Size characterization of bentonite colloids by different methods
Size characterization of bentonite colloids by different methods
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DOI：
10.1021/ac010116t
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发表时间：
2001-09-01
影响因子：
7.4
通讯作者：
Kim, JI
中科院分区：
文献类型：
--
作者：
Plaschke, M;Schäfer, T;Kim, JI
The size and shape of colloids released from a natural bentonite into a low-mineralized groundwater are investigated using various colloid characterization methods. For the applied methods such as atomic force microscopy (AFM) laser-induced breakdown detection (LIBD), photon correlation spectroscopy (PCS), and flow field-flow fractionation coupled to ICP-mass spectrometric detection (FFFF-ICPMS), the respective raw size data have to be corrected in order to consider chemical composition and shape of the colloids as well as instrumental artifacts. Noncontact mode AFM of the bentonite colloids shows disklike shapes of stacked smectite platelets with a mean height-to-diameter proportion (aspect ratio) of similar to1/10. A broad particle number size distribution is determined by image processing with a mean particle diameter of 73 mn. In agreement with AFM, a broad size distribution is also found by PCS and FFFF-ICPMS. Likewise, mean particle sizes found by (LIBD) (67 +/- 13 nm) and FFFF-ICPMS (maximum in the number size distribution, similar to 70 nm) are in fair agreement with the AFM data. Somewhat higher values are obtained by PCS, where mean particle diameters of the intensity-weighted size distributions of larger than 200 nm are found (depending on the algorithm used for data processing). The influence of the disklike particle shape on the results of the individual methods is discussed. As a conclusion, the application of different colloid characterization methods is a prerequisite to get complementary information about colloid size and shape, which is essential for the understanding of natural colloidal systems.
