Papers by Keyword: Ethanol Sensor

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Authors: Niyom Hongsith, Supab Choopun
Abstract: Platinum impregnated ZnO tetrapods were prepared and studied for the detection of ethanol vapor. ZnO tetrapods were synthesized by oxidation reaction technique by heating a mixer of zinc powder (99.99%) and hydrogen peroxide solution (30 wt.%) at 1,000oC in air. Platinum was impregnated by dropping hydrogen hexachloroplatinate (IV) hydrate, H2Cl6Pt.aq, solution with different concentration on ZnO tetrapods and then, heated at 350oC for 1 hr. The platinum impregnated ZnO tetrapods were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) for morphology and chemical composition, respectively. The particles were observed on the surface of ZnO tetrapods. The EDS spectrum suggested that the particles were platinum. Platinum impregnated ZnO tetrapods were tested ethanol sensing properties under ethanol concentration of 50-1,000 ppm. The ethanol sensing results indicated that the sensitivity of the sensors depended on the platinum impregnated concentration. Moreover, the sensors based on platinum impregnated ZnO tetrapods of 0.035 wt.% exhibited higher sensitivity compare to those of non-impregnation ZnO tetrapods.
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Authors: E. Wongrat, P. Pimpang, N. Mangkorntong, Supab Choopun
Abstract: ZnO nanostructures were synthesized by thermal oxidation reaction from zinc powder and then impregnated by gold colloid. The gold colloid was prepared by chemical reduction technique and had red color. The heating temperature and sintering time of thermal oxidation were 700 °C and 24 hours, respectively under oxygen atmosphere. The morphology of ZnO nanostructures and ZnO impregnated gold colloid were studied by field emission scanning electron microscope (FE-SEM). The diameter and length of pure ZnO and ZnO impregnated gold colloid were about the same value and were in the range of 100-500 nm and 2.0-7.0 µm, respectively. The ethanol sensing properties of ZnO impregnated by gold colloid were tested in ethanol atmosphere at ethanol concentrations of 1000 ppm and at an operating temperature of 260-360 °C. It was found that the sensitivity and response time were improved for gold impregnated sensor with an optimum operating temperature of 300°C due to the enhanced reaction between the ethanol and the adsorbed oxygen at an optimum temperature.
293
Authors: Yun Lin Dai, Zhong Cao, Yi Min Dai, Ju Lan Zeng, Wei Gang Huang, Jing Ling Hu, De Liang He, Katsuyuki Aoki
Abstract: Coating with a calixarene derivative on gold surface of AT-cut quartz crystal, a piezoelectric quartz crystal (PQC) sensing device was successfully fabricated in this paper. Among four calixarene materials, the compound of MRCT was the most efficient actively coating material for recognizing ethanol molecule based on a host-guest recognition mechanism with C—H•••π interaction. In comparison with gas-chromatography (GC) method, the calixarene based PQC device can be well used for on-line detection of the ethanol vapor in the range of 0 ~ 3000 ppm around our environment with a recovery of 92.33~105.76 %. The detection limit can be evaluated to be 3.53 ppm. Furthermore, the proposed TSM sensor possessed good selectivity, reproducibility, reversibility and high stability for practical purpose.
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Authors: Won-Woo Baek, Dong Won Shin, Sang Tae Lee, Jeong Ok Lim, Jeung Soo Huh
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Authors: Hasnida Saad, Mohd Tarmizi Ali, M. Kamil Abd Rahman
Abstract: This paper presents the preparation of intensity-based plastic optical fiber (POF) sensor and its characteristics in the detection of ethanol concentration in water. Response of the sensor probes were analyzed for 0.02 to 1.00% v/v ethanol concentrations. The POF sensors have high sensitivity of detecting very low concentration of ethanol with 0.02% v/v ethanol in water. The reponsitivity of the polished U-shape sensor was 285 per percent of ethanol concentration. There are three distinct shapes of POF sensor probes that were developed: tapered U-shape; polished U-shape; and polished coil-shape. The POF were shaped into sensor probes by indirectly heating the POF at 80°C for several minutes and rapidly cooled in retaining the shapes. Tapering of POF was done using tensile tester with thermostatic chamber and other sensor probes were polished using fine abrasive for enhancing their sensitivities. The performance of the sensors was tested using He-Ne laser as the light source and the output spectra were analyzed using Ocean Optics spectrometer. The light intensity from the three sensors showed nonlinear response to ethanol concentrations from 0.02% - 1.00%. The POF sensor is more sensitive to 0.02%-0.10% ethanol concentration compared to 0.20% to 1.00%. At lower concentration, water tends to gradually absorb into POF polymer network and causes the fiber to swell more due to volume expansion. Higher ethanol concentration causes the swelling of the fiber to be eventually reduced and reached its detection limit.
693
Authors: Jiang Ying Li, Bao Juan Xi, Jun Pan, Yi Tai Qian
Abstract: Urchin-like CuO, consisting of closely packed nanorods with a diameter of 10nm, have been successfully synthesized by a poly(ethylene glycol) (PEG)-assisted hydrothermal route at low temperature of 100°C. The as-obtained Urchin-like CuO were thoroughly characterized by X-ray diffraction (XRD) study, Field emission scanning electron microscope (FESEM), High-resolution transmission electron microscopy (HRTEM) and Gas sensor measurements. From the XRD pattern, all the peaks detected can be assigned to CuO in a monoclinic structure with lattice parameters a=4.662, b=3.416 and c=5.118 (JCPDS card no. 65-2309). The FESEM and TEM showed that the diameter of the urchin-like CuO sphere is about 1µm. Further investigation of the formation mechanism reveals that the PEG-assisted hydrothermal process is vital to the formation of 3D structures. Besides the template function, PEG often plays as a reductant while reacting with Cu(+2). In our case, no impurity peaks of Cu2O were observed in the XRD pattern, implying that PEG did not reduce Cu(+2) to Cu(+1). We attribute this to the high concentration of PEG. The sensor based on the urchin-like CuO nanostructures exhibit excellent ethanol-sensing properties at reduced working temperature (200°C), which shows a sensitivity two times higher than that of CuO particles(about 100nm, made from calcinations of Cu(NO3)2 at 400°C). The enhancement in sensitivity of the as-prepared CuO may be contributed to the fancy 3D nanostructures.
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