Assessment of Supercritical Fluid Extraction of Pentachlorophenol from Aqueous Samples

Aranda, R; Kruus, Peeter

doi:10.1080/03067319708030480

Cited by 4 publications

(3 citation statements)

References 14 publications

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“…The dechlorination reactor consists of a column of a zero-valent bimetallic mixture of palladium and iron (Pd 0 /Fe 0 ) that is heated to 450 uC. The extraction efficiency from either the contaminated soil or the resulting aqueous surfactant suspension is influenced by the solubility of PCBs in scCO 2 , 3 the concentration of PCBs in the aqueous phase, 4,5 the operating pressure and temperature 6,7 and the solvent modifier added to the scCO 2 . [8][9][10] For optimized reaction conditions, the dechlorination is very efficient; however, the time required for efficient scrubbing is anticipated to depend on the loading of PCBs within the soil/aqueous surfactant emulsion.…”

Section: Introductionmentioning

confidence: 99%

Extractions of polychlorinated biphenyl (PCB) compounds from surfactant suspension/soil extracts with dechlorination on-line

Marshall

2001

J. Environ. Monitor.

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Polychlorinated biphenyl (PCB) formulation (Aroclor 1242 or 1248)-surfactant (Brij 97 or Triton CF54) emulsions (0.1-1.0%, v/v) were extracted with supercritical carbon dioxide (scCO2). The declinations curve that resulted for each loading of PCB substrate was accurately modelled as a single-exponential decay, and the half-life [t1/2, 10.76 min +/- 2% (Brij 97) or 10.0 min +/- 14% (Triton CF54)] was independent of the level of loading. When the extraction was combined with on-line dechlorination, t1/2 was increased to 17.62 min +/- 6% or 16.46 min +/- 5%, respectively The dechlorination reactor contributed appreciably to the back-pressure of the system so that, under identical scCO2 head pressures, the flow rate at the exit of the system was reduced from 1500 mL min-1 (as decompressed gas) to 900 mL min-1. When corrected for the difference in flow rates, the declination curves in the absence and presence of the reactor became virtually identical. For a surfactant suspension from a soil that was field-burdened with only 6 ppm PCBs, extended operation (extraction-dechlorination) for 15 h, during which the substrate suspension was replaced every 30 min, caused no loss of the dechlorination efficiency; however, for 1% (v/v) Aroclor 1242 or 1248 in surfactant suspension, the reactor gradually lost reactivity over 5 h of continued operation. However, the reactivity could be restored virtually completely by purging the reactor column with scCO2 for 3 h or washing the column at ambient temperature with 30 mL of methanol-water (7 + 3, v/v). Mass spectrometry of the reaction products indicated that the principal products included biphenyl and toluene, but methylated benzenes and phenols were also present.

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Section: Introductionmentioning

confidence: 99%

Extractions of polychlorinated biphenyl (PCB) compounds from surfactant suspension/soil extracts with dechlorination on-line

Marshall

2001

J. Environ. Monitor.

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“…1,2 The initial investigations into direct SFE of aqueous media were driven by the potential use of the technique for environmental remediation by wastewater treatment. 3,4 After the introductory tests of feasibility of the technique, [5][6][7] analytical-scale SFE of aqueous media was applied to diverse classes of analytes, e.g., polycyclic aromatic hydrocarbons, 8 pesticides, 9,10 acidic pollutants, 11 nonionic surfactants, 12 steroids, 13 pharmaceuticals, 14 and metal-ligand complexes. [15][16][17] Attention was paid to pH of the aqueous phase in a CO 2 -water system at elevated temperatures and pressures 18 and to the effect of pH on the recoveries of protic analytes from aqueous samples.…”

mentioning

confidence: 99%

“…has increasingly been complemented by SFE of aqueous samples. The direct SFE of water-based matrixes has been assisted by low mutual solubility of water and CO 2 in the relevant region of temperature and pressure. , The initial investigations into direct SFE of aqueous media were driven by the potential use of the technique for environmental remediation by wastewater treatment. , After the introductory tests of feasibility of the technique, − analytical-scale SFE of aqueous media was applied to diverse classes of analytes, e.g., polycyclic aromatic hydrocarbons, pesticides, , acidic pollutants, nonionic surfactants, steroids, pharmaceuticals, and metal−ligand complexes. − Attention was paid to pH of the aqueous phase in a CO 2 −water system at elevated temperatures and pressures and to the effect of pH on the recoveries of protic analytes from aqueous samples. It appears that the formation of carbonic acid in the aqueous phase may assist the extraction of acidic analytes and complicate the extraction of bases .…”

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confidence: 99%

Partition Coefficients of Environmentally Important Phenols in a Supercritical Carbon Dioxide−Water System from Cocurrent Extraction without Analysis of the Compressible Phase

et al. 2002

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Partition coefficients of phenol, salicylic acid, and several environmentally important chloro- and nitrophenols in a supercritical CO2-water system were measured using direct cocurrent extraction of aqueous solutions of the individual solutes with CO2. Partitioning data on the nitrophenols and salicylic acid were obtained for the first time. To bypass the troublesome and error-prone analysis of the CO2-rich phase, the present method employed only the solute concentrations in the aqueous phase before and after extraction to determine the partition coefficient. Unlike most previous engineering studies of phenol partitioning in a CO2-water system, the concentrations of phenolic solutes approached infinite dilution in both phases. This makes the results relevant to analytical-scale SFE of environmental water samples with CO2. Because of effective infinite dilution of the solutes, the partition coefficients provide a direct measure of relative CO2-philicity/hydrophilicity of the individual phenols. Compared to the octanol-water partition coefficients of substituted phenols, the CO2-water partition coefficients are more sensitive to substitution in the position neighboring the hydroxyl group.

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Analytical supercritical fluid extraction

Castro

García

2002

Techniques and Instrumentation in Analytical Chemistry

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Assessment of Supercritical Fluid Extraction of Pentachlorophenol from Aqueous Samples

Cited by 4 publications

References 14 publications

Extractions of polychlorinated biphenyl (PCB) compounds from surfactant suspension/soil extracts with dechlorination on-line

Extractions of polychlorinated biphenyl (PCB) compounds from surfactant suspension/soil extracts with dechlorination on-line

Partition Coefficients of Environmentally Important Phenols in a Supercritical Carbon Dioxide−Water System from Cocurrent Extraction without Analysis of the Compressible Phase

Analytical supercritical fluid extraction

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