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Papers by Marzieh Rezayat

The Journal of Supercritical Fluids, 2011

Supercritical carbon dioxide was used for partially selective extraction of triacetin from a mixt... more Supercritical carbon dioxide was used for partially selective extraction of triacetin from a mixture of triacetin, diacetin, and monoacetin with a molar ratio of 1:2:1. The extraction was carried out in two stages. In the first stage, a central composite design was used to optimize the four variables of pressure, temperature, liquid CO 2 flow rate, and extraction time at three levels using a semi-continuous, supercritical carbon dioxide extraction setup. The composition of the extract under the predicted optimum conditions (i.e., 109 bar, 56 • C, 0.86 mL min −1 , and 61 min) was about 69% triacetin accompanied by only 30% diacetin and no detectable monoacetin. In the second stage, the effect of the two factors, pressure (100, 109, and 140 bar) and liquid CO 2 flow rates of 0.86 and 1.5 mL min −1 measured at average laboratory temperature (27 • C) and pressure (0.89 bar), were studied using a continuous, supercritical carbon dioxide fractionation setup equipped with a glass-bead packed column kept under a thermal gradient of 56-70 • C. The experimental design was organized as a 3 × 2 general factorial design. Under the best conditions (i.e., 140 bar and 1.5 mL min −1), the extraction yield of triacetin and diacetin were 41.8 and 3.0%, respectively, without any detectable monoacetin as verified by GC-FID.

The Journal of Supercritical Fluids, 2010

Using a continuous flow apparatus, the ternary solubility of mono-and di-tert-butyl ethers of gly... more Using a continuous flow apparatus, the ternary solubility of mono-and di-tert-butyl ethers of glycerol (MTBG and DTBG, respectively) in supercritical carbon dioxide was measured at the temperatures of 313.15, 333.15, and 348.15 K; a pressure range of 80-200 bar; and an expanded gas flow rate of 180 ± 10 mL min −1 at average laboratory temperature of 300.15 K and pressure of 0.89 bar. The ternary solubility of the ethers at the constant temperatures of 333.15 and 348.15 K increased with increasing pressure up to the crossover point (i.e., 152 bar for MTBG and 170 bar for DTBG). MTBG exhibited a higher solubility than DTBG in scCO 2. The experimental data for the ternary solubility of MTBG and DTBG were correlated using the Bartle equation.

The Journal of Supercritical Fluids, 2010

A quantitative structure property relationship (QSPR) model was conducted for the first time pred... more A quantitative structure property relationship (QSPR) model was conducted for the first time prediction of the percent conversion of esterification reactions in supercritical carbon dioxide (scCO 2 ). The data set consisting of 42 esterification reactions of different acids and alcohols in ...

Green Chemistry, 2009

Continuous esterification of glycerol with acetic acid was investigated in supercritical carbon d... more Continuous esterification of glycerol with acetic acid was investigated in supercritical carbon dioxide (scCO 2 ) using Amberlyst 15® as a heterogeneous catalyst. The effect of pressure at (65–300) bar on the substrate conversion and the reaction yield and selectivity was ...

Fluid Phase Equilibria, 2005

The co-solubility in supercritical carbon dioxide of 1-butanol, 1-pentanol, 2-ethyl-1-hexanol, or... more The co-solubility in supercritical carbon dioxide of 1-butanol, 1-pentanol, 2-ethyl-1-hexanol, or 1-decanol in the presence of 2-ethylhexanoic acid in the pressure range of 100-180 bar and at 313 or 323 K was measured. The solubility of these alcohols in the presence of 2-ethylhexanoic acid is lower than in the systems alcohol + CO 2 and remains nearly constant in the pressure range of 120-180 bar, with the exception of 1-decanol. The lower selectivities in the ternary systems are explained by strong intermolecular hydrogen bonding between alcohol molecules and 2-ethylhexanoic acid molecules. The FT-IR spectra of mixtures of alcohols and 2-ethylhexanoic acid at a 1:1 mole ratio in the liquid CCl 4 confirmed this conclusion.

