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Rubing ZhangLian Gao 《Materials Research Bulletin》2002,37(9):1659-1666
Nanosized titania particles, with typical particle sizes in the range of 30-50 nm have been synthesized using a microemulsion-mediated process. In this process, the aqueous cores of microemulsions have been used as constrained microreactors for the precipitation of titania precursor. The microemulsion was provided by a functionalized surfactant derived from the commercially available mixtures of sorbitol monooleate and polysorbate 80 (abbreviated as Span-Tween 80). The hydroxide particles, produced by the hydrolysis of the titanium tetraisopropoxide in the water droplets containing surfactant, were separated, dried, and calcined to form nanoparticles of TiO2. The dependence of the size of the precipitated TiO2 particles on various structure parameters of the microemulsion was studied in detail. 相似文献
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《Materials Letters》2007,61(4-5):1056-1059
A new method for synthesis of nanocrystalline titanium nitride was developed through the reaction of titanium oxide and sodium amide at 500–600 °C for 12 h in an autoclave. X-ray diffraction (XRD) and electron diffraction (SAED) results indicated the product had a cubic phase with lattice parameter a = 4.242 Å. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) revealed that the particle sizes were 10 to 40 nm. Quantitative analysis using X-ray photoelectron spectrum (XPS) showed the atomic ratio Ti:N was 1.03:1. 相似文献
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Rajesh J. Tayade Praveen K. Surolia Ramchandra G. Kulkarni 《Science and Technology of Advanced Materials》2013,14(6):455-462
Nanocrystalline TiO2 was synthesized by controlled hydrolysis of titanium tetraisopropoxide. The anatase phase was converted to rutile phase by thermal treatment at 1023 K for 11 h. The catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier-transform infrared absorption spectrophotometry (FT-IR) and N2 adsorption (BET) at 77 K. This study compare the photocatalytic activity of the anatase and rutile phases of nanocrystalline TiO2 for the degradation of acetophenone, nitrobenzene, methylene blue and malachite green present in aqueous solutions. The initial rate of degradation was calculated to compare the photocatalytic activity of anatase and rutile nanocrystalline TiO2 for the degradation of different substances under ultraviolet light irradiation. The higher photocatalytic activity was obtained in anatase phase TiO2 for the degradation of all substances as compared with rutile phase. It is concluded that the higher photocatalytic activity in anatase TiO2 is due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst. 相似文献
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Photocatalytic degradation of dyes and organic contaminants in water using nanocrystalline anatase and rutile TiO2 总被引:1,自引:0,他引:1
Rajesh J. Tayade Praveen K. Surolia Ramchandra G. Kulkarni Raksh V. Jasra 《Science and Technology of Advanced Materials》2007,8(6):455-462
Nanocrystalline TiO2 was synthesized by controlled hydrolysis of titanium tetraisopropoxide. The anatase phase was converted to rutile phase by thermal treatment at 1023 K for 11 h. The catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier-transform infrared absorption spectrophotometry (FT-IR) and N2 adsorption (BET) at 77 K. This study compare the photocatalytic activity of the anatase and rutile phases of nanocrystalline TiO2 for the degradation of acetophenone, nitrobenzene, methylene blue and malachite green present in aqueous solutions. The initial rate of degradation was calculated to compare the photocatalytic activity of anatase and rutile nanocrystalline TiO2 for the degradation of different substances under ultraviolet light irradiation. The higher photocatalytic activity was obtained in anatase phase TiO2 for the degradation of all substances as compared with rutile phase. It is concluded that the higher photocatalytic activity in anatase TiO2 is due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst. 相似文献
