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Mechanochemistry, a technique concerning with milling contaminated samples for prolonged times, induces massive degradation of pollutants by grinding them in ball mills with different soil components or additives. In the present study, laboratory experiments were conducted to evaluate the effect of aging on the mechanochemical efficiency of the Mn-oxide birnessite in degrading pentachlorophenol (PCP). A comparative study on an aged birnessite (KBiA), used after 3 years from synthesis, and a fresh birnessite (KBiF), employed immediately after synthesis, was carried out. The differences between the two birnessites, evidenced by spectroscopic and diffractometric techniques, are mainly relative to reduction of the Mn(IV) centered at the MnO6 octahedra layers from the birnessite structure, which represent the most reactive sites for PCP degradation. The long term air drying at room temperature, by favouring reduction of Mn(IV) to Mn(III), produces an inorganic substrate that offers paucity of the less reactive sites for PCP degradation, thus reducing the oxidative potential of the KBiA. Accordingly, the more reactive fresh birnessite was employed in the experiment with a polluted soil. Adding a small amount of KBiF to soil only induces a light increase in PCP removal, probably due to the mechanically induced PCP adsorption and transformation onto clay minerals present in the soil. Besides, adding a higher dose of birnessite causes a stronger degradation of PCP. 相似文献
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Shu Saeki Junya Kano Fumio Saito Kaoru Shimme Seiichi Masuda Tsuyoshi Inoue 《Journal of Material Cycles and Waste Management》2001,3(1):20-23
Polyvinyl chloride (–CH2–CHCl–)
n
(PVC) was ground with a powdered inorganic material (CaO, CaCO3, SiO2, Al2O3, or slag) in a planetary ball mill under atmospheric conditions to investigate the effect of additions on its dechlorination.
The grinding causes a dehydrochlorinating reaction, forming a mixture of partially dechlorinated PVC and inorganic chloride,
depending on the grinding time. The dechlorination increases as the grinding progresses, and is improved with increasing amounts
of additives. The most effective additive is a mixture of CaO, SiO2, and Al2O3, which has the same constituent components as blast furnace slag. CaO, a mixture of CaO, SiO2, and blast furnace slag, are also effective, but CaCO3 is the least effective additive tired.
Received: August 3, 2000 / Accepted: September 21, 2000 相似文献
3.
Lead halide perovskites MAPbX3 (MA = CH3NH3 or Cs; X = I, Br, Cl) are well considered to be potential candidates for photocatalytic reaction due to its excellent photoelectrical properties, but they still suffer from the low charge separation efficiency and slow catalytic reaction dynamics. To tackle the drawbacks, herein, MAPbBr3/carbon sphere (CS) composite photocatalysts using glucose as the carbon source were elaborately designed and fabricated via a dry mechanochemical grinding process. The interfacial interaction Pb-O-C chemical bonds were constructed between MAPbBr3 and the carbon sphere surface containing organic functional groups. By optimizing the content of CSs, the enhanced photocatalytic degradation kinetic rate of Malachite Green (MG) pollutants (92% within 20 min) for MAPbBr3/CSx (x = 17 wt.%) is about 3.6-fold of that for pristine MAPbBr3, which is attributed to the corporative adsorption and enhanced carrier transportation and separation of MAPbBr3/CSx. Furthermore, the possible degradation mechanism was proposed on basis of the electrochemical, mass spectrometry and optical characterization results. Owing to the robust interfacial interaction, effective electron extraction rate (ket = 4.6 × 107 sec?1) from MAPbBr3 to CS can be established, which driven oxygen activation where superoxide radicals (?O2?) played an important role in MG degradation. It is expected that mechanochemistry strategy may provide a new route to design efficient lead halide perovskite-carbon or metal oxide or sulfide composite photocatalysts. 相似文献
4.
Mohammadtaghi Vakili Wen Qiu Giovanni Cagnetta Jun Huang Gang Yu 《Frontiers of Environmental Science & Engineering》2021,15(6):128
5.
Mechanochemistry of ibuprofen pharmaceutical 总被引:1,自引:0,他引:1
In this paper mechanochemistry has been studied in view of possible application to detoxification of expired pharmaceuticals. The experiments have been carried out with a commercial medication containing ibuprofen ((RS)-2-(4-(2-methylpropyl)phenyl)propanoic acid) which has been submitted to prolonged milling up to 40 h. When Al(OH)3 is used as co-reagent, the first degradation step induced by the mechanochemical treatment is an acid-base reaction with the ibuprofen carboxylic acid group. The subsequent degradation follows a complex pathway leading to 1-(4-isobutylphenyl)ethanone, 1-isobutyl-4-vinylbenzene and 2-(4-(3-methylbutan-2-yl)phenyl)propan-1-ol after 10 h milling and, in addition, 1-(4-acetylphenyl)-2-methylpropan-1-one, 1-(4-(1-hydroxy-2-methylpropyl)phenyl)ethanone and 1-(4-(2-hydroxy-2-methylpropyl)phenyl)ethanone after 40 h milling. The degradation reaction path and products have been identified by means of FT-IR spectroscopy, thin layer chromatography, NMR spectroscopy, mass spectroscopy and elemental analysis. The observed ibuprofen decarboxylation makes the drug simultaneously lose both its pharmaceutical activity and toxicity. 相似文献
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