Simultaneous mobilization of macro- and trace elements (MTEs) and polycyclic aromatic hydrocarbon (PAH) compounds from soil with a nonionic surfactant and [S,S]-ethylenediaminedisuccinic acid (EDDS) in admixture: PAH compounds.

A laboratory study was conducted to assess the feasibility of a washing process with nonionic surfactant in combination with EDDS for the simultaneous mobilization of MTEs and PAH compounds from a field-contaminated soil. Unit processes consisting of complexometric extraction and surfactant-assisted mobilization were combined with reagent regeneration and detoxification steps to generate innocuous products. Thirty minutes of ultrasonic mixing of the soil with a combination of 20 mL L(-1) surfactant suspension and a sparing quantity (2 mmol) of EDDS mobilized virtually all of the benzo[α] pyrene (B(a)P) and chrysene (Cry) and an appreciable portion of the burdens of Cd, Cr, Mn, Ni, Pb and Zn, lesser amounts of the As and Cu, but only small quantities of Al and Fe.

Simultaneous mobilization of trace elements and polycyclic aromatic hydrocarbon (PAH) compounds from soil with a nonionic surfactant and [S,S]-EDDS in admixture: metals.

This study evaluated the efficacy of soil washing with a nonionic surfactant (Brij98) in combination with a complexing reagent (ethylenediaminedisuccinic acid, [S,S]-EDDS) for the simultaneous mobilization of macro- and trace elements (MTEs) and PAH compounds from a field-contaminated soil. Soil fractionation studies indicated that an appreciable fraction of the Al, Ca, Cu, Fe and Mn was associated with the residual fraction but that much of the other trace elements (As, Cd, Cr, Ni, Pb and Zn) might be susceptible to soil washing. Ultrasonically aided mixing of the field contaminated soil with Brij98 and a sparing quantity (2 mmol) of [S,S]-EDDS, simultaneously mobilized virtually all of the benzo[α]pyrene {B(a)P} and chrysene (CRY) and appreciable quantities of the trace elements (Cd, Cr, Mn, Ni, Pb, Zn) burdens.

Scaling up a treatment to simultaneously remove persistent organic pollutants and heavy metals from contaminated soils.

Soil washing is a treatment process that can be used to remediate both organic and inorganic pollutants from contaminated soils, sludges, and sediments. A soil washing procedure was evaluated utilizing about 100g samples of soil that had been field-contaminated with arsenic, chromium, copper, pentachlorophenol (PCP), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The highest level of mobilization/detoxification was achieved in three soil washes with a mixture of 0.

Influence of various organic molecules on the reduction of hexavalent chromium mediated by zero-valent iron.

Hexavalent chromium is a priority pollutant in many countries. Reduction of Cr(VI) to Cr(III) is desirable as the latter specie is an essential nutrient for maintaining normal physiological function and also has a low mobility and bioavailability. A variety of naturally-occurring organic molecules (containing alpha-hydroxyl carbonyl, alpha-hydroxyl carboxylate, alpha-carbonyl carboxylate, phenolate, carboxylates and/or thiol groups, siderophore, ascorbic acid); chelating agents (ethylenediaminetetraacetic acid derivates, acetyacetone) and others were examined their reducing activity towards a surfactant preparation (Tween 20) containing Cr(VI) and Fe(0) under a variety of reaction conditions.

Reduction of hexavalent chromium mediated by micro- and nano-sized mixed metallic particles.

A variety of micron-scale mixed metallic particles (Pd/Fe, Ag/Fe, Cu/Fe, Zn/Fe, Co/Fe, Mg/Fe, Ni/Fe, Al/Fe, Si/Fe, Pd/Cu and Pd/Zn; and Pd/Cu/Fe, Pd/Zn/Fe and Zn/Cu/Fe) and selected nano-sized bimetallic analogs (Pd/Fe, Cu/Fe and Pd/Cu) were evaluated for reducting activity with Cr(VI) in a surfactant preparation (Tween 20) under a variety of reaction conditions. Relative to the reactivity of the zero-valent iron, the tested bimetallic mixtures (Pd/Fe>Pd/Zn>Ag/Fe>Ni/Fe>Zn/Fe>Pd/Cu>Cu/Fe) appreciably increased the pseudo-first-order rate constant. The Zn/Cu/Fe represented a cost-effective preparation providing comparable or improved kinetic parameters relative to the more expensive palladized bimetallic mixtures.

