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M. D. Luque De Castro - One of the best experts on this subject based on the ideXlab platform.

  • Pressurised liquid-liquid extraction. An approach to the removal of inorganic non-metal species from used Industrial Oils.
    Chemosphere, 2004
    Co-Authors: S. Morales-muñoz, Jose L. Luque-garcia, M. D. Luque De Castro
    Abstract:

    Abstract Modified pressurised hot water is used for the development of a high pressure liquid–liquid extraction method for the decontamination of used Industrial Oils from inorganic non-metal species (chlorine, fluorine and sulphur). The Oils were subjected to dynamic extraction with water modified with 5% v/v HNO3 at 200 °C as extractant. Under these working conditions the analytes were transferred to the aqueous phase. Spontaneous separation of the two immiscible liquid phases (the used oil and extract) takes place in the collection flask after extraction. The treated and untreated oil samples were oxidised and the chloride, fluoride and sulphate thus formed were determined by ion-chromatography. The method was applied to four oil samples from different locations in Spain. A residence time of ≅10 min provided oil samples from which 88.3%, 89.4% and 89.4% of chloride, fluoride and sulphate, respectively, have been removed with respect to the initial concentration of each analyte in the oil. The repeatability, expressed as relative standard deviation (RSD), was of 11.9%, 13.7% and 7.2% for Cl−, F− and SO42−, respectively; whilst the within-laboratory reproducibility yielded RSDs of 6.2%, 7.9% and 6.2% for the same analytes. The proposed approach has proved to be efficient, simple, easily transferable to Industrial scale, cheap, fast and environmentally friendly.

  • OPTIMISATION AND ASSESSMENT OF A METHOD FOR DETERMINATION OF TRACE METALS IN USED Industrial Oils
    Analytical Letters, 2001
    Co-Authors: V Fernández-pérez, L. F Braña-redondo, M. D. Luque De Castro
    Abstract:

    The selection of a method for the determination of trace metals in used Industrial Oils led to the use of graphite furnace atomic absorption spectrometry (GF-AAS) as the best technique for sample decomposition/atomisation/detection. After this step, the instrumental variables were studied with special emphasis on optimising the type of diluent used as function of both the physical characteristics of the sample and the concentration of the analytes to the GF-AAS instrument. A key aspect of the method was the type of standard (organic or inorganic solutions) used for calibration which yielded very different metal concentrations for the same samples. The use of a certified reference material (NIST CRM 1084a) enabled to assess organic solutions of metal as the best for calibration. Then, the method thus validated was applied to different used Industrial Oils.

  • Continuous liquid–liquid extraction using modified subcritical water for the demetalisation of used Industrial Oils
    Analytica Chimica Acta, 2001
    Co-Authors: V Fernández-pérez, M.m Jiménez-carmona, M. D. Luque De Castro
    Abstract:

    Abstract Modified subcritical water is proposed as an extractant for the development of a liquid–liquid extraction method for the demetalisation of used Industrial Oils. The two immiscible liquid phases (the used oil and water modified with 4% (v/v) HNO 3 +0.1 M KCl) enter into contact in an approach designed by the authors, consisting of an extraction coil in stainless steel located into an electrically heated oven. After close contact between the two immiscible phases for proper mass transfer, the oil–water segments leave the oven through the restrictor, then are cooled by passage through a coil located in a bath at room temperature. Spontaneous separation of both phases takes place in the collection flask at the end of the cooling coil. The metals (Cu, V, Pb, Ni, Cd and Cr) extracted into the aqueous phase are determined by graphite furnace atomic absorption spectrometry. An in-depth study of variables affecting the demetalisation-extraction step as well as those concerning the hydrodynamic variables was performed. The method was validated using a Certified Reference Material (C.R.M. 1086a; Wear Metals in Oil, N.I.S.T., Gaithersburg, MA) and applied to five different used Industrial Oils. A residence time of 270 s provides oil samples purified to 75, 85, 95, 90, 98 and 90% (with respect to the initial concentration of each metal in the oil) for Cu, V, Pb, Cd, Cr and Ni, respectively. While the extraction time was 270 s, the complete method was achieved in about 40 min. The proposed approach proves to be cheap, quick and avoids handling the organic samples.

Boris Mizaikoff - One of the best experts on this subject based on the ideXlab platform.

  • Detecting trace amounts of water in hydrocarbon matrices with infrared fiberoptic evanescent field sensors
    The Analyst, 2011
    Co-Authors: Yuliya Luzinova, Bogdan Zdyrko, Igor Luzinov, Boris Mizaikoff
    Abstract:

    Water is a common contaminant in a variety of Industrial Oils and petroleum products. Thus, the detection of water in these products is of substantial relevance. Hence, this study focuses on quantifying trace amounts of water in hydrocarbons using hexane as a model system for Industrial Oils and petroleum matrices via mid-infrared (MIR) evanescent field absorption spectroscopy. A silver halide fiberoptic waveguide was used to interrogate in situwater-in-hexane emulsions. Either unmodified fibers or waveguides surface-modified with polyacrylic acid layers were used. The limits of detection (LOD) and limits of quantification (LOQ) of water in hexane utilizing tin-crosslinked polyacrylic acid modified fibers were 76 and 170 ppm, respectively. Consequently, the IR absorption signature of water in hexane is detectable at concentrations as low as 10 ppm. The proposed fiberoptic sensing strategy requires a single measurement only, requires no sample preparation, and thus has potential for the direct in situ detection and monitoring of water in Industrial Oils and petroleum products.

Yuliya Luzinova - One of the best experts on this subject based on the ideXlab platform.

