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Dive into the research topics where Teófilo A. Graber is active.

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Featured researches published by Teófilo A. Graber.


Journal of Chromatography B: Biomedical Sciences and Applications | 2000

Model for the partition of metal ions in aqueous two-phase systems

Teófilo A. Graber; Barbara A. Andrews; Juan A. Asenjo

A model for the partition of metal ions in aqueous two-phase systems (ATPS) has been developed. The partition coefficient of a metal ion D(M), is a function of several variables of the ion (size, charge and electronegativity), characteristics of the ATPS such as type of salt, salt concentration and PEG concentration and additional inorganic salt present in the ATPS. The model has been tested for complex anions of BiX4- (BiCl4-, BiBr4- and BiI4-) and cations from groups I and II (Na+, Cs+, Ca2+, Sr2+ and Ba2+) giving a good correlation in both systems. It was found that for these systems partition coefficient increases with ion size and the variables Y which is a characteristic of the ATPS and Z which is a characteristic of the additional salt present in the system. The partition coefficient of BiX4- increases with the variable X which is a characteristic of the electrical interactions of the metal ion. The cations from groups II and I exhibit the opposite behavior, which is attributable to the ion charge.


Journal of Chromatography B: Biomedical Sciences and Applications | 2000

Drowning-out crystallisation of sodium sulphate using aqueous two-phase systems.

María E. Taboada; Teófilo A. Graber; Juan A. Asenjo; Barbara A. Andrews

A novel method to obtain crystals of pure, anhydrous salt, using aqueous two-phase systems was studied. A concentrated salt solution is mixed with polyethylene glycol (PEG), upon which three phases are formed: salt crystals, a PEG-rich liquid and a salt-rich liquid. After removal of the solid salt, a two-phase system is obtained. Both liquid phases are recycled, allowing the design of a continuous process, which could be exploited industrially. The phase diagram of the system water-Na2SO4-PEG 3350 at 28 degrees C was used. Several process alternatives are proposed and their economic potential is discussed. The process steps needed to produce sodium sulphate crystals include mixing, crystallisation, settling and, optionally, evaporation of water. The yield of sodium sulphate increases dramatically if an evaporation step is used.


Journal of The Chilean Chemical Society | 2010

SYNTHESIS AND THERMAL PROPERTIES OF TWO NEW DICATIONIC IONIC LIQUIDS

Martha Claros; Teófilo A. Graber; Iván Brito; Joselyn Albanez; José A. Gavín

abStract Two new dicationic ionic liquids 1,7-bis(3-methylimidazolium-1-yl)heptane bromide (I) and 1,8-bis(3-methylimidazolium-1-yl)octane bromide (II) have been synthesized and characterized by elemental analysis, FT-IR, 1 H and 13 C NMR, and TG-DSC techniques. The compound (I) is liquid at room temperature, whereas (II) is liquid at 42.7oC. Keywords : Dicationic Ionic liquids, thermal properties, synthesis. introduction Ionic liquids (ILs) have been recognized as potential new green alternatives to conventional organic solvents in a wide range of synthetic, catalytic, separation and electrochemical applications. They are characterized by their unique physicochemical properties, including low melting points, low inflammability, and tunable hydrophobicities. They are stable in a wide range of temperature, and have great chemical and electrochemical stability. In addition, they have negligible vapor pressures so there is no loss of solvent through evaporation, avoiding environmental problems due to volatilization


Journal of Chemical & Engineering Data | 2003

Compositions, Densities, and Refractive Indices of Potassium Chloride + Ethanol + Water and Sodium Chloride + Ethanol + Water Solutions at (298.15 and 313.15) K

Héctor R. Galleguillos; and María E. Taboada; Teófilo A. Graber; Silvia Bolado


Journal of Chemical & Engineering Data | 2001

Influence of Molecular Weight of the Polymer on the Liquid−Liquid Equilibrium of the Poly(ethylene glycol) + NaNO3+ H2O System at 298.15 K

Teófilo A. Graber; María E. Taboada; and Juan A. Asenjo; Barbara A. Andrews


Fluid Phase Equilibria | 2010

Modeling of high-pressure vapor-liquid equilibrium in ionic liquids + gas systems using the PRSV equation of state

Pedro F. Arce; P. Adrián Robles; Teófilo A. Graber; Martín Aznar


Journal of Chemical & Engineering Data | 2001

Liquid−Liquid and Solid−Liquid Equilibria of the Poly(ethylene glycol) + Sodium Sulfate + Water System at 298.15 K

María E. Taboada; and Orlando A. Rocha; Teófilo A. Graber; Barbara A. Andrews


Journal of Chemical & Engineering Data | 2004

Density, Refractive Index, Viscosity, and Electrical Conductivity in the Na2CO3 + Poly(ethylene glycol) + H2O System from (293.15 to 308.15) K

Teófilo A. Graber; Héctor R. Galleguillos; and Carol Céspedes; María E. Taboada


Journal of Chemical & Engineering Data | 2005

Compositions, Densities, Conductivities, and Refractive Indices of Potassium Chloride or/and Sodium Chloride + PEG 4000 + Water at 298.15 and Liquid-Liquid Equilibrium of Potassium Chloride or Sodium Chloride + PEG 4000 + Water at 333.15 K

María E. Taboada; and Héctor R. Galleguillos; Teófilo A. Graber; Silvia Bolado


Journal of Chemical & Engineering Data | 2002

Refractive Index, Density, and Viscosity in the NaNO3 + H2O + Poly(ethylene glycol) System at Various Temperatures

Teófilo A. Graber; Héctor R. Galleguillos; Juan A. Asenjo; Barbara A. Andrews

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Pía Hernández

University of Antofagasta

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Elsa K. Flores

University of Antofagasta

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Jaime W. Morales

Pontifical Catholic University of Valparaíso

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Iván Brito

University of Antofagasta

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Jorge A. Lovera

University of Antofagasta

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