Publications by authors named "Chunan Ma"

The continuous solid solution NiWO is successfully prepared by using precursor WO with plenty of oxygen defects. The NiWO nanoparticles are characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray absorption spectroscopy. The crystallographic phase of NiWO is stable and characterized by the same feature of the parent lattice WO even with various concentrations of dopant Ni which indicates the existence of oxygen defects.

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In exploration of low-cost electrocatalysts for direct methanol fuel cells (DMFCs), Pt modified tungsten carbide (WC) materials are found to be great potential candidates for decreasing Pt usage whilst exhibiting satisfactory reactivity. In this work, the mechanisms, onset potentials and activity for electrooxidation of methanol were studied on a series of Pt-modified WC catalysts where the bare W-terminated WC(0001) substrate was employed. In the surface energy calculations of a series of Pt-modified WC models, we found that the feasible structures are mono- and bi-layer Pt-modified WCs.

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Surface-enhanced Raman scattering (SERS) of thiosalicylic acid (TSA) with sulfydryl group was investigated on the surface of electrochemically roughed silver electrode. The result shows that SERS enhancement effect was relative to the concentration and pH, and 1 x 10(-3) mol x L(-1) and pH 4 were the optimal condition. While the concentration increased, the enhancement effect decreased quickly because of steric hindrance.

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We developed a facile method to synthesize core-shell WC@meso-Pt nanocatalysts by carburizing ammonium tungstate and copper nitrate via gas-solid reactions, followed by a Pt replacement reaction. The mesoporous nanocomposite displays higher activity and stability towards methanol electrooxidation than commercial Pt/C catalysts.

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In this study, cross-linked chitosan microspheres (CCTS) was synthesized from chitosan and epichlorohydrin (ECH), then, 2-(chloromethyl) benzimidazole (CBM) was introduced to modify CCTS as the ligand. The resulting CBM-chitosan was characterized by EA, FTIR and TGA, and tested for metal adsorption. Results showed that CBM-chitosan has a relatively high selectivity toward Hg(2+).

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Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe(NO3)3 x 9H2O and Co(NO3)2 x 6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-(2,4-dichlorophenoxy)propionic acid (2,4-DP), nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance.

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To well describe the Ti(IV)-catalyzed H2O2/O3 reaction in aqueous solution, a kinetic model was established based on its mechanism. This model was then validated by the experiments of acetic acid degradation in aqueous solution. It was found that the correlation coefficient of fittings was higher than 0.

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The oxidation system of electrolysis coupled ozonation (electrolysis-ozonation) was used to degrade 4-chlorophenol (4-CP), and its mechanism was discussed on the basis of kinetic analysis. The experimental results indicated the electrolysis-ozonation system had a significant synergistic effect during degradation of 4-CP. For example, the electrolysis-ozonation had the 4-CP removal rate of 92.

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The presence of Fe(3)O(4)-CoO/Al(2)O(3) can improve degradation efficiency significantly during the ozonation of the herbicide 2-(2,4-dichlorophenoxy) propionic acid (2,4-DP). The main factors affecting degradation efficiency, such as pH, the catalyst concentration and addition of the scavenger, were investigated. The kinetics of the catalytic ozonation are also discussed.

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Two-component CuO-Ru based on active Al2O3 (CuO-Ru/Al2O3) catalyst was prepared by incipient wetness impregnation and used to catalytic ozonation of acetophenone (AP). The results showed that doping Ru could significantly improve the catalytic activity of CuO/Al2O3. For example, the COD removal rates of AP solution after 30 min by ozonation alone, CuO/Al2O3/O3, and CuO-Ru/Al2O3/O3 were 6.

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The complexation reactions of ethylenediaminetetraacetate (EDTA(4-)) and S,S-ethylenediaminedisuccinate (S,S-EDDS(4-)) with Co(2+), Ni(2+), Cu(2+), Zn(2+), and Cd(2+) cations are investigated by using the DFT/B3LYP method. The hydration reaction of each metal ion with solvent water cluster is considered with a mixed cluster/continuum model. The subsequent metal complexation is treated as a substitution reaction of the coordinated water molecules by the amino polycarboxylic acid ligand.

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The effect of ozonation of terephthalic acid (TA) was evaluated, and the kinetic and mechanism of this process were also discussed. The rate constants of TA with ozone and OH radicals calculated by the relative method are (0.047 +/- 0.

