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Yang S.,CAS Qingdao Institute of Oceanology | Yang S.,Ocean University of China | Yang S.,Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering MEGE | Li L.,Ocean University of China | And 4 more authors.
Applied Surface Science | Year: 2016

A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N2 adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the -NO2 has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment. © 2016 Elsevier B.V.


Shen D.,Nanjing Southeast University | Hu J.,Nanjing Southeast University | Xiao R.,Nanjing Southeast University | Zhang H.,Nanjing Southeast University | And 2 more authors.
Bioresource Technology | Year: 2013

Thermogravimetric-Mass Spectroscopy (TG-MS) study on lignin decomposition under different (oxygen-containing) atmospheres was carried out to investigate thermal performance of lignin during pyrolysis, oxidative gasification, oxy/fuel combustion and CO2 gasification. Only one significant mass loss stage was observed for lignin decomposition under helium (He), while another stage, representing char oxidation, appeared under oxygen and CO2 conditions. No significant variation of the activation energy was presented for the first pyrolysis stage under different atmospheres (from 40.4 to 53.2kJ/mol). A much higher temperature was required for char oxidation under CO2 than those under O2 atmospheres, giving the activation energy of 541.9kJ/mol as compared to around 160kJ/mol for O2-containing atmospheres. The evolution profiles of CO and CO2 under different atmospheres were in good accordance with the DTG curves regardless of atmospheres. © 2012 Elsevier Ltd.


Meng W.,Wuhan University of Technology | Meng L.,Wuhan University of Technology | Chen C.Z.,China City Environment Protection Engineering Ltd Company
Advanced Materials Research | Year: 2014

With the development of power electronics technology, a variety of unbalanced load are connected to the grid, causing the grid voltage imbalance and power quality decline, seriously affect the user's normal use. Traditional three-leg inverter can output three-phase symmetrical voltage in the case of three-phase symmetrical load. But it is difficult to output three-phase symmetrical voltage when the three-phase load is asymmetric. In order to solve the impact of unbalanced load on the power quality, the three-phase four-leg inverter which is obtained with the addition of a bridge arm on the basis of traditional three-leg inverter is adopted in this paper. Therefore, the three-phase symmetrical voltage can be acquired in the case of unbalanced load, at the same time, with the advantages of simple structure, small size, light weight, higher voltage utilization. © (2014) Trans Tech Publications, Switzerland.


Yang S.,CAS Qingdao Institute of Oceanology | Yang S.,Shandong Provincial Key Laboratory of Marine Environment | Yang S.,Ocean University of China | Li L.,CAS Qingdao Institute of Oceanology | And 7 more authors.
Separation and Purification Technology | Year: 2016

Ammonia modified cotton-based activated carbon (AC-NH3) was prepared and utilized to investigate the effect of ammonia modification on the chemical properties of activated carbon in catalyzed peroxymonosulfate (PMS) oxidation of aqueous organic pollutant. Activated carbons with and without modification were characterized by N2 adsorption/desorption, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Boehm titration, Fourier Transform Infrared Reflection (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. Results indicated that ammonia modification has a promoting effect on the catalytic ability of AC in our system. And as small amount as 0.04 g/L AC-NH3 can efficiently activate PMS and subsequently degrade a model contaminant, Reactive Black 5 (RB5). Considering RB5 was barely removed by sole-AC-NH3 or sole-PMS, adsorption and catalytic oxidation have a significant synergistic effect in the combined AC-NH3/PMS system. With the XPS spectra deconvolution, we inferred that the π-π and pyrrolic functional groups resulted in the promoting catalytic ability of AC-NH3. However, the pyridine seems to play a nonsignificant role in our process. In addition, the parameters in the AC-NH3/PMS system, including the mole ratio of PMS to RB5, the dosage of AC-NH3, the initial concentration of RB5, initial pH, and the feeding method of PMS, were also discussed. © 2016 Elsevier B.V. All rights reserved.


