It has been shown that starch can effectively stabilize nanoscale magnetite particles, and starch-stabilized magnetite nanoparticles (SMNP) are promising for in situ remediation of arsenic-contaminated soils. However, a molecular level understanding has been lacking. Here, we carried out XAFS studies to bridge this knowledge gap. Fe K-edge XAFS spectra indicated that the Fe-O and Fe-Fe coordination numbers of SMNP were lower than those for bare magnetite particles, and these coordination numbers decreased with increasing starch concentration. The decrease in the average coordination number at elevated stabilizer concentration was attributed to the increase in the surface-to-volume ratio. Arsenic K-edge XAFS spectra indicated that adsorbed arsenate on SMNP consisted primarily of binuclear bidentate (BB) complexes and monodentate mononuclear (MM) complexes. More BB complexes (energetically more favorable) were observed at higher starch concentrations, indicating that SMNP not only offered greater adsorption surface area, but also stronger adsorption affinity toward arsenate. 相似文献
• An in situ electron-induced deNOx process with CNT activated by DBD was achieved.• Carbon atoms on CNT surface were verified to be excited by plasma in DBD-CNT system.• Reactions between NOx and excited C result in synergistic effect of DBD-CNT system. In this study, a new in situ electron-induced process is presented with carbon nanotubes (CNTs) as a reduction agent activated by dielectric barrier discharge (DBD) for nitrogen oxide (NOx) abatement at low temperature (<407 K). Compared with a single DBD system and a DBD system with activated carbon (DBD-AC), a DBD system with carbon nanotubes (DBD-CNT) showed a significant promotion of NOx removal efficiency and N2 selectivity. Although the O2 content was 10%, the NOx conversion and N2 selectivity in the DBD-CNT system still reached 64.9% and 81.9% at a specific input energy (SIE) of 1424 J/L, and these values decreased to 16.8%, 31.9% and 43.2%, 62.3% in the single DBD system and the DBD-AC system, respectively. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were utilized to investigate surface changes in the CNTs after activation by DBD to explore the NOx reduction abatement mechanism of this new process. Furthermore, the outlet gas components were also observed via Fourier transform infrared spectroscopy (FTIR) to help reveal the NOx reduction mechanism. Experimental results verified that carbon atoms excited by DBD and the structure of CNTs contributed to the synergistic activity of the DBD-CNT system. The new deNOx process was accomplished through in situ heterogenetic reduction reactions between the NOx and carbon atoms activated by the plasma on the CNTs. In addition, further results indicated that the new deNOx process exhibited acceptable SO2 tolerance and water resistance. 相似文献
AbstractMulti-spectroscopic and molecular docking methods were used to study the interaction between triclosan (TCS) and bovine serum albumin (BSA). The results indicated that the fluorescence quenching of BSA by TCS was due to the formation of TCS–BSA complex through static quenching. This result was also demonstrated by time-resolved fluorescence experiment. The binding constants and number of binding sites between TCS and BSA were 1.30?×?105 M?1 and 1.17 at 298?K, respectively. The thermodynamic parameters were studied in detail which suggested that hydrophobic forces and hydrogen bond played major roles in the TCS–BSA interaction. Moreover, the site marker competitive experiments and docking studies revealed that TCS could bind BSA into site I in subdomain IIA. All the results of UV–vis spectrophotometry, circular dichroism spectroscopy and synchronous fluorescence spectroscopy showed that interaction between TCS and BSA induced conformation changes of BSA. 相似文献
Environmental Science and Pollution Research - In this study, the immature mice were taken to assess the potential neurological toxicity of lead (Pb) and di (n-butyl) phthalates (DBP) combination... 相似文献
Efficient abatement of an iodinated X-ray contrast media iohexol by an emerging sulfite autoxidation advanced oxidation process is demonstrated, which is based on transition metal ion–catalyzed autoxidation of sulfite to form active oxidizing species. The efficacy of the combination of sulfite and transition metal ions (Ag(I), Mn(II), Co(II), Fe(II), Cu(II), Fe(III), or Ce(III)) was tested for iohexol abatement. Co(II) and Cu(II) are proven to show more pronounced catalytic activity than other metals at pH 8.0. According to the quenching studies, sulfate radical (SO4??) is identified to be the primary species for oxidation of iohexol. Increasing dosages of metal ion or sulfite and higher pH values are favorable for iohexol abatement. Inhibition of iohexol abatement is observed in the absence of dissolved oxygen, which is vital for the production of SO5?? and subsequent formation of SO4??. Overall, activation of sulfite to produce reactive radicals with extremely low Co(II) or Cu(II) concentrations (in the range of μg L?1) in circumneutral conditions is confirmed, which offers a potential SO4??-based advanced oxidation process in treatment of aquatic organic contaminants.
This paper is particularly related to elemental mercury (Hg0) oxidation and divalent mercury (Hg2+) reduction under simulated flue gas conditions in the presence of nitric oxide (NO) and sulfur dioxide (SO2). As a powerful oxidant and chlorinating reagent, Cl2 has the potential for Hg oxidation. However, the detailed mechanism for the interactions, especially among chlorine (Cl)-containing species, SO2, NO, as well as H2O, remains ambiguous. Research described in this paper therefore focused on the impacts of SO2 and NO on Hg0 oxidation and Hg2+ reduction with the intent of unraveling unrecognized interactions among Cl species, SO2, and NO most importantly in the presence of H2O. The experimental results demonstrated that SO2 and NO had pronounced inhibitory effects on Hg0 oxidation at high temperatures when H2O was also present in the gas blend. Such a demonstration was further confirmed by the reduction of Hg2+ back into its elemental form. Data revealed that SO2 and NO were capable of promoting homogeneous reduction of Hg2+ to Hg0 with H2O being present. However, the above inhibition or promotion disappeared under homogeneous conditions when H2O was removed from the gas blend. 相似文献
The denaturing gradient gel electrophoresis (DGGE) method was applied to determine the relative genetic complexity of microbial communities in flooded paddy soil treated with herbicide quinclorac (3,7-dichloro-8-quinoline-carboylic acid). The results obtained showed a significant effect of quinclorac on the development of bacterial populations in soils contaminated with different concentrations of the herbicide at the early time after application. In general, however, the number of populations of the same soil sample treated with the same concentration of the quinclorac differed obviously with increasing incubation time within the early 8 weeks. The scale of differences in banding patterns-showed that the microbial community structures of the quinclorac-treated and non-quinclorac-treated soils were not significantly different after 21 weeks of incubation. Quantification, as demonstrated in this paper, was studied by establishing dose-response relationships. Significant pattern variations were quantified. Prominent DGGE bands were excised, cloned and sequenced to gain insight into the identities of predominant bacterial populations. The majority of DGGE band sequences were related to bacterial genera Clostridium, Sphingobacterium, Xanthomonas and Rhodococcus. 相似文献