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101.
Phase diagrams for oil/methanol/ether mixtures 总被引:4,自引:4,他引:4
David G. B. Boocock Samir K. Konar Hanif Sidi 《Journal of the American Oil Chemists' Society》1996,73(10):1247-1251
One-phase transmethylations of vegetable oils with methanol to form methyl esters occur considerably faster than conventional
two-phase reactions. Addition of simple ethers is an efficient method for producing a single phase. Ternary phase diagrams
have been determined at 23°C for oil/methanol/ether mixtures; these are useful when applying the one-phase method across a
wide range of conditions. Soybean, canola, palm, and coconut oils were used in combination with five ethers, namely, tetrahydrofuran
(THF), 1,4-dioxane (DO), diethyl ether (DE), diisopropyl ether (DI), andtert-butyl methyl ether (TBM). All five ethers can produce miscibility for all methanol/oil compositions. The ether/methanol volumetric
ratios required for miscibility at a methanol/soybean or canola oil volumetric ratio of 0.20 (5.4 molar ratio) at 23°C are:
THF, 1.15; DO, 1.60; DE, 1.38 DI, 1.57; and TBM, 1.57. For THF, this results in one-phase mixtures that contain 65 vol% oil.
Soybean and canola oil form identical diagrams. Palm oil requires slightly less ether at the lower methanol concentrations,
but coconut oil requires considerably less across the whole concentration range. Acid-catalyzed reactions, when performed
at the boiling point of the most volatile component, require less ether than predicted from the diagrams. 相似文献
102.
Chemical composition and antioxidant properties of Laurus nobilis L. and Myrtus communis L. essential oils from Morocco and evaluation of their antimicrobial activity acting alone or in combined processes for food preservation 总被引:1,自引:0,他引:1 下载免费PDF全文
103.
104.
Alireza Samavati Zulkafli Othaman Sib Krishna Ghoshal Mohammad Reza Dousti Mohammed Rafiq Abdul Kadir 《International journal of molecular sciences》2012,13(10):12880-12889
The visible luminescence from Ge nanoparticles and nanocrystallites has generated interest due to the feasibility of tuning band gap by controlling the sizes. Germanium (Ge) quantum dots (QDs) with average diameter ~16 to 8 nm are synthesized by radio frequency magnetron sputtering under different growth conditions. These QDs with narrow size distribution and high density, characterized using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) are obtained under the optimal growth conditions of 400 °C substrate temperature, 100 W radio frequency powers and 10 Sccm Argon flow. The possibility of surface passivation and configuration of these dots are confirmed by elemental energy dispersive X-ray (EDX) analysis. The room temperature strong visible photoluminescence (PL) from such QDs suggests their potential application in optoelectronics. The sample grown at 400 °C in particular, shows three PL peaks at around ~2.95 eV, 3.34 eV and 4.36 eV attributed to the interaction between Ge, GeOx manifesting the possibility of the formation of core-shell structures. A red shift of ~0.11 eV in the PL peak is observed with decreasing substrate temperature. We assert that our easy and economic method is suitable for the large-scale production of Ge QDs useful in optoelectronic devices. 相似文献
105.
Rui Feng Hamid A. Al-Megren Zhanquan Zhang Mohammed C. Al-Kinany Zifeng Yan Zhongdong Zhang Xionghou Gao 《Journal of Porous Materials》2014,21(6):947-956
Interest in reducing SO2 emission from the fluid catalytic cracking (FCC) crude oil has been encouraging the development of new materials to achieve such goal. The nanostructured Mg–Al spinel (MgAl2O4) was prepared by co-precipitation and post hydrothermal treatment in the presence of glucose and followed by elimination of the organic components by calcination at 700 °C for 3 h. Physical and chemical properties were characterized by XRD, N2 sorption, TG, FTIR, SEM, and TEM methods. Mesoporous nanostructured MgAl2O4 with a high surface area of 324 m2 g?1 were obtained. The organic components contributed to the development of mesoporosity, functioning as a soft template. SO2 adsorption tests showed that the nanostructured MgAl2O4 had a 51.58 % increase of SO2 sorption capacity than MgAl2O4 prepared without glucose. These results showed that the nanostructured MgAl2O4 is a promising candidate as catalyst for flue gas desulfurization in FCC process. Three kinetic models were also applied to analyze the SO2 adsorption kinetics; the pseudo-second order kinetic model fit well with a correlation coefficient (R2) of 0.991 for nanostructured MgAl2O4. 相似文献
106.
