Obtaining new nanocomposites with sorption properties towards chromium is highly important not only from the environmental point of view but also for developing eco-friendly methods of chromium determination. The potential use of aluminum oxide-coated nano-graphite (Al₂O₃/nano-G) as a new nanosorbent in ultrasound-assisted dispersive micro-solid-phase extraction (DMSPE) for rapid speciation of trace chromium(III) and chromium(VI) ions in natural water was evaluated. In the developed method, the crucial issue is the new nanocomposite synthesized by coating alumina on a nano-graphite surface with sorption properties. Structural researches of the nanocomposite were carried out by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and Raman spectroscopy. Maximum adsorption capacity of Al₂O₃/nano-G towards Cr(III) was 32.8 mg g⁻¹. The influence of the method’s factors like pH, sample volumes, contact time, coexisting ions, and humic acid on the recovery of chromium was examined. The nanocomposites have been found to be stable and effective as a sorbent in water with high concentrations of selected cations and anions present in water as well as in water of various pH. Al₂O₃/nano-G is selective for Cr(III) in presence of Cr(VI). Cr(III) was determined by the developed method, total Cr after reduction of Cr(VI) to Cr(III), and Cr(VI) was calculated as the difference between total Cr and Cr(III). After sorption, the nanocomposite with chromium was collected on 5-mm diameter filters and analyzed by energy-dispersive X-ray fluorescence spectrometry (EDXRF) to determine the chromium concentration. The method was characterized by correlation coefficient 0.999, limit of detection (LOD) 0.04 ng mL⁻¹, and relative standard deviation (RSD) 3.5%. Al₂O₃/nano-G combined with proposed DMSPE/EDXRF was verified by analysis of certificate reference material of natural water (NIST 1640a).

中文翻译：

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氧化铝/纳米石墨复合材料作为新型纳米吸附剂，用于 EDXRF 选择性吸附、预富集和测定水样中的铬

获得具有铬吸附特性的新型纳米复合材料不仅从环境角度来看非常重要，而且对于开发环保的铬测定方法也非常重要。氧化铝涂层纳米石墨（Al ₂ O ₃ /nano-G）作为新型纳米吸附剂在超声辅助分散微固相萃取（DMSPE）中的潜在用途，用于痕量铬（III）和铬的快速形态形成(VI)评价天然水中的离子。在所开发的方法中，关键问题是通过在具有吸附性能的纳米石墨表面上涂覆氧化铝来合成新型纳米复合材料。通过扫描电子显微镜（SEM）、粉末X射线衍射（XRD）和拉曼光谱对纳米复合材料进行了结构研究。Al ₂ O ₃ /nano-G对Cr(III)的最大吸附容量为32.8 mg g ^-1。考察了该方法的 pH 值、样品体积、接触时间、共存离子和腐殖酸等因素对铬回收率的影响。已发现纳米复合材料在水中以及各种pH值的水中存在高浓度的选定阳离子和阴离子的水中作为吸附剂是稳定且有效的。Al ₂ O ₃ /nano-G 在 Cr(VI) 存在下对 Cr(III) 具有选择性。Cr(III)采用所开发的方法测定，Cr(VI)还原为Cr(III)后的总Cr，Cr(VI)计算为总Cr与Cr(III)之间的差值。吸附后，将含铬的纳米复合材料收集在直径为 5 毫米的过滤器上，并通过能量色散 X 射线荧光光谱法 (EDXRF) 进行分析，以确定铬浓度。该方法的相关系数为0.999，检测限(LOD)为0.04 ng mL ^-1，相对标准偏差(RSD)为3.5%。Al ₂ O ₃ /nano-G 与所提出的 DMSPE/EDXRF 的结合通过天然水证书参考材料 (NIST 1640a) 的分析得到验证。