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Deactivation of Pt electrode in the process of electroxidation of p-chlorophenol (p-CP) was investigated using linear sweep voltammetry, LC/MS and spectrum analysis techniques. The experiment results indicated that Pt would lose its electro-catalytic activity soon because polymer formed at the electrode surface. The in-site IR spectra of Pt showed two weak absorption bands appeared at 1 200 and 1 800 cm(-1) during the oxidation of p-CP, which are characteristics of aromatic ether and carbonyl group, respectively.

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Cystine was indirectly determined by flame atomic absorption spectrometry with ZnS. Base on the determination mechanism, the composition of complex, the complex balance reaction of soluble zinc ion, which formed in the determination of cystine by FAAS, and the stability constant of complex balance were discussed in the present paper. Under the alkalescent conditions, cystine (Cys-Cys) can react with zinc sulfide suspension solution to form a soluble complex or chelate of zinc cystine.

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Nitrobenzene, glycolic acid and acetic acid were selected to be degraded by O3/UV. During the degradation of nitrobenzene by O3/ UV, addition of MnO2, an effective catalyst to decompose H2O2 in water, decreased the degradation efficiency obviously, and the degradation efficiency of O3 /UV was even lower than that of ozonation alone, for example, the TOC removal rates of nitrobenzene by O3 /UV, O3 and O3/UV + MnO2 were 44% , 41% and 39% in 40 minutes, respectively. These results demonstrate that intermediate H2O2 plays an important role in enhancement of degradation efficiency of O3/UV.

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The near-infrared laser Raman spectra influenced by environmental light were studied in the determination of sodium glutamic acid solution. The environmental lights included natural light from outdoors and light from room fluorescent lamp. The results show that different influences on near infrared laser Raman spectra of sodium glutamic acid solution can be produced in different environmental light.

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Many abnormal peaks in laser Raman spectra were found in determinations with laser illuminant of 785. 18 nm. After studies, it was found that the notch filter caused the interferences and the characteristics of the band pass filter were not good.

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A label free, reagentless aptasensor for adenosine is developed on an ISFET device. The separation of an aptamer/nucleic acid duplex by adenosine leads to the aptamer/adenosine complex that alters the gate potential of the ISFET. The sensitivity limit of the device is 5 x 10-5 M.

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The laser Raman spectra influenced by environmental light have been studied in the determination of sodium glutamic acid solution. The environmental light included natural light from outdoors and the light from indoor fluorescents. The results show that different influences on laser Raman spectra of sodium glutamic acid solution can be produced in different environmental light.

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The influences of different laser source and different light power on laser Raman spectra were studied for the sodium glutamic acid. The results show that some influences existed using different wavelength and power of light source the peak shifting 6 cm(-1). As UV laser has great light power, the samples were destroyed, making the Raman spectra- reduce or disappear.

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Each state of arginine and zinc ion in aqueous solution under different pH conditions was calculated by computer, giving out the scattergram. After the investigation, the mechanism of complexing action in indirectly determining arginine by flame atomic absorption spectrometry with ZnS was studied in terms of the influence of solution pH. It is with different state of arginine and zinc ion in aqueous solution in differential pH that the response peak with pH in given conditions is obtained.

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On the bases of exploring measurement mechanism and complex compound components of indirect determination of cysteine acid by flame atomic absorption spectrometry with zinc sulfide, the stability constants of the complex compound of zinc cysteinate were studied successfully, after the numeric measurements and theoretical investigations under the best optimized acidity for the determination. In conclusion, at the best optimized acidity pH 9.7, the stability constant of alkalescence zinc cysteinate is between 2.

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Dechlorination property of p-chlorophenol (p-CP) by Ni/Fe bimetallic particles was studied in this work. The experimental results show that adsorbed hydrogen atom is the main reductive agent for dechlorination of p-CP and chemical reaction at the surface of catalyst is the rate-determing step in this process. The catalyst with mass ratio of 2.

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Article Synopsis
  • Recent research highlights the persistent challenge of finding effective anodes that combine both activity and stability for electrochemical oxidation in treating organic wastewater.
  • A newly developed beta-PbO2 electrode, modified with fluorine resin, significantly extends the anode's lifespan to over 10 years under typical conditions, demonstrating selective degradation of various phenolic compounds.
  • The study identifies hydroxyl radicals as the primary active species responsible for the reaction with phenolic compounds, proposing a new electrochemical degradation mechanism that shows promise for environmental applications.
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