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Huang B.,Hunan University | Huang B.,Guangdong Provincial Key Laboratory of Atmospheric environment and Pollution Control | Zhu Y.,Hunan University | Li J.,Hunan University | And 2 more authors.
Electrochimica Acta | Year: 2017

The relationship between electrocatalysis and molecular electrochemistry for the reductive dechlorination of organic chlorides has been a central topic for decades. Herein, we try to reveal the catalytic property of silver electrode by investigating the thermodynamics of dissociative electron transfer (DET) to C–Cl bonds of polychloroethanes (PCAs) on both inert (GC) and catalytic (Ag) electrodes. By extending the “sticky” DET model reported by Savéant, we show that the catalyzed DET model can well describe the activation-driving force relationships for the electrocatalytic dechlorination on Ag, where in addition to the possible ion-dipole interations, the adsorption of chlorinated species onto Ag surface, which is found to play a fundamental role in the electrocatalysis process in this study, is introduced in the new developed DET model. In this work, we firstly report that the catalytic property of Ag electrode characterizing with drastically postive shift of reduction potential is ascribed to the lower of intrinsic barrier free energy, rather than the activation free energy, for the reductive dechlorination. Moreover, the intrinsic relationship of electrocatalysis and molecular electrochemistry is clearly indicated and quantitatively developed. These results may provide new insights in uncovering both the nature of catalytic property of Ag and the relationship of electrocatalysis and molecular electrochemistry for PCAs and other halocarbons. © 2017 Elsevier Ltd


Wu X.,Tsinghua University | Wu X.,Dongfeng Peugeot Citroen Automobile Co. | Liang J.,Tsinghua University | Wu Y.,Tsinghua University | And 4 more authors.
RSC Advances | Year: 2017

In the current study, Dunaliella tertiolecta (D. tertiolecta) and polypropylene (PP) were chosen to investigate the co-liquefaction process of microalgae and plastic. The results show that a maximum synergistic effect was found when the mass ratio of D. tertiolecta to PP was 8 : 2. The addition of PP mainly impacts the composition of the bio-oil products, particularly reducing the acid content. When D. tertiolecta was liquefied individually, the relative content of acid in bio-oil could reach 18.73%, while for D. tertiolecta and PP co-liquefaction in a ratio of 8 : 2, the acid content of bio-oil was lower than the detection limit of GC-MS (lower than 100 ppm). The reaction mechanism for the co-liquefaction process of PP and the main components of microalgae has also been studied. The addition of PP has a significant effect on the transformation pathways of carbohydrates in microalgae, and this also promotes the Maillard reaction between carbohydrates and proteins or their hydrolysates. © The Royal Society of Chemistry.


Zhang Q.,Kunming University of Science and Technology | Zhang Q.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control | Xu L.,Kunming University of Science and Technology | Ning P.,Kunming University of Science and Technology | And 2 more authors.
Applied Surface Science | Year: 2014

A series of CuO-CeO2-ZrO2 catalysts were prepared by different methods and applied to the selective catalytic reduction of NO with NH3 reaction at low temperature. The results showed that the SCR activities, morphology, particles dimension, and the surface chemical state of CuO-CeO2-ZrO2 catalysts were obviously influenced by the preparation method. The SCR performance results showed that the CuO-CeO2-ZrO2 catalyst prepared by co-precipitation method presented the best activity in the temperature range of 125-180 °C. The characterization results showed that the Ce4+, Ce3+, Cu2+ and Cu+ species were coexistence in the CuO-CeO2-ZrO2 catalysts, and the Cu species mainly existed as Cu2+. It was also found that the high surface area, the synergistic effect between copper and ceria, enhanced acidity and the highly dispersed copper species were responsible for the high SCR activity of the CuO-CeO2-ZrO2 catalyst. © 2014 Elsevier B.V. All rights reserved.


Zhang Q.,Kunming University of Science and Technology | Zhang Q.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control | Song Z.,Kunming University of Science and Technology | Ning P.,Kunming University of Science and Technology | And 3 more authors.
Catalysis Communications | Year: 2014

A series of acid modified CeO2 catalysts were prepared and used for selective catalytic reduction (SCR) of NO with NH3. The results showed that the SCR activity of pure CeO2 was greatly enhanced by the modification of acid. The CeO2 modified by 20% phosphotungstic acid exhibited the best NO conversion in a wide temperature range of 150-550 °C. The SCR activity was slightly influenced by SO2 and H2O, while such effect was reversible. The improvement of SCR activity and N2 selectivity over CeO2 catalyst modified by acid was attributed to the enhanced amount and intensity of Brønsted or Lewis acid sites. © 2014 Elsevier B.V. All rights reserved.