Feng D.,China City Environment Protection Engineering Ltd Company | He J.,Huazhong University of Science and Technology | Xia S.,Huazhong University of Science and Technology | Chen L.,Huazhong University of Science and Technology | And 3 more authors.
IEEE Transactions on Plasma Science | Year: 2015

In the process of electromagnetic launch, the nonuniform contact pressure distribution on the armature-rail interface kept changing with the armature moving forward. At first, the contact pressure was mainly provided by the deformation of the trailing arm, from which it could keep a good metal-metal contact at the armature-rail interface. After the pulse current was constructed, the magnetic pressure would dominate the contact pressure because it was much larger than the mechanical interference pressure. In this paper, the 3-D modeling of contact pressure distribution was carried out with the finite-element method. In the simulation of 3-D contact calculations, the current entered the armature from the trailing edge. The electromagnetic force perpendicular to the armature trailing arm was equivalent to the uniform load on the inner surface of the trailing arm. A typical contour pattern of nonuniform contact pressure distribution was acquired. Some nonuniform coefficients of contact pressure distribution were proposed and analyzed to evaluate the contact performances between the armature and rails. A series of simulations was conducted at different magnitudes of magnetic pressure, and with different armature structure parameters. The characteristics of the nonuniform coefficients were investigated and discussed. The dependences of the nonuniform coefficients on the equivalent uniform load and armature structure parameters were obtained. © 1973-2012 IEEE.


Feng D.,China City Environment Protection Engineering Ltd. Co. | Xia S.,Huazhong University of Science and Technology | Chen L.,Huazhong University of Science and Technology | Tang L.,Huazhong University of Science and Technology | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2015

To improve the design of C-shaped monolithic armatures used in rectangular-bore railguns, we studied the non-uniformity of contact pressure distribution in armature assembly based on numerical simulation. The simulation was conducted using the finite element analysis software ABAQUS to calculate the pressure distribution on the contact surface between assembled armature and rail in static state. The simulation verifies the non-uniformity of the contact pressure distribution. On the basis of the contour pattern of pressure distribution, we proposed four coefficients to represent the non-uniformity of transvers-direction, launch-direction, overall, and local contact pressure distributions, respectively. All of these coefficients range between 0~1, and the higher their values are, the more non-uniform the corresponding distributions are. Based on further calculation, we also obtained the relation between these coefficients and some basic structural parameters of armature: the four coefficients are barely influenced by the interference of armature, decrease with increasing the tail length, increase with increasing the bulk depth, but vary in different pattern with increasing the rear radial depth. ©, 2015, Science Press. All right reserved.


Chang Q.,Wuhan University of Science and Technology | Li X.,China City Environment Protection Engineering Ltd Company | Ni H.,Wuhan University of Science and Technology | Zhu W.,China City Environment Protection Engineering Ltd Company | And 2 more authors.
ISIJ International | Year: 2015

Lots of iron molten slag from blast furnace can be produced during iron making process. It is generally cooled by water quenching method which causes many problems, such as water consumption, serious pollution, energy wasting etc. To solve these problems, much more attention has been paid to various dry granulation methods. Among them, dry centrifugal granulation (DCG) method has its own advantages. In this study, a physical and mathematical model of slag flow behavior in DCG process is established. The DCG process with a flat disc at different mass flow rate, temperature or viscosity, surface tension of molten slag, rotating speed and surface roughness of disc is simulated. The influences of various factors on granulation process are analyzed and optimum parameters are obtained. The results show that the granulation can be greatly improved by increasing the rotating speed of the disc and by reducing the molten slag viscosity properly. Copyright © 2015. ISIJ.


