Kunzan Qiu

Facile Preparation of Nickel Nanoparticle-Modified Carbon Nanotubes with Application as a Nonenzymatic Electrochemical Glucose Sensor

ABSTRACT A one-step synthesis for the incorporation of nickel nanoparticles on carbon nanotubes is reported using thermal annealing with NiCl2 and melamine. The morphology and structure of the nickel nanoparticle modified carbon nanotubes were characterized by transmission electron microscopy, scanning electron microscopy, and powder X-ray diffraction. X-ray photoelectron spectroscopy demonstrated that the nickel nanoparticles were on the surface of carbon nanotubes forming a robust structure. The nickel nanoparticle modified carbon nanotubes rapidly oxidized glucose in alkaline solution with an excellent stability. Consequently, the modified carbon nanotubes were shown to be a suitable enzyme-free glucose electrochemical sensor when attached to a glassy carbon electrode, with excellent long term stability, a short response time, a low limit of detection, a long linear dynamic range, high sensitivity, and good precision.

Note: Rapid reduction of graphene oxide paper by glow discharge plasma

This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application.

A novel method of microwave heating mixed liquid-assisted regeneration of V2O5–WO3/TiO2 commercial SCR catalysts

AbstractnAn experimental study on the regeneration of deactivated SCR catalysts was carried out using a microwave-assisted method containing three steps of washing with mixed liquid of ethanol and water, impregnating, and drying. After the regeneration treatment, NO conversion at 320xa0°C increased from 39 to 90xa0% and vanadium content increased by 62.2xa0%, which were much higher than those regenerated by the traditional method. The more impregnated vanadium was due to the fact that the rapid evaporation of mixed liquid inside the catalyst channels led to the enlargement of surface areas by creating more pores on the catalysts. Meanwhile, with the increasing concentrations of ethanol, the heating rate of the mixed liquid increased, and the volume after complete evaporation of the mixed liquid was gradually reduced. Since higher heating rate and lager volume after the liquid evaporation could help to create more pores, therefore, when the volume ratio of ethanol/mixed solution was 20xa0%, the catalyst obtained the maximum specific surface area, which significantly increased to ca. 123xa0% compared with the deactivated catalyst. In addition, the catalyst dried by microwave exhibited better catalytic activity than that dried in conventional oven. Therefore, this method showed great potential in industrial applications.

To characterize two-phase flows around a finned tube using the three-dimensional particle dynamics analyzer (PDA) and numerical calculation

Abstract By using a new type of laser measuring instrument, the three-dimensional particle dynamics analyzer (PDA), the characteristics of gas-solids two-phase flows around a single finned tube are measured. The parameters such as slip velocity and turbulent intensity are analyzed. The fluid field and particle movements are also numerically calculated through SIMPLE cells and the two-equation κ-ϵ model combined with the FSRT (fluctuation spectrum random trajectory) model of turbulence to simulate the turbulent fluid phase. The experimental and numerical calculation results are essentially identical. The results are very useful in guiding the design and structure optimization of gas-solid inertial separators with enhanced heat transfer unit finned tubes.

Experimental study on ZnO-TiO2 sorbents for the removal of elemental mercury

ZnO-TiO2 sorbents synthesized by an impregnation method were characterized through XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy) and EDS (Energy dispersive spectrometer) analyses. An experiment concerning the adsorption of Hg0 by ZnO-TiO2 under a simulated fuel gas atmosphere was then conducted in a bench-scale fixed-bed reactor. The effects of ZnO loading amounts and reaction temperatures on Hg0 removal performance were analyzed. The results showed that ZnO-TiO2 sorbents exhibited excellent Hg0 removal capacity in the presence of H2S at 150 °C and 200 °C; 95.2% and 91.2% of Hg0 was removed, respectively, under the experimental conditions. There are two possible causes for the H2S reacting on the surface of ZnO-TiO2: (1) H2S directly reacted with ZnO to form ZnS, (2) H2S was oxidized to elemental sulfur (Sad) by means of active oxygen on the sorbent surface, and then Sad provided active absorption sites for Hg0 to form HgS. This study identifies three reasons why higher temperatures limit mercury removal. First, the reaction between Hg0 and H2S is inhibited at high temperatures. Second, HgS, as the resulting product in the reaction of mercury removal, becomes unstable at high temperatures. Third, the desulfurization reaction strengthens at higher temperatures, and it is likely that H2S directly reacts with ZnO, thus decreasing the Sad on the sorbent surfaces.

Combining Fuel Rich/Lean Burner With the Small Heavy Oil Gun Ignition Techniques Makes Pulverized Coal-Fired Boiler More Efficient

The coal qualities changes very frequently in China, to make the flame stability under different operating conditions is difficult and it is important to prevent the furnace from the serious slagging while the coals with low ash fusion temperature are combusted, at the same time, the utility units now face the frequent load changing, how to save the oil at the low load or during the start up period becomes a very serious problem. In this work, the burner combing the fuel rich/lean separator and the small heavy oil gun ignition techniques were developed and then employed in a utility boiler. The detailed design of such a novel burner is introduced in this paper. Such a burner can achieve a 50% rated load and 70% heavy oil can be saved.Copyright

On‐line Electromagnetic Wave Based Coal Concentration Monitoring Technique for Pipe Flow

The on‐line coal concentration measuring technique for pipe gas‐solid flow is helpful for boiler operation optimization. In this work, a novel electromagnetic wave based coal concentration monitoring technology was developed. The monitoring system consists of an emitting antenna and a receiving antenna. The emitting antenna emits electromagnetic wave, the wave propagates in the coal pipe, and the amplitude of the electromagnetic wave is attenuated by the coal particles. The frequency of the electromagnetic wave can be adjusted to meet the diameter of the coal pipe. The electromagnetic wave motivates current in the receiving antenna, which is amplified by a multiplier and then acquisitioned by the computer. After the digital signal processing, the coal concentration of the gas‐solid pipe flow can be achieved. The results show that the electromagnetic wave based coal concentration measuring technology can give the on‐line solid concentration information, the output voltage is in linear relationship with the...

Experimental Investigations on Performance of Collision‐block‐type Concentrator Using Fiber Optic Probe

The concentrating performance of a collision‐block‐type fuel rich/lean burner was experimentally investigated using a fiber optic measurement system in a two‐phase‐flow test facility of internal diameter 150 mm. The local solid concentration and particle size distributions were measured to investigate the separation performance of the fuel‐rich/lean separator, also the mixing performance of the parallel fuel‐rich and fuel‐lean streams. The solid concentration of 0.42 kg/kg was employed in the experiments to investigate the influences of solid concentration on the concentrating performance of the separator. The measurements indicated that the collision‐block‐type separator always gave good concentrating performance under various inflow solid concentrations. The fuel‐rich and fuel‐lean streams do not mix together soon after leaving the burner, this leads to better ignition and combustion characteristics of the pulverized coal compared with the ordinary burner.