Guo X.,South China University of Technology | Yang C.,South China University of Technology | Yang C.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control | Dang Z.,South China University of Technology | And 4 more authors.
Chemical Engineering Journal | Year: 2013

In order to understand the sorption processes of tylosin (TYL) and sulfamethazine (SMT) on soils, the sorption thermodynamics and kinetics properties of two chemicals on goethite were investigated through sorption equilibrium and sorption rate experiments. The results showed that the sorption of TYL and SMT were nonlinear and the sorption capacities were influenced by the pH conditions of solution. The sorption rates for TYL and SMT decreased as the initial concentration increased. The sorption process might be constituted with the initial boundary layer diffusion or external surface, then the intraparticle diffusion or pore diffusion stage and finally equilibrium stage related with the sorption on the interior surface of sorbent. Thermodynamic calculations of sorption of TYL and SMT on goethite revealed that the sorption of TYL on goethite was exothermal and spontaneous and SMT was endothermic and spontaneous. The results indicated that the transportation abilities of TYL and SMT might be weak for the soils rich in iron oxide. The significant differences in the sorption behavior of two chemicals might be related with their physicochemical properties and suggested that the sorption mechanisms of TYL and SMT on goethite would be complicated and the domain sorption mechanism for each chemical at different pH conditions would be variable. It should be noted to assess the environmental risks of TYL and SMT. © 2013 Published by Elsevier B.V.


Liang H.-Y.,South China University of Technology | Zhang Y.-Q.,South China University of Technology | Zhang Y.-Q.,Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology | Zhang Y.-Q.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters | And 3 more authors.
Chemical Engineering Journal | Year: 2013

Oxidation of p-chloroaniline (PCA) by persulfate (PS) performed with a novel supported copper oxidate catalyst in an aqueous solution at ambient temperature (i.e. 20°C) was investigated in this study. This study focused mainly on determining the proportions of heterogeneous catalysis in the copper oxidate/PS combined system. There existed a more remarkable effect on the degradation of PCA in the copper oxidate/PS combined system than in the Cu2+/PS or only PS system. The effects of copper oxidate dosage, persulfate concentration, and initial solution pH on the oxidation of PCA were also evaluated. Higher copper oxidate dosage and persulfate concentration resulted in higher PCA degrading rates, the optimal initial pH was determined as 7.0. Moreover, the change in the degradation of PCA by pH was also investigated in terms of the contribution of dissolved copper ion in leaching solution. We inferred that homogeneous catalysis was of increasing importance and the copper ion dissolved from the copper oxidate was regarded as the key factor activating the persulfate under acidic conditions (pH 3.0), heterogeneous catalysis played the main role in the oxidation of PCA at pH 5-7. However, both heterogeneous catalysis and base-activated persulfate contributed to the degradation of PCA under alkaline conditions (pH 11). In addition, the radical mechanism was studied and three radical scavengers (phenol, methanol (MA) and Tert-butanol (TBA)) were used to determine the kind of major active areas taking part in the PCA degradation at pH 7. © 2012 Elsevier B.V.


Li L.,Guangdong Power Grid Corporation | Wang L.,South China University of Technology | Wang L.,U.S. National Center for Atmospheric Research | Pan S.,Guangdong Power Grid Corporation | And 4 more authors.
Cuihua Xuebao/Chinese Journal of Catalysis | Year: 2013

A series of manganese and cerium oxides supported on multi-walled carbon nanotubes (MWCNTs) catalysts for low-temperature NH3 selective catalytic reduction (SCR) of NOx were prepared by the pore volume impregnation method. The SCR activity of Mn-Ce/MWCNTs catalysts was compared with that of Mn/MWCNTs catalyst. The effects of Ce were characterized by transmission electron microscopy, N2 adsorption-desorption, H2 temperature-programmed reduction, X-ray photoelectron spectroscopy and X-ray powder diffraction. The results show that the addition of ce-rium oxides could improve the SCR activity of Mn/MWCNTs catalysts. Mn-Ce/MWCNTs catalyst with a Ce/Mn ratio of 0.6 was found to have the highest activity. The addition of cerium oxides enhanced the dispersion of metal oxides on the MWCNTs. It could also increase the specific surface area and total pore volume, and decrease the average pore size of the catalysts. Ce would improve the concentration of oxygen and the valence of manganese. Furthermore, from the XRD results, it was obvious that the crystalline MnOx disappeared because of the introduction of Ce to the catalyst. MnOx mainly existed in an amorphous state or microcrystal structure in the Mn-Ce/MWCNTs catalysts. CeO2 was found to be the main phase for CeOx. © 2013, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.


