Novel CO2-soluble pyridine derivatives and the extraction of heavy metals into Sc-CO2

Guo

2010

CLEAN Soil Air Water

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Three fluorinated bipyridine ligands have been designed and synthesized as chelating agents for the extraction of metal ions in supercritical CO 2 (sc-CO 2 ). The ligand solubilities in sc-CO 2 were investigated at different temperatures and pressures, and the measured data have been correlated using a semiempirical model. The calculated results showed satisfactory agreement with the experimental data. Based on these data, metal ion extraction with the three compounds as chelating agents in sc-CO 2 was performed from spiked filter paper, whereby ligand 1 showed the highest extraction efficiency, especially for Ni 2+ and Cu 2+ . The extraction constants, K ex , of the three chelating ligands were seen to increase with increasing extraction efficiency for the same metal ion in the same extraction system.

Section: Introductionmentioning

confidence: 99%

“…1 H NMR spectra were recorded on a Mercury Plus 400 MHz instrument at ambient temperature using TMS as an internal standard; 13 C and 19 F NMR spectra were recorded on a Bruker 400 MHz instrument. Elemental analysis was performed using a PE 2400 series II CHNS/O elemental analyzer.…”

Section: Introductionmentioning

confidence: 99%

Metal Ion Extraction with Bipyridine Derivatives as Chelating Ligands in Supercritical Carbon Dioxide

Guo

2010

CLEAN Soil Air Water

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“…Interestingly, a fluorinated tertiary amide-containing 8-HQ derivative (4d) created a single phase with a surprisingly low pressure compared to other 8-HQ derivatives in this study. In previous work, we have described that the solubility difference between secondary and tertiary amide analogs 20 results from two main forces, self-interaction between chelating agents (solutesolute), and specific intermolecular interaction between the chelating agent (solute) and the CO 2 molecule (solvent). 22 Strong self-interaction of solute molecules would decrease their solubility in CO 2 , but strong specific intermolecular solute-solvent (CO 2 ) interaction would enhance the CO 2 -solubility of the solute.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, we have already designed and synthesized various highly CO 2 -soluble chelating agents, which are amide-group-containing pyridine derivatives containing fluorinated or non-fluorinated alkyl chains on the amide group in the 4-position of the pyridine ring. 20,21 We observed that all of these compounds were CO 2 -soluble and therefore suitable for metal extraction investigations. In this paper, we describe the synthesis and evaluation of novel CO 2 ) into CO 2 .…”

Section: Introductionmentioning

confidence: 89%

“…The apparatus for solubility testing and metal extraction have been described in our former work. 20,21 A brief introduction is given here. A compound was charged in a variable-volume view cell equipped with two sapphire windows (V min = 10 mL, V max = 20 mL, 0.2 mL/rotation; Hanwoul Eng., Korea) by a micropipette, and the cell was sealed tightly.…”

Section: Apparatus and Materialsmentioning

confidence: 99%

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Highly CO₂-soluble 5-Amido-8-hydroxyquinoline Chelating Agents for Extraction of Metals in Sc-CO₂

Chang¹,

Park²,

Bulletin of the Korean Chemical Society

2008

Novel CO 2 -soluble 8-hydroxyquinoline (8-HQ) chelating agents were synthesized and evaluated for solubility and metal ion extraction ability in supercritical CO 2 (Sc-CO 2 ). Among them, secondary amide-containing 8-HQ derivatives cannot be dispersed well into Sc-CO 2 , but tertiary amide-containing derivatives can dissolve completely in Sc-CO 2 even at low CO 2 pressures, perhaps owing to the predominant intermolecular interaction between the chelating agent and the CO 2 molecule. Based on 8-HQ chelating agent solubility data, we investigated the extraction of metal ions (Co , and Zn 2+ ) using two highly CO 2 -soluble 8-HQ derivatives (4d, 4e) in Sc-CO 2 . The extraction efficiency of tertiary amide-containing 8-HQ ligands, both fluorinated and non-fluorinated forms, was dramatically increased in the presence of diethyl amine (organic base). We suggest that diethyl amine could play an important synergistic role in the stronger metal binding ability of 8-HQ through an in situ deprotonation reaction in Sc-CO 2 medium.

Metal Ions Extraction from Solid Matrix in Supercritical Carbon Dioxide with DMBP as Chelating Ligand

Tian

Wang

2010

CLEAN Soil Air Water

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The effects of pressure, temperature, time, and ligand to metal ratio (50:1-200 , and Pb 2þ ) were tested, respectively, to be extracted from solid matrix into sc-CO 2 . The best extraction efficiency for Co 2þ (83.68%) was obtained in the optimized condition (DMBP and perfluoro-1-octanesulfonic acid tetraethylammonium salt as a co-ligand used, 25 MPa, 323 K, 20 min, ligand to metal ratio of 200). Extraction from mixed metal ions with DMBP was also achieved and the results showed that selectivity for Co 2þ ion was notable (98.17%) in the above-mentioned conditions. Finally, the detailed calculation results exhibited that the extraction constants (K ex ) of the metal ions increased with the increase of the extraction efficiency in the same extraction system.