Ionic Concentration
Mostrando 25-36 de 779 artigos, teses e dissertações.
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25. HS-SPME optimization and extraction of volatile compounds from soursop (Annona muricata L.) pulp with emphasis on their characteristic impact compounds
Abstract Aroma and taste are decisive factors in the selection of any food. The aim of this study was to extract the volatile compounds present in soursop (Annona muricata L.) pulp by Solid-phase microextraction (SPME) technique using 3 different fibers (DVB/CAR/ PDMS, CAR/PDMS and PDMS/DVB). An experimental design was set up to evaluate the best extraction
Food Sci. Technol. Publicado em: 29/05/2017
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26. Immobilization of lipase on mesoporous molecular sieve MCM-48 obtained using ionic solid as a structure director and esterification reaction on solvent-free
Candida antarctica lipase B (CALB) is an enzyme able to catalyze chemical reaction, however when it is used as a free enzyme, it cannot be recovered from reaction medium. One of the alternatives is to immobilize the enzymes on a support which allows the maintenance of their catalytic activities. The purpose of this paper was to immobilize the CALB on MCM-48
Quím. Nova. Publicado em: 2017-04
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27. Purification of inulinases by changing the ionic strength of the medium and precipitation with alcohols
ABSTRACT The present study evaluated the purification of inulinase by changing the ionic strength of the medium by addition of NaCl and CaCl2 followed by precipitation with n-propyl alcohol or iso-propyl alcohol. The effects of the concentration of alcohols and the rate of addition of alcohols in the crude extract on the purification yield and purification f
An. Acad. Bras. Ciênc.. Publicado em: 2017-03
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28. INVESTIGATING THE LONG-TERM STABILITY AND KINETICS OF SUPEROXIDE ION IN DIMETHYL SULFOXIDE CONTAINING IONIC LIQUIDS AND THE APPLICATION OF THIOPHENE DESTRUCTION
Abstract The long-term stability of superoxide ion (O2•−) with four ionic liquids (ILs), namely 1-(2-methoxyethyl)-1-methylpiperidinium tris(pentafluoroethyl)trifluorophosphate [MOEMPip][TPTP], 1-(3-methoxypropyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide [MOPMPip][TFSI], N-ethyl-N,N-dimethyl-2-methoxyethylammonium bis(trifluoromethylsulfony
Braz. J. Chem. Eng.. Publicado em: 2017-01
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29. EFFECTS OF NANOPARTICLES AND SURFACTANT CHARGE GROUPS ON THE PROPERTIES OF VES GEL
Abstract Application of viscoelastic surfactant (VES) fluids in hydraulic fracturing is still in the development stage, though shear thinning behavior and water solubility are the two important characteristics behind increasing interest in their use in fracturing jobs. Effects of ionic characteristics and the concentration of different surfactants on the rhe
Braz. J. Chem. Eng.. Publicado em: 2017-01
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30. Decanoic Acid Reverse Micelle-Based Coacervates for Microextraction of Silver in Natural Waters Prior to Flame Atomic Absorption Spectrometry Determination
In the present work, a novel, simple, and efficient method for the determination of silver in natural water samples was developed. The method is based on the extraction of silver with coacervate made up of decanoic acid reverse micelles and the subsequent determination by flame atomic absorption spectrometry (FAAS). Dithizone was used as a chelating agent. T
J. Braz. Chem. Soc.. Publicado em: 2016-11
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31. ANALYSIS OF THERMAL AND AQUEOUS SUSPENSION STABILITIES OF CHITOSAN BASED NANOENCAPSULATED VITAMINS
The food nutritional content is reduced as result of vitamins degradation. In order to minimize such losses, the encapsulation technique into polymeric nanoparticles (NPs) could offer an additional protection, extending the stability. The crosslinking formed by the ionic gelation process of chitosan and tripolyphosphate (Chi-TPP) has been widely used as an e
Quím. Nova. Publicado em: 2016-11
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32. Influence of Yttrium Dopant on the Structure and Electrical Conductivity of Potassium Sodium Niobate Thin Films
KNN thin films with diverse yttrium concentration (mol % = 0, 0.1, 0.3, 0.5, 0.7 and 0.9) were fabricated using sol-gel spin coating technique. Doped KNN revealed that Y3+ was successfully doped into the ABO3 perovskite lattice without changing the phase formation of KNN. The thickness of the deposited layer of KNN produced with increasing dopant concentrati
Mat. Res.. Publicado em: 24/10/2016
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33. Thermodynamic Study on the Acid-Base Properties of Antioxidant Compound Ascorbic Acid in Different NaClO4 Aqueous Ethanol Solutions
The proton dissociation equilibria of ascorbic acid were investigated using a combination of spectrophotometric/potentiometric techniques at constant temperature 25.0 ± 0.1 °C. The study was carried out over a wide range of ionic strengths of 0.1-3.0 mol dm-3 NaClO4 in ethanol-water mixture (1:1). The Gran's method was used for glass electrode calibration
J. Braz. Chem. Soc.. Publicado em: 2016-05
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34. Evaluation of the antimicrobial activity of chitosan and its quaternized derivative on E. coli and S. aureus growth
Abstract Chitosan is largely known for its activity against a wide range of microorganisms, in which the most acceptable antimicrobial mechanism is found to include the presence of charged groups in the polymer backbone and their ionic interactions with bacteria wall constituents. This interaction suggests the occurrence of a hydrolysis of the peptidoglycans
Rev. bras. farmacogn.. Publicado em: 2016-02
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35. Magnetic Nanoparticles Coated with Ionic Liquid as a Sorbent for Solid Phase Extraction of Chromium(VI) Prior to Its Determination by Electrothermal Atomic Absorption Spectrometry
A simple, sensitive and reliable method for the separation, preconcentration and determination of ultra trace amounts of chromium species has been developed. Chromium(VI) in aqueous sample was reacted with 9-phenyl-2,3,7-trihydroxy-6-fluorone to produce a chelate at pH of 5.0 and extracted onto the magnetic nanoparticles coated with the ionic liquid 1-hexade
J. Braz. Chem. Soc.. Publicado em: 2016-01
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36. CURRENT-VOLTAGE CURVES FOR TREATING EFFLUENT CONTAINING HEDP: DETERMINATION OF THE LIMITING CURRENT
Abstract Membrane separation techniques have been explored for treating industrial effluents to allow water reuse and component recovery. In an electrodialysis system, concentration polarization causes undesirable alterations in the ionic transportation mechanism. The graphic construction of the current voltage curve is proposed for establishing the value of
Braz. J. Chem. Eng.. Publicado em: 2015-12