Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031, P. R. China.
Dalton Trans. 2012 May 28;41(20):6182-8. doi: 10.1039/c2dt00054g. Epub 2012 Apr 4.
Graphene oxide nanosheets have attracted multidisciplinary attention due to their unique physicochemical properties. Herein, few-layered graphene oxide nanosheets were synthesized from graphite using a modified Hummers method and were characterized by TEM, AFM, Raman spectroscopy, XPS, FTIR spectroscopy, TG-DTA and acid-base titrations. The prepared few-layered graphene oxide nanosheets were used as adsorbents for the preconcentration of U(VI) ions from large volumes of aqueous solutions as a function of pH, ionic strength and temperature. The sorption of U(VI) ions on the graphene oxide nanosheets was strongly dependent on pH and independent of the ionic strength, indicating that the sorption was mainly dominated by inner-sphere surface complexation rather than by outer-sphere surface complexation or ion exchange. The abundant oxygen-containing functional groups on the surfaces of the graphene oxide nanosheets played an important role in U(VI) sorption. The sorption of U(VI) on graphene oxide nanosheets increased with an increase in temperature and the thermodynamic parameters calculated from the temperature-dependent sorption isotherms suggested that the sorption of U(vi) on graphene oxide nanosheets was an endothermic and spontaneous process. The maximum sorption capacities (Q(max)) of U(VI) at pH 5.0 ± 0.1 and T = 20 °C was 97.5 mg g(-1), which was much higher than any of the currently reported nanomaterials. The graphene oxide nanosheets may be suitable materials for the removal and preconcentration of U(VI) ions from large volumes of aqueous solutions, for example, U(VI) polluted wastewater, if they can be synthesized in a cost-effective manner on a large scale in the future.
氧化石墨烯纳米片因其独特的物理化学性质而引起了多学科的关注。在此，使用改良的 Hummers 法从石墨合成了少层氧化石墨烯纳米片，并通过 TEM、AFM、拉曼光谱、XPS、FTIR 光谱、TG-DTA 和酸碱滴定进行了表征。将制备的少层氧化石墨烯纳米片用作吸附剂，用于从大量水溶液中预浓缩 U(VI)离子，研究了 pH、离子强度和温度对其的影响。U(VI)离子在氧化石墨烯纳米片上的吸附强烈依赖于 pH，而与离子强度无关，这表明吸附主要由内球表面络合主导，而不是由外球表面络合或离子交换主导。氧化石墨烯纳米片表面丰富的含氧官能团在 U(VI)吸附中起重要作用。U(VI)在氧化石墨烯纳米片上的吸附随温度升高而增加，从温度依赖吸附等温线上计算得到的热力学参数表明，U(vi)在氧化石墨烯纳米片上的吸附是一个吸热和自发的过程。在 pH 5.0±0.1 和 T=20°C 时，U(VI)的最大吸附容量（Q(max)）为 97.5mg g(-1)，这远高于目前报道的任何纳米材料。如果未来能够以经济有效的方式大规模合成，氧化石墨烯纳米片可能是从大量水溶液中去除和预浓缩 U(VI)离子的合适材料，例如 U(VI)污染的废水。