  • Detecting trace amounts of water in hydrocarbon matrices with infrared fiberoptic evanescent field sensors
    The Analyst, 2011
    Co-Authors: Yuliya Luzinova, Bogdan Zdyrko, Igor Luzinov, Boris Mizaikoff
    Abstract:

    Water is a common contaminant in a variety of Industrial Oils and petroleum products. Thus, the detection of water in these products is of substantial relevance. Hence, this study focuses on quantifying trace amounts of water in hydrocarbons using hexane as a model system for Industrial Oils and petroleum matrices via mid-infrared (MIR) evanescent field absorption spectroscopy. A silver halide fiberoptic waveguide was used to interrogate in situwater-in-hexane emulsions. Either unmodified fibers or waveguides surface-modified with polyacrylic acid layers were used. The limits of detection (LOD) and limits of quantification (LOQ) of water in hexane utilizing tin-crosslinked polyacrylic acid modified fibers were 76 and 170 ppm, respectively. Consequently, the IR absorption signature of water in hexane is detectable at concentrations as low as 10 ppm. The proposed fiberoptic sensing strategy requires a single measurement only, requires no sample preparation, and thus has potential for the direct in situ detection and monitoring of water in Industrial Oils and petroleum products.

M Luque D De Castro - One of the best experts on this subject based on the ideXlab platform.

  • continuous liquid liquid extraction using modified subcritical water for the demetalisation of used Industrial Oils
    Analytica Chimica Acta, 2001
    Co-Authors: V Fernandezperez, M M Jimenezcarmona, M Luque D De Castro
    Abstract:

    Abstract Modified subcritical water is proposed as an extractant for the development of a liquid–liquid extraction method for the demetalisation of used Industrial Oils. The two immiscible liquid phases (the used oil and water modified with 4% (v/v) HNO 3 +0.1 M KCl) enter into contact in an approach designed by the authors, consisting of an extraction coil in stainless steel located into an electrically heated oven. After close contact between the two immiscible phases for proper mass transfer, the oil–water segments leave the oven through the restrictor, then are cooled by passage through a coil located in a bath at room temperature. Spontaneous separation of both phases takes place in the collection flask at the end of the cooling coil. The metals (Cu, V, Pb, Ni, Cd and Cr) extracted into the aqueous phase are determined by graphite furnace atomic absorption spectrometry. An in-depth study of variables affecting the demetalisation-extraction step as well as those concerning the hydrodynamic variables was performed. The method was validated using a Certified Reference Material (C.R.M. 1086a; Wear Metals in Oil, N.I.S.T., Gaithersburg, MA) and applied to five different used Industrial Oils. A residence time of 270 s provides oil samples purified to 75, 85, 95, 90, 98 and 90% (with respect to the initial concentration of each metal in the oil) for Cu, V, Pb, Cd, Cr and Ni, respectively. While the extraction time was 270 s, the complete method was achieved in about 40 min. The proposed approach proves to be cheap, quick and avoids handling the organic samples.

V Fernández-pérez - One of the best experts on this subject based on the ideXlab platform.

  • OPTIMISATION AND ASSESSMENT OF A METHOD FOR DETERMINATION OF TRACE METALS IN USED Industrial Oils
    Analytical Letters, 2001
    Co-Authors: V Fernández-pérez, L. F Braña-redondo, M. D. Luque De Castro
    Abstract:

    The selection of a method for the determination of trace metals in used Industrial Oils led to the use of graphite furnace atomic absorption spectrometry (GF-AAS) as the best technique for sample decomposition/atomisation/detection. After this step, the instrumental variables were studied with special emphasis on optimising the type of diluent used as function of both the physical characteristics of the sample and the concentration of the analytes to the GF-AAS instrument. A key aspect of the method was the type of standard (organic or inorganic solutions) used for calibration which yielded very different metal concentrations for the same samples. The use of a certified reference material (NIST CRM 1084a) enabled to assess organic solutions of metal as the best for calibration. Then, the method thus validated was applied to different used Industrial Oils.

  • Continuous liquid–liquid extraction using modified subcritical water for the demetalisation of used Industrial Oils
    Analytica Chimica Acta, 2001
    Co-Authors: V Fernández-pérez, M.m Jiménez-carmona, M. D. Luque De Castro
    Abstract:

    Abstract Modified subcritical water is proposed as an extractant for the development of a liquid–liquid extraction method for the demetalisation of used Industrial Oils. The two immiscible liquid phases (the used oil and water modified with 4% (v/v) HNO 3 +0.1 M KCl) enter into contact in an approach designed by the authors, consisting of an extraction coil in stainless steel located into an electrically heated oven. After close contact between the two immiscible phases for proper mass transfer, the oil–water segments leave the oven through the restrictor, then are cooled by passage through a coil located in a bath at room temperature. Spontaneous separation of both phases takes place in the collection flask at the end of the cooling coil. The metals (Cu, V, Pb, Ni, Cd and Cr) extracted into the aqueous phase are determined by graphite furnace atomic absorption spectrometry. An in-depth study of variables affecting the demetalisation-extraction step as well as those concerning the hydrodynamic variables was performed. The method was validated using a Certified Reference Material (C.R.M. 1086a; Wear Metals in Oil, N.I.S.T., Gaithersburg, MA) and applied to five different used Industrial Oils. A residence time of 270 s provides oil samples purified to 75, 85, 95, 90, 98 and 90% (with respect to the initial concentration of each metal in the oil) for Cu, V, Pb, Cd, Cr and Ni, respectively. While the extraction time was 270 s, the complete method was achieved in about 40 min. The proposed approach proves to be cheap, quick and avoids handling the organic samples.