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金虫 (职业作家)

[交流] 【NatureChina】Nanowaste: Reduce, reuse, recycle

http://www.nature.com/nchina/200 ... china.2008.164.html
Nanomaterials are often used to adsorb and remove toxic heavy metal and organic pollutants from industrial waste, but there remains the problem of disposing of the resulting 'nanowaste'. Zhang Lin at the Chinese Academy of Sciences in Fuzhou and co-workers1 have found a way of separating heavy metals from nanowaste and recycling some of the resulting products.

The sodium and potassium chlorate industries produce magnesium hydroxide nanowastes that are highly alkaline and frequently contain heavily oxidized chromium. The nanowastes are complex in composition, and therefore do not respond to common methods of separation, such as washing, centrifugation or filtration.

The researchers successfully separated the chromium from the nanowaste by adding a mineralizer and heating the waste until solid crystals formed. The best mineralizer was found to be a mix of sodium carbonate and sodium bicarbonate, which formed the largest and most stable crystals at a temperature of 180 °C (pictured).

This procedure, which has successfully been carried out on a large scale, releases the carcinogenic chromium into solution. The metal can later be reused in the chlorate industries. In addition, the non-toxic powder made up of micrometre-sized crystals can be recycled in other industries, such as ceramics, paints, plastics and lubricants.

The authors of this work are from:
State Key Lab of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, China; National Center for Nanoscience and Technology, Beijing, China.

Reference
Liu, W. et al. Treatment of CrVI-containing Mg(OH)2 nanowaste. Angew. Chem. Int. Ed. doi: 10.1002/anie.200800172 (2008).  | Article |
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