Reduction of hexavalent chromium mediated by micron- and nano-scale zero-valent metallic particles.

A variety of zero-valent metals (Al(0), Cu(0), Fe(0), Mg(0), Ni(0), Si(0) and Zn(0)), and Cu(0) and Fe(0) nano-sized particles were evaluated for reactivity towards the reduction of Cr(VI) in a surfactant preparation (Tween 20) under a selection of reaction conditions. At circum neutral pHs, a rapid inactivation of the surface was observed for almost all of the tested metals and complete reduction of Cr(VI) was achieved at acidic pH only by using Cu(0), Fe(0), Mg(0) or Zn(0). A considerable increase in reactivity (up to 100-fold) was observed for reductive remediation with nano-sized particles.

Catalytic hydrogenation of polyaromatic hydrocarbon (PAH) compounds in supercritical carbon dioxide over supported palladium.

A series of supported palladium catalysts were evaluated for their ability to mediate the complete hydrogenation of polycyclic aromatic hydrocarbon (PAH) compounds. Benzo[a]pyrene (B[a]P) or phenanthrene (Phe) in hexane was merged with a hydrogen-carbon dioxide [5% (w/w) H(2)/CO(2)] stream and transferred to a flow through mini-reactor (capacity ca. 1 g) that was maintained at 90 degrees C under a back-pressure of 20.

Continuous catalytic hydrogenation of polyaromatic hydrocarbon compounds in hydrogen-supercritical carbon dioxide.

A continuous hydrogenation device was evaluated for the detoxification of selected tri-, tetra-, or pentacyclic polyaromatic hydrocarbon (PAH) compounds {anthracene, phenanthrene, chrysene, and benzo[a]pyrene (B[a]P)} by hydrogenation. A substrate stream in hexane, 0.05-1.

Simultaneous mobilization of heavy metals and polychlorinated biphenyl (PCB) compounds from soil with cyclodextrin and EDTA in admixture.

This study evaluated the efficacy of a washing process with cyclodextrin in combination with ethylenediaminetetraacetate (EDTA) for the simultaneous mobilization of heavy metals and PCBs from a field contaminated soil. Ultrasonically aided mixing of the field contaminated soil with a combination of cyclodextrin solution (10%, w/v) and a sparing quantity (2 mmol) of EDTA, simultaneously mobilized appreciable quantities of PCBs and much of the analyte metal (Cd, Cr, Cu, Mn, Ni, Pb, Zn) burdens. Relative to the action of individual reagents, a combination of randomly methylated (RAMEB) or hydroxypropyl beta-cyclodextrin (HPCD) with EDTA did not alter the PCB extraction efficiency nor did the presence of cyclodextrin change the efficiency of mobilization of most heavy metals (Al, Cd, Cr, Fe, Mn, Ni, and Zn) but did increase the recovery of Cu and Pb modestly.

A washing procedure to mobilize mixed contaminants from soil: I. Polychlorinated biphenyl compounds.

We conducted a laboratory study to assess the feasibility of a washing process with nonionic and anionic surfactants in combination with ethylenediaminetetraacetate (EDTA) for the simultaneous mobilization of heavy metals and polychlorinated biphenyls (PCBs) from a field-contaminated soil. Unit processes consisting of complexometric extraction and surfactant-assisted mobilization were combined with reagent regeneration and detoxification steps to generate innocuous products. Ten minutes of ultrasonic mixing of the soil with a combination of 30 mL L(-1) surfactant suspension and a sparing quantity (2 mmol) of EDTA mobilized appreciable quantities of PCBs, virtually all of the available Cd, Cu, Mn, and Pb, and lesser amounts of the Zn, Ni, and Cr but only small quantities of Al and Fe.

