School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore.
J Hazard Mater. 2011 Oct 30;194:162-8. doi: 10.1016/j.jhazmat.2011.07.076. Epub 2011 Aug 5.
We report the synthesis and activation of colloidal carbon nanospheres (CNS) for adsorption of Ag(I) ions from aqueous solutions. CNS (400-500 nm in diameter) was synthesized via simple hydrothermal treatment of glucose solution. The surface of nonporous CNS after being activated by NaOH was enriched with -OH and -COO(-) functional groups. Despite the low surface area (<15m(2)/g), the activated CNS exhibited a high adsorption capacity of 152 mg silver/g. Under batch conditions, all Ag(I) ions can be completely adsorbed in less than 6 min with the initial Ag(I) concentrations lower than 2 ppm. This can be attributed to the minimum mass transfer resistance as Ag(I) ions were all deposited and reduced as Ag(0) nanoparticles on the external surface of CNS. The kinetic data can be well fitted to the pseudo-second-order kinetics model. The adsorbed silver can be easily recovered by dilute acid solutions and the CNS can be reactivated by the same treatment with NaOH solution. The excellent adsorption performance and reusability have also been demonstrated in a continuous mode. The NaOH activated CNS reported here could represent a new type of low-cost and efficient adsorbent nanomaterials for removal of trace Ag(I) ions for drinking water production.
我们报告了胶体碳纳米球（CNS）的合成与活化，用于从水溶液中吸附 Ag（I）离子。CNS（直径 400-500nm）是通过葡萄糖溶液的简单水热处理合成的。经 NaOH 活化后的无孔 CNS 表面富含-OH 和-COO（-）官能团。尽管比表面积较小（<15m(2)/g），但活化后的 CNS 对银的吸附量高达 152mg 银/g。在批处理条件下，当初始 Ag（I）浓度低于 2ppm 时，所有 Ag（I）离子可在不到 6 分钟内完全被吸附。这归因于最小的传质阻力，因为 Ag（I）离子均沉积并还原为 CNS 外表面的 Ag（0）纳米颗粒。动力学数据可以很好地拟合伪二级动力学模型。吸附的银可以很容易地用稀酸溶液回收，并且 CNS 可以通过用 NaOH 溶液进行相同的处理而被重新活化。在连续模式下也证明了其优异的吸附性能和可重复使用性。这里报道的 NaOH 活化的 CNS 可能代表了一种用于饮用水生产的去除痕量 Ag（I）离子的新型低成本、高效吸附剂纳米材料。