Peng D.,South China University of Technology | Peng D.,Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters | Lan Z.,South China University of Technology | Lan Z.,Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters | And 7 more authors.
Bioresource Technology | Year: 2013

In this work, a new biotechnological procedure was developed using cellulase as a modifier to produce oil sorbent from corn stalk (CMCS). Cellulase treatment of raw corn stalk (RCS) with enzyme loading of 100 U/g at 45 °C for 6 h resulted in high oil sorption capacity. The sorption capacities of vegetable oil, diesel and crude oil by CMCS were 18.47, 16.15 and 27.23 g/g, respectively, which were found to be much higher than RCS. XRD, BET and SEM were applied to characterize RCS and CMCS. The effects of sorbent dose (0.1-0.5 g), initial oil amount (5-30 g), and the sorption kinetics were also studied. This work demonstrated that corn stalk modified by cellulase is an efficient and environment-friendly biosorbent for the removal of spilled oil. © 2013 Elsevier Ltd.


Hussain I.,South China University of Technology | Zhang Y.,South China University of Technology | Zhang Y.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control | Huang S.,South China University of Technology | Huang S.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control
RSC Advances | Year: 2014

Zero valent iron (ZVI) can activate persulfate to generate sulfate free radicals which are a strong oxidant to degrade organic pollutants. The oxidative degradation of aniline in aqueous solution by persulfate activated with zero valent iron was studied under laboratory conditions. Batch experiments were conducted to investigate the effects of different parameters such as pH, ZVI concentration, aniline concentration, persulfate concentration and reaction temperature on aniline degradation. The results showed that aniline degradation increased with increasing temperature. The optimum dosage of ZVI was 0.4 g L-1 and 85% aniline degradation was observed. Maximum aniline degradation was observed at pH 4.0, whereas at pH above or below 4.0, aniline degradation efficiency was decreased. In the persulfate-ZVI system, the apparent energy of activation for aniline degradation was 14.85 kJ mol-1. The existence of persulfate radicals and hydroxyl radicals produced during the degradation of aniline were identified with scavenger ethanol and tert-butyl alcohol. The reaction intermediates nitrobenzene, nitroso-benzene and p-benzoquinone were detected by gas chromatography-mass spectrometry and based on these intermediates obtained a probable pathway for aniline degradation has been proposed.


Lin J.-M.,South China University of Technology | Fu M.-L.,South China University of Technology | Fu M.-L.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control | Zhu W.-B.,South China University of Technology | And 3 more authors.
Journal of Molecular Catalysis | Year: 2014

Citric acid complex method and coprecipitation method were utilized for the preparation of MnOx(0.4)-CeO2 catalysts towards model soot oxidation. The structure properties and surface reactive species on the catalysts were characterized by XRD, BET, Raman, H2-TPR, O2-TPD and XPS. The soot catalytic oxidation mechanism was investigated by in situ Raman spectra. The results showed that MnOx(0.4)-CeO2-CA catalyst synthesized with citric acid complex method, with more Mn ions incorporated into the ceria lattice, possessed larger specific surface area, more oxygen vacancies, Mn4+ and Ce4+. Thus, MnOx(0.4)-CeO2-CA exhibited better redox properties and higher soot oxidation activities. O- was found to play a key role in soot oxidation. Mn4+ and Ce4+ favored to the redox reaction, and the increase of oxygen vacancies were propitious to the adsorption, migration and transformation of oxygen species, boosting soot oxidation. The reaction path was O- spilled from the catalyst and reacted with soot firstly, oxygen vacancy was formed simultaneously, and then part of the lattice oxygen O2- replenish the consumed O-. Gaseous oxygen O2 adsorbed to the oxygen vacancy and activated to O2 -, and then changed to O-(can transformed to O2- in the further step), O- migrated to the soot surface and oxidizes it very efficiently in the next cycle, CO2 was formed subsequently.

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