Results 1 - 10 of 5786
Results 1 - 10 of 5786. Search took: 0.033 seconds
|Sort by: date | relevance|
[en] Silver nanopowders were prepared from silver 2-ethylhexylcarbamate (Ag-EHCB) complexes by simple thermal reduction at 85 .deg. C without any reducing agent in organic solvent. 2-Ethylhexylammonium 2-ethylhexylcarbamate (EHAEHC) was investigated in terms of their abilities to stabilize the silver nanoparticles (Ag-NPs) and its subsequent effects on the preventing aggregation between Ag-NPs. Conditions (concentration of stabilizer and reaction time) used to reduce Ag-EHCB complex were systematically varied to determine their effects on the sizes of Ag-NPs. The formation of the stabilized Ag-NPs were easily monitored by UV-vis spectroscopy and characterized by TGA, TEM, SEM and XRD. When EHAEHC was used as a stabilizer, Ag-NPs of 10-30 nm in diameter were easily obtained in high yield. Silver patterns were obtained from a silver nano-paste by heat treatment at 200 .deg. C in air and were found to have resistivity values of 2.9 Χ 10.8 Ω·m
[en] Complete text of publication follows. In this work, the reaction of selected dinitro-derivatives of phenol (2,6-DNP; 2,5-DNP; 2,4-DNP; 3,4-DNP) with 2-[2-(4-metoxy-phenylamino)-vinyl]-1,3,3-trimethyl-3H-indolium chloride (R) was investigated. Based on our study, a new extractive-spectrophotometric method for determination of 2,6-DNP was suggested. The acid-base properties of R were investigated previously (V. Andruch et al., Acta Chim. Slov. 54 (2007) 551-557.). The reaction appears from acidic properties of nitrophenols and basic properties of R which give assumption for formation of ion associate extracted to the appropriate organic solvent. The reaction condition, such as acidity medium, concentration of reagent, nature of organic solvent, as well as the reaction mechanism were investigated. The method showed good linearity for determination of 2,6-DNP in the present of other dinitrophenols, which was tested for analysis of real water samples spiked by DNP. This work has been supported by the Scientific Grant Agency of the Ministry of Education of the Slovak Republic and the Slovak Academy of Sciences (Grant No. 1/4451/07) and internal grant systems of Faculty of Science of P.J. Safarik University in Kosice (VVGS Grant No. 24/2009/CH). J.S. would like to say a special thanks to the International Visegrad Fund for providing a 10-month Scholarship.
[en] Highlights: ► We measure density and dynamic viscosity of pure ethylene glycol. ► We measure ternary densities with water and ethanol. ► We measure ternary dynamic viscosities with water and ethanol. ► The Eyring–Patel–Teja model correlate well ternary viscosities. ► We predict ternary dynamic viscosities with the ASOG-VISCO model. - Abstract: Ethylene glycol is an organic solvent used in extractive distillation to separate water–ethanol mixtures. An appropriate process description requires accurate physical property data. In this paper, experimental liquid densities and dynamic viscosities of pure ethylene glycol as well as the ternary system water–ethanol–ethylene glycol are presented over a wide temperature range (298.15 K to 328.15 K) at atmospheric pressure. A quadratic mixing rule was used to correlate the ternary liquid densities. The Eyring–Patel–Teja model with two Margules-type mixing rules for polar and aqueous systems is used to correlate the dynamic viscosity data over the measured ternary compositions and temperatures. An excellent agreement with experimental data is obtained. Additionally, the predictive ASOG-VISCO model demonstrated a good representation of the experimental data.
[en] Heavy organic phases have been observed on some occasions during TBP extraction process. These products, described as red oils, were considered as the main cause for process failures, specially in evaporators and concentrators. In view of safety aspects it is necessary to control organic concentration in product and waste solutions. The proposed method involves the organic removal by chloroform as a first step, followed by purification onto a silica gel column. The results are given from analysing TBP and its degradation product (DBP) by gas chromatography. (author)
[pt]Nos processos de separacao de actinideos por extracao com TBP diluente observam-se, as vezes, fases organicas pesadas, conhecidas como ''red oils''. Estes ocasionam disturbios nas fases finais de concentracao ou de disposicao. Desta forma, e necessario que se conheca o teor de organicos nessas solucoes. O metodo proposto envolve uma primeira fase de separacao dos organicos com cloroformio, purificacao por retencao em coluna de silica e, finalmente, analise do TBP e seu produto de degradacao (DBP) por cromatografia a gas. (autor)
[en] The extracting agent comprises an organophosphonic acid or phosphinic acid but instead of paraffinic hydrocarbons as diluent halogenated hydrocarbons or carboxylic acid are claimed to improve reextraction of rare earths from the organic phase
[fr]L'agent d'extraction utilise comprend un acide organophosphonique ou phosphinique mais au lieu d'utiliser comme diluant un hydrocarbure paraffinique, on a trouve que le rendement etait ameliore par l'emploi d'hydrocarbures halogenes ou d'acide carboxylique
[en] A new method has been developed that allows measurement of the concentration of solutes with polar groups in the bulk of suitable organic solvent phases as well as at the interface of this phase with an aqueous phase. The measuring method is based on the production of alpha particles and gamma rays by means of (n,α) and (n,γ) reactions in the liquid phase, in which boron or lithium compounds are solved. The alpha particles and gamma rays are detected by means of liquid scintillation. The separation of the pulses is carried out by means of pulse-shape analysis. This method can also be applied to the estimation of the interfacial area of liquid-liquid systems, since the intensity of the light emission of the scintillation solution is proportioned to the interfacial area