Continuous esterification of glycerol with acetic acid was investigated in scCO2 using Amberlyst ... more Continuous esterification of glycerol with acetic acid was investigated in scCO2 using Amberlyst 15 as a heterogeneous catalyst. The effect of pressure at (65-300) bars on the substrates conversion and selectivity was studied. With increasing the pressure, the percent of total conversion decreases from 82% to 61.4% and the selectivity of triacetin (TA) synthesis increased while the selectivity was decreased for mono and diacetin (DA). The effect of temperature on the conversion and the selectivity at (100-150)oC was also investigated. With increasing temperature, the selectivity of triacetin decreased while it was increased for monoacetin (MA). With increasing the mole ratio of acetic acid to glycerol to 24, selectivity of 100% was achieved while the conversion was 51.5% for the continuous triacetin synthesis in scCO2. Use of scCO2, alone as solvent with no catalyst, had the MA selectivity of 100%, with the conversion of 29.5%. Moreover, the total conversion using the high pressure ...

The Journal of Supercritical Fluids, 2017

ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesi... more ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesized in a single step from Pd(hexafluoroacetylacetonate)2 (Pd(hfac)2) in subcritical and supercritical carbon dioxide. CNXLs acted as both the reducing agent and support material for the obtained nanoparticles. Dry Pd nanoparticles supported on the cellulose nanocrystals (PdNP@CNXL) were obtained by simply venting the CO2 and were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The results show that the Pd nanoparticle diameters varied between 6 and 13 nm with varying pressure (240?2200 psi), reaction time (2?17 h), and weight ratio of the precursor Pd(hfac)2 to CNXL (1?4% w/w). Particles with diameters above 13 nm appeared not to remain attached to the CNXL surface. Reaction conditions also affected the Pd loading in the final PdNP@CNXL composite. Finally, the PdNP@CNXL composites were shown

By using a continuous flow apparatus, binary solubility of n-butanol, 2-butanol, iso and tert-but... more By using a continuous flow apparatus, binary solubility of n-butanol, 2-butanol, iso and tert-butanol in supercritical carbon dioxide (SC-CO2) have been measured at constant temperature of 323 K and at flow rate of 140±10 mL/min in the pressure range of (70 to 140) bar. Different ...

ACS Sustainable Chemistry & Engineering, 2014

ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesi... more ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesized in a single step from Pd(hexafluoroacetylacetonate)2 (Pd(hfac)2) in subcritical and supercritical carbon dioxide. CNXLs acted as both the reducing agent and support material for the obtained nanoparticles. Dry Pd nanoparticles supported on the cellulose nanocrystals (PdNP@CNXL) were obtained by simply venting the CO2 and were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The results show that the Pd nanoparticle diameters varied between 6 and 13 nm with varying pressure (240?2200 psi), reaction time (2?17 h), and weight ratio of the precursor Pd(hfac)2 to CNXL (1?4% w/w). Particles with diameters above 13 nm appeared not to remain attached to the CNXL surface. Reaction conditions also affected the Pd loading in the final PdNP@CNXL composite. Finally, the PdNP@CNXL composites were shown

Supercritical carbon dioxide (SC-CO 2) has been studied as a medium for esterification of camel h... more Supercritical carbon dioxide (SC-CO 2) has been studied as a medium for esterification of camel hump fat and tristearin in producing cocoa butter analog using Immobilized Thermomyces lanuginosus lipase (Lipozyme TL IM) as a biocatalyst. Process conditions (pressure, temperature, tristearin/camel hump fat ratio, water content, and incubation time) were optimized by conducting experiments at five different levels using the response surface method (RSM). A second-order polynomial response surface equation was developed indicating the effect of variables on cocoa butter analog yield. Contour maps generated using the response surface equation showed that all the experimental variables significantly affected the yield. The pressure, 10 MPa; temperature, 40 • C; SSS/CHF ratio, 1:1; water content, 10% (w/w); and incubation time, 3 h were found to be the optimum conditions to achieve the maximum yield of cocoa butter analog.

