尽管用于GO改性的氨基硅烷含有不同数量的氮原子，但GO衍生物的最大吸附容量非常相似（13.3–15.1 mg·g−1）。这些结果与光谱学研究一致，光谱学研究表明，连接到 GO 上的氨基硅烷的量按 APTES > TMSPEDA > TMSPDETA 的顺序减少。在使用 Cr Kα 线通过低功率 EDXRF 进行定量之前，将 APTES 修饰的 GO 用于选择性且灵敏地萃取 Cr(VI) 离子。Cr(VI) 离子不需要从固体吸附剂中洗脱。该方法的检测限为 0.17 ng·mL−1，加标水平为 10 ng·mL−1 时回收率为 99.7 ± 2.2%。该方法成功应用于水样中Cr(VI)的测定。图文摘要用各种氨基硅烷改性的氧化石墨烯吸附剂用于痕量和超痕量铬离子的预富集和形态形成。