Supercritical carbon dioxide extraction of metals from aqueous solutions: a review

Erkey, Can

doi:10.1016/s0896-8446(99)00047-9

Cited by 261 publications

(171 citation statements)

References 53 publications

Supporting

Mentioning

161

Contrasting

Unclassified

Order By: Relevance

“…7,8 Complexing agents added to the supercritical fluid phase can neutralize the charge on the metal ion and successfully extract a wide range of metal species from both liquid and solid matrices. 3,[7][8][9][10][11][12][13] Extraction efficiencies are often limited by poor solubility of ligands and ligand/metal complexes in sc CO 2 .…”

Section: Concentrated Solution Of Contaminantmentioning

confidence: 99%

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

McCleskey¹,

Birnbaum²

2001

View full text Add to dashboard Cite

Executive Summary:This goal of this research was to build the fundamental understanding of microemulsion formation and mobility in supercritical CO 2 necessary to develop an innovative extraction system for selectively removing metals (actinides) from contaminated surfaces. Supercritical CO 2 has many advantages both for extraction from surfaces and minimization of the environmental impact of separation activities. The CO 2 solvent is an environmentally benign, inexpensive, radiologically and oxidatively stable extraction medium. We have studied reverse microemulsions that are comprised of nano-droplets of water (< 100 nm in diameter) suspended in CO 2 by a surfactant. The nano-droplets of water suspended in CO 2 take advantage of both the high solubility of metal ions in water and the high difussivity of CO 2 to penetrate pores that might be inaccessible to bulk water to aid in the complete decontamination of complex heterogeneous surfaces. The ability to readily control solubility by changing the pressure allows for facile separation of the surfactant and bound metal from the CO 2 solvent, enabling both concentration of the waste and recycle of the carbon dioxide. This extraction scheme is particularly attractive for remediation of heterogeneous waste in which small amounts of metal contaminants are dispersed throughout a large volume of solid waste. Typically, such extractions require an amount of water or solvent proportional to the volume of solid material.With microemulsions, CO 2 is effectively used as a diluent and the amount of water need only be proportional to the amount of metal to be extracted, making it possible to decontaminate grams of waste with µL of water. The stake for new selective separations is very high, as deconstruction and decontamination activities tend to produce large amounts of solid TRU waste. The disposal of TRU waste can exceed thousands of dollars/barrel, resulting in millions

show abstract

Section: Concentrated Solution Of Contaminantmentioning

confidence: 99%

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

McCleskey¹,

Birnbaum²

2001

View full text Add to dashboard Cite

show abstract

“…Carbon dioxide (CO 2 ) is extensively used in SFE technology because of its nontoxicity, low cost, superior mass transfer properties, easy recyclability, and moderate critical constants (T C = 31.1 ºC, P C = 73.8 bar). 2 Extraction of organic compounds in Sc-CO 2 has already been confirmed to be successful in industry. 3 However, because of the low solubility of metal ions and conventional metal chelating agents, direct extraction of metals into Sc-CO 2 is still highly inefficient.…”

Section: Introductionmentioning

confidence: 97%

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

Chang¹,

Park²,

Kim

2008

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

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.

show abstract

“…Environmental applications, such as the extraction of heavy metals or radionuclides from contaminated soil or metal removal from industrial waste water, have been a major focus in recent years [1], [2]. The solubility of metal-organic compounds in supercritical fluids (SF) has been the matter of several publications and reviews [3], [4][5][6]. Systematic studies of the effect that the ligand has on the solubility of these compounds in SC-CO2 have been published for metal-diketonates [7,8] and metal dithiocarbamates [9,10].…”

Section: Introductionmentioning

confidence: 99%

The Evaluation of the Dithizone Performance as a Complexing Reagent for Supercritical Co2 Extraction of Heavy Metals From Aqueous Solutions

Halili¹,

Mele²,

Arbneshi³

et al. 2016

RAD Conference Proceedings

View full text Add to dashboard Cite

Abstract. Heavy metal ions in liquid samples, apart from classical methods of extraction, can also be efficiently and environmentally friendly extracted by the use of supercritical CO2, containing a suitable complexing agent -ligand. This study represents the experimental data for the extraction of three heavy metals (Cu, Zn and Cd) from aqueous samples in the presence of dithizone as a ligand. The extractions by supercritical CO2 were accomplished at p=120 bars with t=50°C through the use of the dynamic technique. After the CO2 addition to the aqueous solution containing corresponding heavy metal ions, the pressure and temperature were set and extraction was performed in three different time periods: 30, 60 and 120 min (t=const., p=const. with a CO2 flow rate of 2 mL min −1 ). Once the extraction was stopped, the CO2 was released slowly through a restrictor. Methanol was used as a modifier (v/v) 10% and the pH value was set to 10. After the accomplishment of the extraction process, the leftover aqueous solution in the extractor was analyzed for its metal content by the use of the Atomic Absorption Spectrophotometer (AAS). The overall performance of the use of the dithizone as a ligand in all three cases of heavy metal ions enhanced greatly the extraction efficiency of these ligand/metal species.

show abstract

Supercritical carbon dioxide extraction of metals from aqueous solutions: a review

Cited by 261 publications

References 53 publications

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

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

The Evaluation of the Dithizone Performance as a Complexing Reagent for Supercritical Co2 Extraction of Heavy Metals From Aqueous Solutions

Contact Info

Product

Resources

About

Supercritical carbon dioxide extraction of metals from aqueous solutions: a review

Cited by 261 publications

References 53 publications

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

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

The Evaluation of the Dithizone Performance as a Complexing Reagent for Supercritical Co2 Extraction of Heavy Metals From Aqueous Solutions

Contact Info

Product

Resources

About

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