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Geert-jan Witkamp - One of the best experts on this subject based on the ideXlab platform.

  • Mixed Solvent reactive recrystallization of trona sodium sesqui carbonate into soda sodium carbonate anhydrate
    Hydrometallurgy, 2007
    Co-Authors: Robert S. Gärtner, Geert-jan Witkamp
    Abstract:

    Abstract A new conversion process for the production of soda (Na2CO3(s)) from trona (Na2CO3·NaHCO3·2H2O(s)) and other sodium bicarbonate containing sodium carbonate sources is presented. By using a Mixed Solvent consisting of ethylene glycol and water, the boiling point of the solution was increased and the stability of trona could be decreased to such a degree, that it spontaneously recrystallized to anhydrous soda (Na2CO3(s)) and wegscheiderite (Na2CO3·3NaHCO3(s)). Additionally, the sodium bicarbonate content could be completely decomposed thermally in the Mixed Solvent into sodium carbonate, which crystallized as stable, pure anhydrous soda. Fundamental mechanisms of this process are discussed: The stability of trona as a function of Mixed Solvent composition, water activity and temperature is reported. The dissolution rate, the bicarbonate decomposition rate as well as the (pseudo) solid phase conversion rate of trona were investigated as functions of Mixed Solvent composition and temperature. It was found that beyond a certain temperature, depending on the Mixed Solvent composition, the trona would convert via the (pseudo) solid state.

  • Regeneration of Mixed Solvent by electrodialysis: selective removal of chloride and sulfate
    Journal of Membrane Science, 2005
    Co-Authors: Robert S. Gärtner, F.g. Wilhelm, Geert-jan Witkamp, Matthias Wessling
    Abstract:

    The applicability of electrodialysis for the selective removal of sulfate and chloride ions from a Mixed Solvent solution of sodium carbonate is investigated. The Mixed Solvent consists of 70 wt.% ethylene glycol and 30 wt.% water. Six different ion exchange membranes, the homogeneous membranes Neosepta CM-2, AM-3, AMX and ACM as well as the heterogeneous FuMA Tech CM-A and AM-A, are tested for their chemical and physical resistance to the Mixed Solvent carbonate solution, their ethylene glycol retention, their electrical resistance in the Mixed Solvent and their selectivity for sulfate and chloride over carbonate transport.

  • Regeneration of Mixed Solvent by Ion Exchange Resin: Selective Removal of Chloride and Sulfate
    Separation Science and Technology, 2005
    Co-Authors: Robert S. Gärtner, Geert-jan Witkamp
    Abstract:

    Abstract The selective extraction of sulfate and chloride ions from Mixed Solvent solutions was investigated. The Mixed Solvents consisted of water and 50 to 100%‐w (salt‐free Solvent) ethylene glycol. The extraction was measured for Mixed Solvent solutions containing only sulfate and chloride, and Mixed Solvent solutions saturated with trona (sodium sesquicarbonate, Na2CO3 · NaHCO3 · 2H2O(s). Three anion exchange resins, Dowex 1X8‐50, Dowex 21K‐Cl, and Dowex MSA‐1, were investigated for their chemical and physical resistance to the Mixed Solvent carbonate/bicarbonate solutions, for their swelling behavior in the different Mixed Solvents, and for their extraction efficiency for chloride and sulfate. The loading of the ion exchangers was fitted to a Langmuir‐type sorption model. While the extraction from trona‐free Mixed Solvents was well reproduced, the loading of the ion exchangers with chloride and sulfate from trona‐saturated Mixed Solvent solutions did not fit the sorption model. It appears, rather, t...

Ibrahim A Alsarra - One of the best experts on this subject based on the ideXlab platform.

  • thermodynamics of the solubility of reserpine in 2 2 ethoxyethoxy ethanol water Mixed Solvent systems at different temperatures
    The Journal of Chemical Thermodynamics, 2015
    Co-Authors: Faiyaz Shakeel, Nazrul Haq, Nasir A Siddiqui, Fars K Alanazi, Ibrahim A Alsarra
    Abstract:

    Abstract Thermodynamics of solubility of the bioactive compound reserpine in various {2-(2-ethoxyethoxy)ethanol + water} Mixed Solvent systems was investigated in this study. The solubility of reserpine was determined from T  = (298.15 to 338.15) K at atmospheric pressure using the reported method of Higuchi and Connors. Values of the measured solubility of reserpine were correlated with the ideal and Yalkowsky models. The root mean square deviations (RMSD) were observed to be less than 0.020 by an ideal model. However, the RMSD values were observed as less than 0.050 by the Yalkowsky model. The mole fraction solubility of reserpine was observed highest in pure 2-(2-ethoxyethoxy)ethanol (7.69 · 10 −4 at T  = 298.15 K) and lowest in pure water (9.71 · 10 −7 at T  = 298.15 K) at each temperature investigated. The results of the Van’t Hoff and Krug analysis (thermodynamic studies) indicated endothermic and spontaneous dissolution of reserpine in all {2-(2-ethoxyethoxy)ethanol + water} Mixed Solvent systems.