A washing procedure to mobilize mixed contaminants from soil: II. Heavy metals.

We conducted a laboratory study to assess the efficiency of nonionic and anionic surfactants in combination with a sparing quantity of ethylenediaminetetraacetate (EDTA) to simultaneously extract heavy metals (HMs) and polychlorinated biphenyl (PCB) compounds from a field-contaminated soil. A soil wash that mobilized both HMs and PCBs was combined with back-extraction with hexane to remove PCBs from the aqueous wash. The aqueous washing suspension was then regenerated by precipitation of the HMs induced by corrosion and hydrolysis of zero-valent Mg to provide a cleaned soil and innocuous extract.

Catalytic hydrogenation of polycyclic aromatic hydrocarbons over palladium/gamma-Al2O3 under mild conditions.

As a prelude to the optimization of a continuous decontamination system, catalytic hydrogenations of selected tri-, tetra- and penta-cyclic aromatic hydrocarbon compounds over commercial alumina supported palladium were investigated under mild conditions ( approximately 90 degrees C/0.42 MPa H2) and interpreted in the light of reports from the literature. Acenaphthylene, acenaphthene, anthracene, phenanthrene, chrysene and benzo[alpha]pyrene were hydrogenated, virtually completely, to saturated polycyclic hydrocarbon compounds with no appreciable evidence of carbon-carbon bond rearrangement during equilibration.

Effect of surfactant alkyl chain length on soil cadmium desorption using surfactant/ligand systems.

The effect of surfactant alkyl chain length on soil Cd desorption was studied using nonionic surfactants of polyethylene oxide (PEO) of PEO chain lengths of 7.5 (Triton X-114), 9.5 (Triton X-100), 30 (Triton X-305), or 40 units (Triton X-405) in combination with the I- ligand.

Simultaneous soil Cd and PCB decontamination using a surfactant/ligand solution.

The simultaneous desorption of Cd and PCBs, from a contaminated soil, was investigated using a surfactant/ligand solution. The test surfactants were combinations of a nonionic surfactant [polyethylene oxide (PEO) of chain length 7.5 (Triton X-114), 9.

Characterization of DNA adducts from lung tissue of asphalt fume-exposed mice by nanoflow liquid chromatography quadrupole time-of-flight mass spectrometry.

A bioanalytical method based on nanoflow liquid chromatography coupled to a hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry was developed to characterize selected polyaromatic hydrocarbon (PAH)-DNA adducts. The collision-induced dissociation of analytes results in characteristic fragmentation patterns that can be utilized to identify the DNA adducts. In the experiment, 32 B6C3F1 mice were exposed daily (4h/day) to asphalt fume in a whole-body inhalation chamber for 10 days; 16 nonexposed mice served as controls.

Dechlorination of pentachlorophenol in supercritical carbon dioxide with zero-valent palladium-magnesium bimetallic mixture.

A stream of substrate pentachlorophenol [PCP, 5 mg min(-1) in water-methanol (1 + 4, v/v)] was merged with 1.5 ml min(-1) of supercritical carbon dioxide (scCO2) and delivered to a reactor column (25 cm x 1 cm) of zero-valent palladium-magnesium mixture. The resulting dechlorinations, although very efficient, were not quantitative.

Recycling of complexometric extractants to remediate a soil contaminated with heavy metals.

Equilibrations were performed with complexing reagent(s) to mobilise Cd, Cu, Mn, Ni, Pb and Zn from a contaminated urban soil. The metal-laden aqueous extract was treated with zero-valent magnesium (Mg0) or bimetallic mixture (Pd0/Mg0 or Ag0/Mg0) to precipitate the heavy metals from solution while liberating the chelating reagent(s). Post precipitation, the pH of aqueous supernatant fraction was readjusted to approximately 5 and the solution was re-combined with the soil particulates to extract more heavy metal pollutants.