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Science 10 November 2006:
Vol. 314. no. 5801, p. 889
DOI: 10.1126/science.314.5801.889f
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Figure 1 Mesoporous materials such as zeolites have high sorption capacities for separations, but mass transport through these materials can be a limiting factor. Nanoparticles offer potentially high surface areas and rapid contact with the sample, but as their size decreases, their separation from solution becomes more difficult. Magnetic separation routes, either batchwise or continuously from solution, that are useful with larger particles would appear to need prohibitively large-field gradients for submicrometer-sized particles. Yavuz et al. (p. 964) now show that this supposed limitation does not apply to single-domain magnetite particles about 10 nanometers in diameter; at relatively modest fields, these particles aggregated, apparently because of their much higher surface field strength compared to multidomain particles. Particles of different sizes could be separated, and sorption onto the magnetite surfaces was used to capture and remove arsenic impurities from water.

CREDIT: YAVUZ ET AL.




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