Sakurai Hiroki, Ebihara Noboru, Osawa Eiji, Takahashi Makoto, Fujinami Masanori, Oguma Koichi
Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, Japan.
Anal Sci. 2006 Mar;22(3):357-62. doi: 10.2116/analsci.22.357.
A nanodiamond with a mean particle size of 4 nm, which was prepared by the detonation of a nanodiamond, has been characterized and used as a collector for tungstate in water samples. An aqueous solution of nanodiamond was found to be stable over the pH range from 3 to 10. Coagulation of the nanodiamond could be brought about by adding an electrolyte solution. The adsorption characteristics of nanodiamond have been elucidated to be attributable to amino groups on its surface by the elemental-analysis data and the zeta potential measured in weak acid media. The unique adsorption properties of the nanodiamond for oxoacid anions were applied to a selective preconcentration method for tungstate in water samples. An appropriate amount of nanodiamond was added to a sample solution at pH 5 and a calcium chloride solution was added to aggregate nanodiamond. The sample solution was then allowed to stand for 2 h and centrifuged. The nanodiamond was transferred onto a membrane filter, washed with a diluted calcium chloride solution and treated in advance of an ICP-AES measurement by either of the following procedures: (a) redispersion of the nanodiamond into dilute nitric acid with an ultrasonic washer and (b) ashing of the membrane filter and the coagulated nanodiamond at 700 degrees C, followed by a treatment of the ash with hydrochloric and tartaric acids. The average recovery of tungstate from 100-ml artificial river-water was found to be 99% at the 0.25 ppm level with an RSD of 2.2% (n = 3). The concentration factor at present is 10.
通过爆轰法制备的平均粒径为4 nm的纳米金刚石已被表征，并用作水样中钨酸盐的捕集剂。发现纳米金刚石水溶液在pH值3至10的范围内是稳定的。添加电解质溶液可使纳米金刚石发生凝聚。通过元素分析数据和在弱酸介质中测量的zeta电位，已阐明纳米金刚石的吸附特性归因于其表面的氨基。纳米金刚石对含氧酸根阴离子的独特吸附性能被应用于水样中钨酸盐的选择性预富集方法。在pH 5的样品溶液中加入适量的纳米金刚石，并加入氯化钙溶液使纳米金刚石凝聚。然后将样品溶液静置2 h并离心。将纳米金刚石转移到膜滤器上，用稀释的氯化钙溶液洗涤，并通过以下任一程序在进行ICP-AES测量之前进行处理：(a)用超声清洗器将纳米金刚石重新分散到稀硝酸中；(b)在700℃下将膜滤器和凝聚的纳米金刚石灰化，然后用盐酸和酒石酸处理灰分。在0.25 ppm水平下，从100 ml人工河水中回收钨酸盐的平均回收率为99%，相对标准偏差为2.2%（n = 3）。目前的浓缩因子为10。
