科研之友
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摘要
Nano zero-valent Iron(nZVI) has been widely used in water pollution treatment. The preparation method of nZVI with high purity and good dispersion has always been a research focus. In this paper, alcohols with different numbers of hydroxyl groups were used as modifiers, including ethanol, ethylene glycol, erythritol, mannitol and sorbitol, to prepare nZVI-EA, nZVI-EG, nZVI-ER, nZVI-M and nZVI-S sample, respectively. The above samples were applied to the reduction and removal of microcystin(Microcystin-LR, MC-LR) in water. The results showed that with the increase of hydroxyl groups, the antioxidant capacity and dispersity of modified nZVI were enhanced, and the degradation rate of MC-LR was also increased. The surface -area -normalized rate coefficient of nZVI-M(79.35x 10-5 Lmiddotm-2middotmin-1) was 9.3 times that of nZVI-S(8.55x10-5 Lmiddotm-2middotmin-1) and 61.0 times that of nZVI0(unmodified sample, 1.30x10-5 Lmiddotm-2middotmin-1). It was found by X-ray diffraction(XRD), energy dispersive spectroscopy(EDS) and potassium dichromate titration that this may be due to the highest Fe0 purity of nZVI-M(total iron content is 83.5%). In order to reveal the modification mechanism, the preparation process of nZVI-M was observed by optical microscope. It was found that transparent rod -like mannitol crystal clusters formed on the surface of Fe0, which improved the antioxidant capacity and dispersion of nZVI in water, and realized the efficient degradation of MC-LR. Unlike the hydroxyl group of sorbitol, the hydroxyl group of mannitol has a "jagged" distribution and its O2p orbital is prone to electron delocalization to form strong coordination with Fe3+. This will provide a new way to obtain nZVI with high purity and good dispersion by the coordination of alcohol hydroxyl groups.
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单位中国科学院