Nie X.-B.,Changsha University of Science and Technology | Nie X.-B.,Xi'an University of Architecture and Technology | Li Z.-H.,Changsha University of Science and Technology | Ding L.-J.,China City Environment Protection Engineering Ltd Company | Huang T.-L.,Xi'an University of Architecture and Technology
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2016

Recently, the leakage risk for copepods is becoming a challenging problem for drinking water plants in China. In order to prevent drinking water distribution systems from copepods' efflux, the control of copepods with traditional drinking water treatment processes was investigated by using Harpacticoida as a research subject. More attention was paid to the relationship between the removal of Harpacticoida and morphological characteristics of flocs in a coagulation tank, and distribution of Harpacticoida in a sand filter bed. The results showed that high removal efficiency of 99% was obtained under the optimum operational conditions, which includes fast stirring of 300 r/min (1 min), moderate stirring of 150 r/min (5 min) and slow stirring of 75 r/min (5 min), polymeric aluminium chloride dosage of 10 mg/L, sedimentation time of 0.5 h, filtration rate of 9 m/h, and filtration cycle of 1d. The removal efficiency of coagulation on Harpacticoida was mainly determined by the effective adsorption of Harpacticoida onto flocs, and the larger particle size and the lower fractal dimension of flocs, the higher removal efficiency of Harpacticoida. During filtration, the passive migration of Harpacticoida in a sand filter bed, primarily induced by scouring and carrying of filtration flow, was the major factor resulting in copepods' efflux eventually. Therefore, high removal efficiency would be promised by decreasing the filtration rate and shortening the filtration cycle, because such operations could limit passive migration scale of Harpacticoida. © 2016, Chinese Society for Environmental Sciences. All right reserved.


Li S.-F.,China City Environment Protection Engineering Ltd Company | Fang M.-X.,Zhejiang University | Li X.-W.,Zhejiang University
Ranshao Kexue Yu Jishu/Journal of Combustion Science and Technology | Year: 2012

Thermogravimetric analysis was carried out to study the pressurized combustion characteristics of multigeneration semi-coke in Cahn TherMax 500, focusing on the influence of pressure on thermogravimetry, ignition, pyrolytic property, combustion stability, burn out and general combustion characteristics of semi-coke. The experimental results indicate that the combustion characteristics of semi-coke are improved significantly with the increase of pressure. When pressure increases from ordinary pressure to 2.4, MPa, ignition temperature decreases from 666°C to 523°C, while the pyrolytic property releasing index r, combustion instability index RW and general combustion index S increase from 0.115, 10.7 and 0.49 to 0.590, 33.2 and 2.83, respectively.


Zhang H.,Hubei Engineering University | Wu X.,Hubei Engineering University | Wu X.,Yangtze University | Li X.,Hubei Engineering University | Li X.,China City Environment Protection Engineering Ltd Company
Chemical Engineering Journal | Year: 2012

COD removal by oxidation as well as by coagulation during Fered-Fenton treatment of landfill leachate was quantitatively determined in this study. The effects of operating conditions such as H 2O 2 to Fe 2+ mole ratio, Fenton's reagent dosage, initial pH, current density, inter-electrode gap and hydrogen peroxide feeding mode on COD removal was investigated. The results showed that COD removal by oxidation is dominant due to the high H 2O 2/Fe 2+ mole ratio employed and the overall COD removal showed the same behavior as oxidation removal. The coagulation removal of COD increased with initial pH and ferrous iron dosage, but it was independent of current density and the inter-electrode gap at a fixed initial pH value and ferrous iron dose. Increasing Fenton's reagent dosage or decreasing the initial pH is likely to promote COD removal by oxidation. There existed an optimal H 2O 2/Fe 2+ mole ratio, current density or inter-electrode gap to reach the highest COD removal efficiency by oxidation. The stepwise or continuous addition of hydrogen peroxide was more effective to oxidize organics than a single dose of hydrogen peroxide. Nearly all the organic compounds (>4kDa) were degraded into smaller ones after Fered-Fenton treatment. GC-MS analysis was used to determine the organic compounds before and after the treatment. © 2012 Elsevier B.V.

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