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Longhai Zhuo Kaichang Kou Yiqun Wang Pan Yao Guanglei Wu 《Journal of Materials Science》2014,49(14):5141-5150
We report the design and synthesis of a novel pyridine-containing triamine monomer, 2,6-bis(4-aminophenyl)-4-(4-aminophenoxy)pyridine (BAAP), through combining the nucleophilic aromatic substitution with modified Chichibabin reaction and hydrazine hydrate reduction. Based on it, a novel three-step route was applied in order to obtain a series of new polyimides, containing phthalimide as pendent group and pyridine moieties in main chains. The three-step route consisted of terminating the triamine by incorporating phthalic amic acid as pendant, ring-opening polymerization to form poly(amic acid)s and further chemical imidization to acquire polyimides. Nuclear Magnetic Resonance Spectroscopy (1H-NMR) was used for chemical structural characterization, and the results indicated the various forms of BAAP and branched structure units in the obtained polyimides. The morphology structures of the polyimides were evaluated by X-ray diffraction patterns, and the d-spacing values were found in the range of 4.14–4.65 ?. Most of the resulting polyimides were soluble in polar aprotic solvents, such as NMP, DMF, DMAc, DMSO, and so on. Meanwhile, the polyimides exhibited excellent thermal stability, with the decomposition temperature at 5 and 10 % weight loss temperatures in the ranges of 399.1–461.1 °C and 481.1–566.9 °C, respectively. The polyimides, based on 6FDA, possessed the best comprehensive thermally stable and soluble performance. 相似文献
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采用自动固相萃取法预处理,用气相色谱-质谱仪测定有机磷农药。最低检出限在0.10~0.30mg/L之间,水样加标回收率为75%~105%,样品经5次重复测定后相对标准偏差均小于6.0%。结果表明,该法具有简单、快速、准确的特点。 相似文献
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Fisseha R Dommen J Sax M Paulsen D Kalberer M Maurer R Höfler F Weingartner E Baltensperger U 《Analytical chemistry》2004,76(22):6535-6540
Organic acids in the gas and aerosol phase from photooxidation of 1,3,5-trimethylbenzene in the presence of 300 ppb propene and 300 ppb NOx in smog chamber experiments were determined using a wet effluent diffusion denuder/aerosol collector coupled to ion chromatography (IC) with conductivity detection. Behind the IC, the samples were collected using a fraction collector, for identification of unresolved/unidentified organic acids with IC-mass spectrometry (MS). In total, 20 organic acids were found with MS of which 10 were identified. The organic acids identified offline by IC-MS were then further quantified based on the online IC data. The identification was additionally confirmed with gas chromatography-mass spectrometry. At the maximum aerosol concentration, organic acids comprised 20-45% of the total aerosol mass. The method has a detection limit of 10-100 ng/m3 for the identified carboxylic acids. 相似文献
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Mehran Rezaei Seyed Mahdi Alavi Saeed Sahebdelfar Liu Xinmei Zi-Feng Yan 《Journal of Materials Science》2007,42(17):7086-7092
Mesoporous nanocrystalline zirconia with high surface area and pure tetragonal crystallite phase has been prepared by bifunctional
ethylene diamine as both precipitating agent for ZrO(NO3)2 to ZrO(OH)2 and colloidal protecting agent for the ZrO(OH)2 nanoparticles. The effect of refluxing time and temperature on the structural properties of the zirconia were investigated.