  • thermodynamics of solubility of isatin in peg 400 water Mixed Solvent systems at t 298 15 to 338 15 k
    The Journal of Chemical Thermodynamics, 2015
    Co-Authors: Faiyaz Shakeel, Nazrul Haq, Fars K Alanazi, Ibrahim A Alsarra
    Abstract:

    Abstract Thermodynamics of solubility of the weak water-soluble bioactive compound isatin in various {polyethylene glycol 400 (PEG 400) + water} Mixed Solvent systems were studied using Van’t Hoff and Krug analysis. The solubility of isatin was measured from T = (298.15 to 338.15) K at atmospheric pressure using the shake flask method. Values of the measured solubility were correlated with three semi-empirical models that included an ideal model, the modified Apelblat model and Yalkowsky model. The root mean square deviations were observed to be less than 4.00% by all three semi-empirical models. All three models showed a correlation coefficient of about 0.99. The mole fraction solubility of isatin was found to be highest in pure PEG 400 (9.85 · 10−2 at T = 298.15 K) and lowest in pure water (5.14 · 10−5 at T = 298.15 K) over the region studied from T = (298.15 to 338.15) K. The results of thermodynamic parameters (dissolution enthalpy, Gibbs free energy and dissolution entropy) indicated an endothermic, spontaneous and entropy driven dissolution process of isatin in all (PEG 400 + water) Mixed Solvent systems.

Robert S. Gärtner - One of the best experts on this subject based on the ideXlab platform.

  • Mixed Solvent reactive recrystallization of trona sodium sesqui carbonate into soda sodium carbonate anhydrate
    Hydrometallurgy, 2007
    Co-Authors: Robert S. Gärtner, Geert-jan Witkamp
    Abstract:

    Abstract A new conversion process for the production of soda (Na2CO3(s)) from trona (Na2CO3·NaHCO3·2H2O(s)) and other sodium bicarbonate containing sodium carbonate sources is presented. By using a Mixed Solvent consisting of ethylene glycol and water, the boiling point of the solution was increased and the stability of trona could be decreased to such a degree, that it spontaneously recrystallized to anhydrous soda (Na2CO3(s)) and wegscheiderite (Na2CO3·3NaHCO3(s)). Additionally, the sodium bicarbonate content could be completely decomposed thermally in the Mixed Solvent into sodium carbonate, which crystallized as stable, pure anhydrous soda. Fundamental mechanisms of this process are discussed: The stability of trona as a function of Mixed Solvent composition, water activity and temperature is reported. The dissolution rate, the bicarbonate decomposition rate as well as the (pseudo) solid phase conversion rate of trona were investigated as functions of Mixed Solvent composition and temperature. It was found that beyond a certain temperature, depending on the Mixed Solvent composition, the trona would convert via the (pseudo) solid state.

  • Regeneration of Mixed Solvent by electrodialysis: selective removal of chloride and sulfate
    Journal of Membrane Science, 2005
    Co-Authors: Robert S. Gärtner, F.g. Wilhelm, Geert-jan Witkamp, Matthias Wessling
    Abstract:

    The applicability of electrodialysis for the selective removal of sulfate and chloride ions from a Mixed Solvent solution of sodium carbonate is investigated. The Mixed Solvent consists of 70 wt.% ethylene glycol and 30 wt.% water. Six different ion exchange membranes, the homogeneous membranes Neosepta CM-2, AM-3, AMX and ACM as well as the heterogeneous FuMA Tech CM-A and AM-A, are tested for their chemical and physical resistance to the Mixed Solvent carbonate solution, their ethylene glycol retention, their electrical resistance in the Mixed Solvent and their selectivity for sulfate and chloride over carbonate transport.