The Journal of Supercritical Fluids, 2011

Supercritical carbon dioxide was used for partially selective extraction of triacetin from a mixt... more Supercritical carbon dioxide was used for partially selective extraction of triacetin from a mixture of triacetin, diacetin, and monoacetin with a molar ratio of 1:2:1. The extraction was carried out in two stages. In the first stage, a central composite design was used to optimize the four variables of pressure, temperature, liquid CO 2 flow rate, and extraction time at three levels using a semi-continuous, supercritical carbon dioxide extraction setup. The composition of the extract under the predicted optimum conditions (i.e., 109 bar, 56 • C, 0.86 mL min −1 , and 61 min) was about 69% triacetin accompanied by only 30% diacetin and no detectable monoacetin. In the second stage, the effect of the two factors, pressure (100, 109, and 140 bar) and liquid CO 2 flow rates of 0.86 and 1.5 mL min −1 measured at average laboratory temperature (27 • C) and pressure (0.89 bar), were studied using a continuous, supercritical carbon dioxide fractionation setup equipped with a glass-bead packed column kept under a thermal gradient of 56-70 • C. The experimental design was organized as a 3 × 2 general factorial design. Under the best conditions (i.e., 140 bar and 1.5 mL min −1), the extraction yield of triacetin and diacetin were 41.8 and 3.0%, respectively, without any detectable monoacetin as verified by GC-FID.

The Journal of Supercritical Fluids, 2010

Using a continuous flow apparatus, the ternary solubility of mono-and di-tert-butyl ethers of gly... more Using a continuous flow apparatus, the ternary solubility of mono-and di-tert-butyl ethers of glycerol (MTBG and DTBG, respectively) in supercritical carbon dioxide was measured at the temperatures of 313.15, 333.15, and 348.15 K; a pressure range of 80-200 bar; and an expanded gas flow rate of 180 ± 10 mL min −1 at average laboratory temperature of 300.15 K and pressure of 0.89 bar. The ternary solubility of the ethers at the constant temperatures of 333.15 and 348.15 K increased with increasing pressure up to the crossover point (i.e., 152 bar for MTBG and 170 bar for DTBG). MTBG exhibited a higher solubility than DTBG in scCO 2. The experimental data for the ternary solubility of MTBG and DTBG were correlated using the Bartle equation.

The Journal of Supercritical Fluids, 2010

A quantitative structure property relationship (QSPR) model was conducted for the first time pred... more A quantitative structure property relationship (QSPR) model was conducted for the first time prediction of the percent conversion of esterification reactions in supercritical carbon dioxide (scCO 2 ). The data set consisting of 42 esterification reactions of different acids and alcohols in ...

Green Chemistry, 2009

Continuous esterification of glycerol with acetic acid was investigated in supercritical carbon d... more Continuous esterification of glycerol with acetic acid was investigated in supercritical carbon dioxide (scCO 2 ) using Amberlyst 15® as a heterogeneous catalyst. The effect of pressure at (65–300) bar on the substrate conversion and the reaction yield and selectivity was ...

Fluid Phase Equilibria, 2005

The co-solubility in supercritical carbon dioxide of 1-butanol, 1-pentanol, 2-ethyl-1-hexanol, or... more The co-solubility in supercritical carbon dioxide of 1-butanol, 1-pentanol, 2-ethyl-1-hexanol, or 1-decanol in the presence of 2-ethylhexanoic acid in the pressure range of 100-180 bar and at 313 or 323 K was measured. The solubility of these alcohols in the presence of 2-ethylhexanoic acid is lower than in the systems alcohol + CO 2 and remains nearly constant in the pressure range of 120-180 bar, with the exception of 1-decanol. The lower selectivities in the ternary systems are explained by strong intermolecular hydrogen bonding between alcohol molecules and 2-ethylhexanoic acid molecules. The FT-IR spectra of mixtures of alcohols and 2-ethylhexanoic acid at a 1:1 mole ratio in the liquid CCl 4 confirmed this conclusion.

