Basicity limits for solutes in supercritical fluid chromatography with a carbon dioxide mobile phase

Fields, Steven M.; Grolimund, Karl

doi:10.1002/jhrc.1240111010

Cited by 29 publications

(14 citation statements)

References 19 publications

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“…Any amine with a pKa value >5 can react with CO 2 in the presence of water (Field and Grolimund, 1988). According to Figure S3A, the pH value of NS-NR 2 dispersion decreased gradually with the addition of diluted hydrochloric acid (0.01 mol/L).…”

Section: Co 2 Adsorption and Kinetic Studiesmentioning

confidence: 99%

CO2 Capture With Absorbents of Tertiary Amine Functionalized Nano–SiO2

et al. 2020

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To improve CO 2 adsorption performance of nanoparticle absorbents, a novel tertiary amine functionalized nano-SiO 2 (NS-NR 2 ) was synthesized based on the 3-aminopropyltrimethoxysilane (KH540) modified nano-SiO 2 (NS-NH 2 ) via methylation. The chemical structure and performances of the NS-NR 2 were characterized through a series of experiments, which revealed that NS-NR 2 can react with CO 2 in water and nanofluid with low viscosity revealed better CO 2 capture. The CO 2 capture mechanism of NS-NR 2 was studied by kinetic models. From the correlation coefficient, the pseudo second order model was found to fit well with the experiment data. The influencing factors were investigated, including temperature, dispersants, and cycling numbers. Results has shown the additional surfactant to greatly promote the CO 2 adsorption performance of NS-NR 2 because of the better dispersity of nanoparticles. This work proved that NS-NR 2 yields low viscosity, high capacity for CO 2 capture, and good regenerability in water. NS-NR 2 with high CO 2 capture will play a role in storing CO 2 to enhanced oil recovery in CO 2 flooding.

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Section: Co 2 Adsorption and Kinetic Studiesmentioning

confidence: 99%

CO2 Capture With Absorbents of Tertiary Amine Functionalized Nano–SiO2

et al. 2020

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“…In SGC, COx can be used as the mobile phase to carry out separations which are superior to using the lighter carrier gases such as helium [1,2]. Although CO2 was claimed to be reactive with strong bases [14,15], experiments have shown that strongly basic aliphatic primary amines (pKb -4) can be eluted from both open tubular and packed columns when using neat CO2 as the mobile phase (8,16). In this study, the separation of various polar compounds in SGC was investigated using different packing materials.…”

Section: Introductionmentioning

confidence: 99%

Separation of polar compounds by solvating gas chromatography with carbon dioxide mobile phase

Shen

Lee

1997

Chromatographia

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SummaryIn this study, the separation of polar compounds in solvating gas chromatography (SGC) was investigated. Capillary columns (250 gm i.d.) packed with deactivated siliceous particles, including SE-54 encapsulated silica particles, diol-bonded silica particles, and polyethylenimine (PEI) coated particles, and nonsiliceous particles of styrene-divinylbenzene were used. Polar compounds that were used as test solutes included ketones, aldehydes, esters, nitro-containing compounds, alcohols, phenols, fatty acids, and amines. It was found that capillary columns packed with SE-54 encapsulated particles were suitable for the separation of medium polar compounds, columns packed with diol bonded silica particles could be used for separation of strongly polar compounds such as fatty acids, and columns packed with PEI coated silica particles were suitable for the separation of basic compounds such as alkylamines under SGC conditions. Columns containing the polymeric particles could be used for the separation of medium polar compounds and weak bases, however, low column efficiency was observed. SGC was found to provide better separation of polar compounds than high pressure gas chromatography (HPGC). A sample of a peppermint oil was separated within 8 min under SGC conditions.

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“…Interestingly, it was found that aliphatic amines can react with CO 2 but aromatic amines with pK a values less than 5 cannot. 25 Encouraged by this fact, we intend to apply CO 2 switchable ILs ATPSs to selectively separate aliphatic and aromatic amines from aqueous solutions at room temperature and ambient pressure. For this purpose, short-chain aliphatic amines of 1 1, and those of the ILs are illustrated in Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

Selective separation of aliphatic and aromatic amines with CO2 switchable ionic liquids aqueous two-phase systems

Xiong

Wang

et al. 2013

Green Chem.

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In many practical processes, separation of aliphatic amines from aromatic amines in water is imperative to obtain the desired products. In this work, a novel strategy was proposed for selective separation of aliphatic amines from aromatic amines with CO 2 switchable ionic liquids (ILs) aqueous two-phase systems (ATPSs). It was shown that upon introduction of CO 2 into an aqueous solution containing the IL, aliphatic amine and aromatic amine at 25 °C and atmospheric pressure, an ATPS could be formed with an IL-rich top phase and an ammonium-salt-rich bottom phase. Under these circumstances, the aromatic amine was largely partitioned in the IL-rich phase, while the aliphatic amine was transformed into the ammonium salt by the reaction with CO 2 . Thus the aliphatic amine was well separated from the aromatic amine in aqueous solution. The distribution ratios of aromatic amines between the two phases were found to increase with increasing hydrophobicity of ILs and aromatic amines, pK a values of aliphatic amines and tie-line length of the systems. Moreover, aliphatic amines retained in the ammonium-salt-rich phases were regenerated by bubbling N 2 under heating, while aromatic amines in the IL-rich phases were removed by simple steam distillation. The recovery efficiency for aliphatic amines was as high as 99.0%. The regenerated ILs could then be reused in the next separation process, and no decrease in the distribution ratios of aromatic amines was observed after six cycles.

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Basicity limits for solutes in supercritical fluid chromatography with a carbon dioxide mobile phase

Cited by 29 publications

References 19 publications

CO2 Capture With Absorbents of Tertiary Amine Functionalized Nano–SiO2

CO2 Capture With Absorbents of Tertiary Amine Functionalized Nano–SiO2

Separation of polar compounds by solvating gas chromatography with carbon dioxide mobile phase

Selective separation of aliphatic and aromatic amines with CO2 switchable ionic liquids aqueous two-phase systems

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