The obtained results showed that the increasing in refluxing time and temperature improved the thermal stability and increased
the tetragonal content of the zirconia. The results also showed that the addition of Pluronic P123 block copolymer surfactant
acted as a cosurfactant and increased the specific surface area of the zirconia. 相似文献
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本文采用固相萃取法预处理,然后用带有火焰光度检测器(FPD)的气相色谱仪测定有机磷农药。结果表明,该法具有简单、快速、准确的持点。 相似文献
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A simple and efficient headspace solvent microextraction (HSME) was developed for the simultaneous determination of the trace concentrations of some n-alkanes in water samples. Therefore, a microdrop of an organic solvent was extruded from the needle tip of a gas chromatographic syringe to the headspace above the surface of the solution in a sealed vial. Then the volatile organic compounds are extracted and concentrated in the microdrop. Next, the microdrop was retracted into the microsyringe and injected directly into the gas chromatograph. Experimental parameters which control the performance of HSME such as the type of microextraction solvent, organic drop and sample volume, sample stirring rate, sample solution and microsyringe needle temperatures, salt addition and exposure time profiles were investigated and optimized. Finally, the enrichment factor, dynamic linear range (DLR), limit of detection (LOD) and precision of the method were evaluated. Using optimum extraction conditions, good linearity with correlation coefficients in the range of 0.995相似文献
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《Advanced Powder Technology》2020,31(3):986-992
Different titanium oxide nanoparticles were formed through pulsed discharge of Ti wires in distilled water and H2O2 solution. The recovered samples were characterized by various techniques, such as XRD, SEM and TEM. The results confirm the presence of various titanium oxide nanoparticles including TiO2 phases (anatase and rutile) and various nonstoichiometric TiO2−x in recovered samples owing to the oxygen deficient circumstance through pulsed discharge. The titanium oxide nanoparticles exhibit a spherical shape with a size of 10–300 nm. The results show that the energy input adjusted by charging voltage is one major factor to control the phases of titanium oxide and the overall oxygen content of recovered samples. In addition, the H2O2 content in distilled water also affects the oxygen content of recovered samples. The sample recovered from 10% H2O2 solution is pure TiO2 consisting of anatase and rutile without nonstoichiometric TiO2−x. Moreover, the UV–Vis absorption spectra of recovered samples show their intensive visible light absorption and the correlation between the visible light absorption and the experimental conditions (charging voltage and H2O2 content). 相似文献
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Determination of tetraethyllead and inorganic lead in water by solid phase microextraction/gas chromatography 总被引:1,自引:0,他引:1
A new method for the determination of tetraethyllead (TEL) and ionic lead in water by SPME has been developed. TEL is extracted from the headspace over the sample. Inorganic lead is first derivatized with sodium tetraethylborate to form TEL, which is extracted in the same way as pure TEL samples. The analytical procedure was optimized with respect to pH, amount of derivatizing reagent added, stirring conditions, and extraction time. The detection limit obtained for TEL was found to be 100 ppt when using FID and 5 ppt when using ion trap MS (ITMS). The detection limit for Pb(2+), limited by the nonzero blank, was found to be 200 ppt. Linear calibration curves were obtained for both analytes when FID was used for detection. For lead they spanned over 4 orders of magnitude. ITMS offered excellent sensitivity and selectivity, but the calibration curves were nonlinear when the m/z = 295 ion was used for quantitation. The method has been verified on spiked tap water samples. An excellent agreement was found between the results obtained for standard solutions prepared using NANOpure water and spiked tap water samples. 相似文献
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The potential of gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC/TOF-MS) for screening of organic pollutants in water has been explored. After optimization of the solid-phase microextraction (SPME) step, where parameters such as fiber selection and addition of salt were studied, this extraction technique was applied to the analysis of different types of water samples. Investigation of 60 target organic pollutants, including pesticides, octyl/nonyl phenols, pentachlorobenzene, and polycyclic aromatic hydrocarbons (PAHs) was carried out by evaluating the presence of up to five representative m/z ions per analyte, measured at high mass accuracy, and the attainment of their Q/q (Q, quantitative ion; q, confirmative ion) intensity ratio. This strategy led to the detection of 4-t-octylphenol, simazine, terbuthylazine, chlorpyrifos, terbumeton, and terbutryn in several water samples at low part-per-billion levels. Full spectrum acquisition data generated by the TOF-MS analyzer also allowed subsequent investigation of the presence of polybrominated diphenyl ethers and several fungicides in samples after MS data acquisition, without the need to reanalyze the water samples. In addition, nontarget analysis was also tested by application of a deconvolution software. Several organic pollutants that did not form a part of the list of contaminants investigated were identified in the water samples, thanks to the excellent sensitivity of TOF-MS in full spectrum acquisition mode and the valuable accurate mass information provided by instrument. Bisphenol A, the antioxidant 3,5-di-tert-butyl-4-hydroxy-toluene (BHT), its metabolite 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO), the polycyclic musk galaxolide, and the UV filter benzophenone were some of the compounds present in the water samples analyzed. SPME in combination with GC/TOF-MS has been proved to be an attractive and powerful approach for the rapid screening of multiclass organic pollutants in water, with very little sample manipulation and no solvent consumption. This combination provides to the analyst with information-rich MS data that facilitates the reliable identification of many different organic compounds in samples. 相似文献