Papers by Keyword: N

Abstract: In this paper, gas sensing property of a nitrogen doped ZnO was studied. nanofilms of pure and nitrogen-doped ZnO (0.1, 0.2 and 0.3 normality) were prepared on glass substrate by spray pyrolysis technique. These films were fired at 450°C for two hours in air atmosphere. nanobehavior of the films was confirmed by XRD and SEM analysis. Gas sensing behavior of the films was tested in static gas sensing system. Films were exposed to different gases as LPG.NH3, NO2, Ethanol vapour and CO2 at different ppm concentrations and different operating temperatures. Pure ZnO films showed poor sensing behavior. At 150°C, films of N-doped ZnO (0.3 normality) showed good sensing for Ethanol vapours. The gas sensitivity was determined as 86.8% for 200 ppm of Ethanol vapours. When compared with pure ZnO, the nitrogen doped ZnO films possessed more oxygen deficient species. Due to this crystal defects arising from nitrogen doping, the improvement in gas sensing property of ZnO may be argued. Keywords: Spray pyrolysis; ZnO; N; XRD; SEM; LPG

Abstract: This study was conducted in order to determine the suitable formula in developing a nanofiltration membrane using additive from kenaf core. Kenaf core was processed and analyse the suitable component to be used as the additive in formulation the nanofiltration membrane. Kenaf taken from National Kenaf and Tobacco Board (NKTB) Malaysia with code reference of V36 was used in this study. Cellulose of Kenaf core was extracted using Microcrystalline Cellulose (MCC) process at the Forestry Research Institute of Malaysia (FRIM). From few percentage of Kenaf cellulose with analyses using Flux Purewater Test, NaCl Test (Rejection Test), Molecular Weight Cut Off (MWCO) Test, Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FTIR), the suitable percentage of Kenaf cellulose for nanofiltration flat sheet membrane was obtained.

Abstract: Aeration was one of the common techniques which were focused in environmental engineering research. In this study, experiments were carried out to investigate the effect of aeration on nitrogen (N) fractions and its transformation in the sediment-water interface from urban lake. In addition, we measured the dehydrogenase (DHA) and Chla content in surface sediment to detect the changes of the microbial activity. The aim is to explore the regulation of N migration and transformation in the water-sediment interface during the treatment work of lake pollution. By mechanical aeration, we control the DO content of the overlying water at the range of 1.2-1.5 kg/L, 2.5-4.5 mg/L and 6.1-6.2 mg/L. Results showed that DO in overlying water play a role to the variation of N in water-sediment interface. NH₄⁺-N was the mainly N fraction released from sediment, the lower DO concentration (1.2-1.5 mg/L) in overlying water is favorable to the release of NH₄⁺-N from sediment. Whether under aerobic or anaerobic condition, the releasing of NH₄⁺-N from sediment were both higher than its consumption in the overlying water. The benthic microbial activity of the surface sediment (0-2 cm) was higher than that from bottom (6-8 cm). And the microbial activity in surface sediment was in optimum range when the overlying water DO content was about 2.5-4.5 mg/L.

Abstract: Soil microbial properties have been proved to be powerful indicators of soil quality. This study analyzed the changes in soil moisture content, soil bulk density and porosity, soil organic carbon, total nitrogen, and microbial biomass of Substrate in vegetation restoration of Rock Slope. The results showed that soil moisture, soil porosity, organic carbon (OC), total nitrogen (TN) and microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and C/N increased significantly, and soil bulk density decreased gradually compared with bare rock Slope. Therefore, the results suggested that the vegetation restoration of Rock Slope could improve soil quality.

Abstract: By low-temperature epitaxial growth of group IV semiconductors utilizing electron-cyclotron-resonance (ECR) plasma enhanced chemical vapor deposition (CVD), atomically controlled plasma processing has been developed in order to achieve atomic-layer doping and heterostructure formation with nanometer-order thickness control as well as smooth and abrupt interfaces. In this paper, typical recent progress in plasma processing is reviewed as follows: (1) By N and B atomic-layer formation and subsequent Si epitaxial growth on Si(100) without substrate heating, heavy atomic-layer doping was demonstrated. Most of the incorporated N or B atoms can be confined in about a 2-nm-thick region of the atomic-layer doped Si film. (2) Using an 84 % relaxed Ge buffer layer formed on Si(100) by ECR plasma enhanced CVD, formation of a B-doped highly strained Si film with nanometer-order thickness was achieved and hole mobility enhancement as high as about 3 was observed in the highly strained Si film.

Abstract: TiO2 photocatalyst modified by N and Fe ions was loaded on self-made fly ash forming adsorbent (FFA) using the sol-gel dip-coating process. The crystal structure and photoadsorption ability was characterized by X-ray diffraction (XRD) and UV-Vis spectrophotometer, respectively. The photo catalytic degradation of Reactive Brilliant Blue KN-R using N, Fe-TiO2/FFA was examined. Effects of initial dye concentration, pH value and hydrogen peroxide dosage on degradation were studied. The degradation of the organic molecule followed a pseudo-first-order kinetics according to the Langmuir model. Under the optimum operation conditions, 30 mg/L KN-R could be decolorized over 97.47% within 75 min.

Abstract: Electrochemical double layer capacitors (EDLCs) are promising high power energy sources for many different applications where high power density, high cycle efficiency and long cycle life are needed. However, because the energy density of EDLCs is small compared to that of rechargeable batteries one needs to increase the capacitance of EDLCs. The nanofiber diameters range from 50 nm to 400 nm, depending on the concentration of polymer solution types, tip-to-collector distance, applied voltage, and viscosity of the solution. The main advantage of the electrospinning process is that it is a simple means to prepare continuous fibers with unusually large surface to volume ratios and pore structure surfaces. So, feature of nanofiber webs are the high specific surface area developed by creating pores on the nanofiber surface. In this work, the multiwalled carbon nanotubes embedded polyacrylonitrile solutions in N,N-dimethylformamide (DMF) were electrospun to be webs consisting of 350 nm ultrafine nanofibers, which were used to produce a series of activated carbon nanofibers with developed mesoporosity and high electrical conductivity through stabilization, carbonization-activation processes.