107.
ABSTRACT The kinetics of ligand exchange between bulk solution TBP and uranyl nitrate bound TBP in o-xylene has been investigated by 31P dynamic NMR spectroscopy. First order ligand exchange rate constant, k, and the activation energy for the uranyl nitrate-TBP system were determined from plots of transverse relaxation rates (In (l/τ)) versus reciprocal temperature (1/T). Using the Eyring equation, the average values of activation enthalpy, δH* (30.8±5.1 kJ-mole?1), and activation entropy, δS* (-109±19 J/mol-K) have been calculated. The negative entropy of activation value indicates an increase in order on proceeding from the reactants to the activated complex. Therefore, an associative mechanism may be proposed for the ligand exchange reaction between UO2(NO3)2 TBP2 and TBP. Equilibration of the extractant phase with 1.0 M HC1 did not change the ligand exchange rate constants or the activation parameters appreciably. These results are discussed in comparison with previous reports on TBP exchange rates for this system. 相似文献
108.
Assem Barakat Mousa Al-Noaimi Mohammed Suleiman Abdullah S. Aldwayyan Belkheir Hammouti Taibi Ben Hadda Salim F. Haddad Ahmed Boshaala Ismail Warad 《International journal of molecular sciences》2013,14(12):23941-23954
[NiCl2(C14H12N2)(H2O)] complex has been synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM). 相似文献
109.
Mohammed Aider Djamel Djenane Wassef B. Ounis 《International Journal of Food Science & Technology》2012,47(5):1028-1036
Amino acid composition, protein hydrophobicity, foaming and emulsifying properties of mustard protein isolate at pH 3, 5, 7 and in 0.05 and 0.1 m NaCl were studied. Glutamic (19.18 ± 0.30%) and aspartic (7.49 ± 0.11%) acids were the dominants. Foaming ability was enhanced by NaCl. Time to reach 75 mL foam was 23% higher in water than in NaCl. Drained volume after 10 min was concentration dependent and was the lowest in 0.05 and 0.1 m NaCl at protein concentration of 2.5% and 5%. The emulsifying properties were pH and concentration dependent, and the best results were obtained at pH 3, corresponding to the highest positive charge density of the protein surface. The highest emulsion stability (90.22 ± 3.52%) was obtained in 0.05 m NaCl and 5% protein concentration, whereas the lowest (63.00 ± 1.06%) was in water at all protein concentrations. Protein hydrophobicity was low and depended of pH but not of NaCl. 相似文献
110.
Obead Yaseen Maher M. El‐Masri Wasim S. El Nekidy Derrick Soong Mohammed Ibrahim John W. Speirs Albert Kadri 《Hemodialysis international. International Symposium on Home Hemodialysis》2013,17(3):434-440
Hemodialysis catheter (HDC) dysfunction due to thrombosis is common, and dysfunction incidence can reach up to 50% within 1 year of use. Although administration of intraluminal alteplase (tissue plasminogen activator [tPA]) is the standard of practice to pharmacologically restore HDC function, there are no evidence‐based guidelines concerning the optimal tPA dose. The purpose of this study was to compare the efficacy of 1.0‐mg vs. 2.0‐mg tPA dwell protocols in restoring the HDC function in thrombotic dysfunctional catheters. A retrospective, single‐center study was conducted on two independent cohorts of patients; the first (n = 129) received 2.0 mg tPA/catheter lumen, while the second (n = 108) received 1.0 mg tPA/catheter lumen. Kaplan–Meier and Cox regression analyses were performed to compare the catheter survival time between patients who received 1.0 mg tPA and those who received 2.0 mg tPA. Catheter removal occurred in 25 (19.4%) of those catheters treated with 1.0 mg tPA compared with 11 (10.2%) of catheters treated with 2.0 mg tPA (P = 0.05). The hazard ratio (HR) for catheter removal was 2.75 (95% confidence interval [95%CI] = 1.25–6.04) for the 1.0‐mg tPA cohort compared with the 2.0‐mg tPA cohort. Correction added on 3 December 2012, after first online publication: The tPA cohort values were changed. Female gender (HR = 2.51; 95%CI = 1.20–5.27) and age (HR = 0.96; 95%CI = 0.94–0.98) were also associated with catheter survival. Our findings suggest that treatment of dysfunctional HDC with 2.0‐mg tPA dwells is superior to 1.0‐mg tPA dwells. 相似文献