نتایج جستجو برای: solvent ratio
تعداد نتایج: 553282 فیلتر نتایج به سال:
The solvent diffusion coefficient D in a solvent-polymer system can be much larger than the ratio a/ , where a is one monomer length (about 0.5 nm) and is the dominant relaxation time measured e.g. by broadband dielectric spectroscopy [1,2]. The discrepancy can be by up to 6 orders of magnitude and more. We propose here that the solvent diffusion is dominated by path in the liquid with fast rel...
Gravitational Field-Flow Fractionation Devices Fabricated via a Hot Embossing/Thermal Bonding Method
A novel hot embossing/low temperature ethanol solvent bonding method for the fabrication of polymethylmethacrylate (PMMA) field flow fractionation devices has been developed. The separation channel on a PMMA substrate was generated by a hot embossing process without vacuum. Special temperature-pressure profiles were used to analyze the influence of the hot embossing parameters. After the hot em...
Pressurized fluid extraction (PFE) was examined as an alternative technology for the extraction of carotenoids in the green algae Haematococcus pluvialis and Dunaliella salina and kavalactones in Piper methysticum. The extraction process was optimized by varying the key extraction factors of solvent, sample-solvent ratio, temperature, and time. The selectivity and efficiency of extraction param...
For many years, commercial-grade hexane has been the preferred solvent for extracting oil from cottonseed. Recent environmental and health concerns about hexane may limit the use of this solvent; therefore, the need for a replacement solvent has become an important issue. Heptane is similar to hexane, but does not have the environmental and health concerns associated with the latter. On a labor...
The aim of this study was to develop an efficient enzymatic glycerolysis system together with physical fractionation operation for the production of monoacylglycerols (MAG) containing polyunsaturated fatty acids (PUFA), especially, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from tuna oil. The enzymatic glycerolysis system at 40-70 °C is unfortunately a multiple-phase system, whi...
A facile cellulose solvent 1,3-diallyl-2-ethylimidazolium acetate ([AAeim][OAc]) with high electrical conductivity has been designed and synthesized for the first time, via a quaternization reaction and ion exchange method. The dissolution characteristics of cellulose in this solvent were studied in detail. Meanwhile, the co-solvent system was designed by adding an aprotic polar solvent dimethy...
Fuel-cell catalyst layers (CLs) are porous electrodes that fabricated from CL inks: colloidal dispersions of particles and ion-conducting polymer (ionomer), dispersed in solvent(s). The complex interactions between the ink components ultimately dictate microstructure electrochemical performance. To control formation process optimize fuel-cell performance, knowledge these is vital. In this revie...
The one pot reaction of glyoxal and hydroxylamine hydrochloride in aqueous sodium hydroxide was found to be a safe and inexpensive method for the preparation of diaminoglyoxime. By increasing stoichiometric ratio of the hydroxylamine hydrochloride and decreasing the solvent volume, the product yield increased considerably (~ 70%).
The complexation of zinc (II) with dopamine has been investigated by spectrophotometric measurements in mixed solvent system at an ionic strength of 0.2 mol*dm-3 sodium chloride, employed (25± 0.1° C) at pH ranges of ~6 to ~7 with a high ratio of ligand to metal.
An important aspect of extraction using an organic solvent that is often ignored in many laboratory scale studies is thorough solvent recovery. Although most of the solvent can be recovered with a centrifuge, the solvent left on the ‘dry’ stream must be evaporated. A custom built pilot-scale settling tank was used to separate maize particles from ethanol extracts into water with little dilution...
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