  • Regeneration of Mixed Solvent by Ion Exchange Resin: Selective Removal of Chloride and Sulfate
    Separation Science and Technology, 2005
    Co-Authors: Robert S. Gärtner, Geert-jan Witkamp
    Abstract:

    Abstract The selective extraction of sulfate and chloride ions from Mixed Solvent solutions was investigated. The Mixed Solvents consisted of water and 50 to 100%‐w (salt‐free Solvent) ethylene glycol. The extraction was measured for Mixed Solvent solutions containing only sulfate and chloride, and Mixed Solvent solutions saturated with trona (sodium sesquicarbonate, Na2CO3 · NaHCO3 · 2H2O(s). Three anion exchange resins, Dowex 1X8‐50, Dowex 21K‐Cl, and Dowex MSA‐1, were investigated for their chemical and physical resistance to the Mixed Solvent carbonate/bicarbonate solutions, for their swelling behavior in the different Mixed Solvents, and for their extraction efficiency for chloride and sulfate. The loading of the ion exchangers was fitted to a Langmuir‐type sorption model. While the extraction from trona‐free Mixed Solvents was well reproduced, the loading of the ion exchangers with chloride and sulfate from trona‐saturated Mixed Solvent solutions did not fit the sorption model. It appears, rather, t...

Bin Chen - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Mixed Solvent on the morphologies of nanostructured Bi2S3 prepared by solvothermal synthesis
    Materials Letters, 2008
    Co-Authors: Jian Ping Zhou, Xiao-bing Bian, Jiao Li, Xiaobo Wang, Bin Chen
    Abstract:

    Abstract Different morphologies of nanostructured bismuth sulfide (Bi 2 S 3 ) including nanotubes and nanorods have been prepared by solvothermal synthesis at a low temperature of 120 °C for 12 h using various Mixed Solvents as the reaction medium and urea as the mineralizer. X-ray diffraction analysis showed that all the as-prepared Bi 2 S 3 samples are orthorhombic phase. Transmission electron microscopy analysis showed that the morphologies of the nanostructures are mainly related to the viscosity and surface tension of the Mixed Solvent used in the solvothermal synthesis.

Faiyaz Shakeel - One of the best experts on this subject based on the ideXlab platform.

  • thermodynamics of the solubility of reserpine in 2 2 ethoxyethoxy ethanol water Mixed Solvent systems at different temperatures
    The Journal of Chemical Thermodynamics, 2015
    Co-Authors: Faiyaz Shakeel, Nazrul Haq, Nasir A Siddiqui, Fars K Alanazi, Ibrahim A Alsarra
    Abstract:

    Abstract Thermodynamics of solubility of the bioactive compound reserpine in various {2-(2-ethoxyethoxy)ethanol + water} Mixed Solvent systems was investigated in this study. The solubility of reserpine was determined from T  = (298.15 to 338.15) K at atmospheric pressure using the reported method of Higuchi and Connors. Values of the measured solubility of reserpine were correlated with the ideal and Yalkowsky models. The root mean square deviations (RMSD) were observed to be less than 0.020 by an ideal model. However, the RMSD values were observed as less than 0.050 by the Yalkowsky model. The mole fraction solubility of reserpine was observed highest in pure 2-(2-ethoxyethoxy)ethanol (7.69 · 10 −4 at T  = 298.15 K) and lowest in pure water (9.71 · 10 −7 at T  = 298.15 K) at each temperature investigated. The results of the Van’t Hoff and Krug analysis (thermodynamic studies) indicated endothermic and spontaneous dissolution of reserpine in all {2-(2-ethoxyethoxy)ethanol + water} Mixed Solvent systems.

  • thermodynamics of solubility of isatin in peg 400 water Mixed Solvent systems at t 298 15 to 338 15 k
    The Journal of Chemical Thermodynamics, 2015
    Co-Authors: Faiyaz Shakeel, Nazrul Haq, Fars K Alanazi, Ibrahim A Alsarra
    Abstract:

    Abstract Thermodynamics of solubility of the weak water-soluble bioactive compound isatin in various {polyethylene glycol 400 (PEG 400) + water} Mixed Solvent systems were studied using Van’t Hoff and Krug analysis. The solubility of isatin was measured from T = (298.15 to 338.15) K at atmospheric pressure using the shake flask method. Values of the measured solubility were correlated with three semi-empirical models that included an ideal model, the modified Apelblat model and Yalkowsky model. The root mean square deviations were observed to be less than 4.00% by all three semi-empirical models. All three models showed a correlation coefficient of about 0.99. The mole fraction solubility of isatin was found to be highest in pure PEG 400 (9.85 · 10−2 at T = 298.15 K) and lowest in pure water (5.14 · 10−5 at T = 298.15 K) over the region studied from T = (298.15 to 338.15) K. The results of thermodynamic parameters (dissolution enthalpy, Gibbs free energy and dissolution entropy) indicated an endothermic, spontaneous and entropy driven dissolution process of isatin in all (PEG 400 + water) Mixed Solvent systems.