The oxidation of antimony (III) in soils was studied using X-ray absorption fine structure (XAFS) spectra. An andosol soil sample and artificial soil samples (SiO2 blended with iron (III) hydroxide and manganese (IV) oxide) were used herein. After adding antimony (III) oxide to all soil samples, the oxidation process was observed by recording the XAFS spectra of Sb K-edge, Fe K-edge, and Mn K-edge. The results indicated that manganese (IV) oxide played an important role in the oxidation of Sb(III); however iron (III) hydroxide was not directly related to the reaction. During a 2-hr continuous Sb K-edge X-ray absorption near edge structure (XANES) measurement with an interval of 1 min of one of the artificial soil samples (SiO2 + MnO2 + Sb2O3), a pseudo-first-order reaction was determined with an average estimated rate of 0.52 ± 0.04 hr? 1. Compared to the lower oxidation rate of andosol, it is suggested that because of the low concentration of Mn(IV) in natural soils, the oxidation process of Sb(III) might be relatively slow and require more time to convert Sb(III) to Sb(V). 相似文献
The Aliakmon River originates in the North Western part of Greece, traverses the Western part of Macedonia, and discharges into the Thermaikos Bay in the North Aegean Sea. Proton induced X-ray emission (PIXE) method with external beam was used for the determination of the metallic elements in the waters and sediments of the Aliakmon River. the pH, dissolved oxygen, conductivity, and total phosphate and nitrate concentrations were also monitored in the water samples. Data collected for a 20-month period indicate that the Aliakmon River can be still considered as an unpolluted river. 相似文献
We describe a new technique of local analysis of heterogeneous samples which is analogous to the electron or ion microprobe but is based on molecular spectra of materials to characterize the different components of a microscopic sample and (or) to obtain images giving their surface distribution. The sample is illuminated by a laser beam causing characteristic Raman lines of the different components to be emitted. Using these Raman lines, the components can then be detected, identified and located. For this purpose, the microscopic area of the preparation which is illuminated is analysed by a conventional optical microscope coupled with a tunable band pass filter and a multichannel or monochannel detection system. One main advantage of this technique is the ability to study samples not under vacuum but in air, under a controlled atmosphere or even inside a transparent matrix. Normal Raman spectra can be obtained from particles of 1 μm size and larger, and are the basis for the qualitative identification of molecular constituents. The technique has been applied to molecular microanalysis of matter in the particulate form (i.e., Airborne particles—stack particulates, flyash, asbestos minerals, defects and inclusions in industrial materials,...). It is especially interesting for organic materials which are not detected by other methods. Different examples illustrate this technique. 相似文献
Multi-walled carbon nanotubes (MWNTs) oxidized with sulfuric acid, nitric acid, and the mixture of sulfuric and nitric acids were characterized by thermogravimetric analysis (TGA), Raman spectroscopy, elemental analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. The TGA data showed that the MWNTs were more resistant to oxidation than C60 or activated carbon fibers. Catalyst particles could be removed by the oxidants containing sulfuric acid, and thus indicative of the tip opening of MWNTs. The sulfuric acid had a propensity to create defect sites and introduce the surface oxides at those defects that already exist or be newly generated on MWNTs. However, the acid mixture could open the caps of MWNTs but preserve the structure homogeneity. The treatment with nitric acid gave rise to the highest bulk oxygen content in MWNTs, while the most abundant surface oxides were provided by sulfuric acid oxidation. In addition, nitric acid exhibited the best ability to transform the phenolic groups into carboxyl groups. 相似文献
Bottom ash is an inevitable by-product from municipal solid waste (MSW) incineration plants. Recycling it as additives for cement production is a promising disposal method. However, the heavy metals and chlorine are the main limiting factors because of the potential environmental risks and corrosion of cement kilns. Therefore, investigating heavy metal and chlorine characteristics of bottom ash is the significant prerequisite of its reuse in cement industries. In this study, a correlative analysis was conducted to evaluate the effect of the MSW components and collection mode on the heavy metal and chlorine characteristics in bottom ash. The chemical speciation of insoluble chlorine was also investigated by synchrotron X-ray diffraction analysis. The results showed that industrial waste was the main source of heavy metals, especially Cr and Pb, in bottom ash. The higher contents of plastics and kitchen waste lead to the higher chlorine level (0.6 wt.%–0.7 wt.%) of the bottom ash. The insoluble chlorine in the MSW incineration bottom ash existed primarily as AlOCl, which was produced under the high temperature (1250°C) in incinerators.