Papers by Keyword: Ammonia

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Authors: Kao Wen Zhou, Zi Qiao Zhang, Li Jing Xing, Xin Li, Chun Xue Fu
Abstract: A new sensor based on cataluminescence (CTL) produced on the surface of nanosized TiW3Cr2O14 was demonstrated for direct determination of ammonia in air. Trace ammonia was firstly absorbed on active carbon at room temperature to concentrate, then desorbed at 105°C to determine. The sensor showed high selectivity to ammonia at wavelength of 540 nm, satisfying activity at temperature of 275°C and good stability at air carrier flow rate of 115 ml/min. The linear range of CTL intensity versus concentration of ammonia was 1.0~50 mg/m3 (γ=0.9990), and the detection limit (3σ) was 0.5 mg/m3. The recovery of artificial sample was 97.45%—102.73% by this method. There was no response to benzene, SO2, CO and formaldehyde, and insignificant response to ethanol. This gas sensor allows on-line monitoring of ammonia in air.
Authors: Hong Hong Yuan, Pei Dong Tai, Xiao Jun Li, Xiao Nan Yang
Abstract: Toxic data of local fishes was very essential in the derivation of local water quality criteria. In this study, two local fishes (S.dabryi and P.parva) of Liao River were chosen to conduct 96-h acute toxic data under ammonia (total ammonia) whose pollution was proved to be serious in Liao River. 96 h LC50s of S.dabryi and P.parva under total ammonia were 35.36 mg/L (pH=7.50, T=20.00°C) and 30.35 mg/L (pH=7.50, T=20.00°C), respectively. These toxic values could be used to supply the local database which was the basement to formulate site-specific water quality criteria accordingly in Liao River.
Authors: Jing Li, Dong Mei Jia, Chang Hai Li, Bao Qing Yu
Abstract: The ammonia modified cotton stalks (CS) were utilized to adsorb the Ni2+ and Cu2+ ions from wastewaters, and the effect parameters (i.e. pH, contact time, adsorbent dose, and temperature) were also investigated by batch adsorption experiments. The maximum uptake was attained, i.e., 99.4% and 98.8%, respectively, for nickel and copper ions, under the optimum conditions (adsorbent dose: 10 g/L; pH: 6.0 (Ni2+), 5.0 (Cu2+); t: 75min; T: 20 °C) when the initial concentration of heavy metal ions was 20 mg/L. The adsorption process of nickel and copper ions on ammonia modified CS was well described by the pseudo-second-order kinetic model.
Authors: Ivana Turekova, Zuzana Turňová, Martin Pastier
Abstract: Modern autonomous systems (AUS) correspond to the current global technical standards and European principles of prevention of industrial accidents. Their construction requires a purposeful and systematic approach of investors. The paper presents an elaborated standard project of an autonomous system with ammonia as a kind of refrigerant for an ice rink. The implementation of the proposed project can make the process of warning and alerting the population in danger more effective.
Authors: N.S. Zhu, S.N. Ma, C.H. Hu
Abstract: Low temperature ammonia plasma surface treatment on asphalt base carbon fiber is reported with 150°C for 60min, 200°C for 60min and without treatment. The surface topography, chemical composition and structural changes were followed by Atomic force microscope(AFM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, of which indicate the treatment could improve the density of carbonyl and amino functional group on the surface of carbon fiber, which can also changed carbon crystalline structure. The density of carbonyl and amino functional group was shown higher for the fibers treated at 150°C than for the fibers treated at 200°C which could be attributed to the temperature and introduced Si element factors.
Authors: Fumitaka Hayashi, Masakazu Iwamoto
Abstract: Mesoporous silicon oxynitride and nitride were prepared through nitridation of various mesoporous silica, MCM-41, -48, and SBA-15 with ammonia in a plug flow reactor. The nitrogen contents were dependent on the reaction temperature and the amount of ammonia supplied per sample weight. The appropriate nitridation temperature was 1273 K and the maximum contents of nitrogen were 35-39 wt % which correspond to 88-98% of that of Si3N4. Various physicochemical characterization of the resulting silicon (oxy)nitiride indicated that the pore structures were not changed upon the nitridation though the lattice constants and the pore diameters decreased and the wall thickness increased. The nitridation mechanism was discussed on the basis of 29Si MAS NMR and XPS experiments.
Authors: B. Armas, C. Combescure, M. De Icaza Herrera, Francois Sibieude
Authors: Li Rong Peng, Xing Hua Yang, Li Bo Yuan, En Ming Zhao, Le Li, Shen Zi Luo
Abstract: An optical ammonia probe was fabricated based on Microstructured Polymer Optical Fiber (MPOFs) modified by eosin doped silica gel films.The structure of this probe was based on microstructured polymer optical fibers with microholes and these microholes could be used as the substrate of sensing materials and minor reaction pools. The sensing properties of the optical fiber sensor to gaseous ammonia were investigated at room temperature. The sensing probe showed different fluorescence intensity at 576 nm to different concentrations of trace ammonia in carrier gas of nitrogen. The response range was 20-350 ppm, with short response time within 600 ms.
Authors: Xiao Lu Huang, Nan Tao Hu, Yan Yan Wang, Ya Fei Zhang
Abstract: Here we demonstrate a promising gas sensor based on aniline reduced graphene oxide (RGO), which is fabricated through drop drying RGO nanosheets suspension between the electrode arrays to create conductive networks. RGO, as the sensing materials, which is prepared via the chemical reduction of graphene oxide (GO) by aniline, has been characterized by infrared spectroscopy, UV-Vis spectroscopy, transmittance electron microscopy and scanning electron microscopy. The sensing properties of RGO have also been studied, and the results show that RGO reduced from aniline (RGO-A) exhibits an excellent response to ammonia gas (NH3). Comparing with the RGO reduced from hydrazine (RGO-H) and polyaniline (PANI) nanofiber, the RGO-A exhibits a much better response to NH3 gas. The response of the sensor based on RGO-A to 50 ppm NH3 gas exhibits about 9.2 times and 3.5 times higher than those of the device based RGO-H and PANI nanofiber respectively. In addition, the RGO-A sensor exhibits an excellent repeatability and selectivity to NH3 gas. The oxidized aniline, i.e., polyaniline, which is attached on the surface of RGO sheets through π–π interaction, plays important roles in the final sensing performance of the device, and benefits for the application of the sensor in the field of NH3 gas detection.
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