Continuous esterification of glycerol with acetic acid was investigated in scCO2 using Amberlyst ... more Continuous esterification of glycerol with acetic acid was investigated in scCO2 using Amberlyst 15 as a heterogeneous catalyst. The effect of pressure at (65-300) bars on the substrates conversion and selectivity was studied. With increasing the pressure, the percent of total conversion decreases from 82% to 61.4% and the selectivity of triacetin (TA) synthesis increased while the selectivity was decreased for mono and diacetin (DA). The effect of temperature on the conversion and the selectivity at (100-150)oC was also investigated. With increasing temperature, the selectivity of triacetin decreased while it was increased for monoacetin (MA). With increasing the mole ratio of acetic acid to glycerol to 24, selectivity of 100% was achieved while the conversion was 51.5% for the continuous triacetin synthesis in scCO2. Use of scCO2, alone as solvent with no catalyst, had the MA selectivity of 100%, with the conversion of 29.5%. Moreover, the total conversion using the high pressure ...

The Journal of Supercritical Fluids, 2017

ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesi... more ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesized in a single step from Pd(hexafluoroacetylacetonate)2 (Pd(hfac)2) in subcritical and supercritical carbon dioxide. CNXLs acted as both the reducing agent and support material for the obtained nanoparticles. Dry Pd nanoparticles supported on the cellulose nanocrystals (PdNP@CNXL) were obtained by simply venting the CO2 and were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The results show that the Pd nanoparticle diameters varied between 6 and 13 nm with varying pressure (240?2200 psi), reaction time (2?17 h), and weight ratio of the precursor Pd(hfac)2 to CNXL (1?4% w/w). Particles with diameters above 13 nm appeared not to remain attached to the CNXL surface. Reaction conditions also affected the Pd loading in the final PdNP@CNXL composite. Finally, the PdNP@CNXL composites were shown

By using a continuous flow apparatus, binary solubility of n-butanol, 2-butanol, iso and tert-but... more By using a continuous flow apparatus, binary solubility of n-butanol, 2-butanol, iso and tert-butanol in supercritical carbon dioxide (SC-CO2) have been measured at constant temperature of 323 K and at flow rate of 140±10 mL/min in the pressure range of (70 to 140) bar. Different ...

ACS Sustainable Chemistry & Engineering, 2014

ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesi... more ABSTRACT Palladium nanoparticles (PdNPs) supported on cellulose nanocrystals (CNXL) were synthesized in a single step from Pd(hexafluoroacetylacetonate)2 (Pd(hfac)2) in subcritical and supercritical carbon dioxide. CNXLs acted as both the reducing agent and support material for the obtained nanoparticles. Dry Pd nanoparticles supported on the cellulose nanocrystals (PdNP@CNXL) were obtained by simply venting the CO2 and were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The results show that the Pd nanoparticle diameters varied between 6 and 13 nm with varying pressure (240?2200 psi), reaction time (2?17 h), and weight ratio of the precursor Pd(hfac)2 to CNXL (1?4% w/w). Particles with diameters above 13 nm appeared not to remain attached to the CNXL surface. Reaction conditions also affected the Pd loading in the final PdNP@CNXL composite. Finally, the PdNP@CNXL composites were shown

Supercritical carbon dioxide (SC-CO 2) has been studied as a medium for esterification of camel h... more Supercritical carbon dioxide (SC-CO 2) has been studied as a medium for esterification of camel hump fat and tristearin in producing cocoa butter analog using Immobilized Thermomyces lanuginosus lipase (Lipozyme TL IM) as a biocatalyst. Process conditions (pressure, temperature, tristearin/camel hump fat ratio, water content, and incubation time) were optimized by conducting experiments at five different levels using the response surface method (RSM). A second-order polynomial response surface equation was developed indicating the effect of variables on cocoa butter analog yield. Contour maps generated using the response surface equation showed that all the experimental variables significantly affected the yield. The pressure, 10 MPa; temperature, 40 • C; SSS/CHF ratio, 1:1; water content, 10% (w/w); and incubation time, 3 h were found to be the optimum conditions to achieve the maximum yield of cocoa butter analog.