Non-aqueous phases

Fig. 1 illustrates possible setups that have been used in various studies. Scheme (a) allows the simulation of two equivalent interfaces between aqueous and non-aqueous phases. Scheme (b) simulates two equivalent aqueous/non-aqueous and two equivalent non-aqueous/vacuum interfaces and can be used to avoid the interactions between the aqueous phase and its images. Scheme (c), usually used when the non-aqueous phase is solid, simulates simultaneously an aqueous/non-aqueous, a solid/vacuum and an aqueous/gas interface. In addition, a confining wall at large distances from the aqueous/gas interface may be employed to prevent the loss of molecules from the simulation cell. 

FIG. 1 Geometries for simulations of aqueous/non-aqueous interfaces. A, N, G, V, and W denote aqueous phase, non-aqueous phase, gas phase, vacuum, and confining wall, respectively. The basic simulation box is indicated by thick dashes. 

Other examples of concentrated laundry liquids have been described in the literature [53]. These might be called nonaqueous or low-water formulations. They may contain nonionic and anionic surfactants, inorganic builders, enzyme and bleach additives, and an organic solvent such as a low mole AE [54]. Surfactant levels may range from 30% up to 80%. In some cases, the builder salts are dispersed as solid particles in the non-aqueous phase [55]. 

Villaume, J.F., Investigations at sites contaminated with dense non-aqueous phase liquids (DNAPLs),... 

A major breakthrough in separation of products from catalyst, in particular heat sensitive products, came with the discovery of the NAPS or Non-Aqueous Phase Separation technology. NAPS provides the opportunity to separate less volatile and/or thermally labile products. It is amenable to the separation of both polar [14] and non-polar [15] products, and it offers the opportunity to use a very much wider array of ligands and separation solvents than prior-art phase separation processes. The phase distribution characteristics of the ligand can be tuned for the process. Two immiscible solvents are... 

In normal emulsion polymerization the diffusion of monomers from droplets allows particles to grow. The polymerization is usually initiated in the aqueous phase and the oligomeric radicals either enter micelles or merge with other growing species. In the crosslinking ECP of EUP the ratio EUP/comonomer and the solubility or insolubility of both components and the initiator in the aqueous and non-aqueous phases respectively are parameters which decide whether diffusion of the reactants in the aqueous phase plays a role and where the initiation takes place. 

Emulsion copolymerization of EUP and comonomers may be initiated in the aqueous (persulfate) or in the non-aqueous phase (AIBN). On the decomposition of persulfates, sulfate and hydroxyl groups are introduced into macromolecules and microgels, thus influencing their surface properties [118,123-125]. By using AIBN as initiator a change of the chemical character of the surface and of the properties of the microgels is avoided. 

Compared with persulfates, the solubility of AIBN in water is very low (Fig. 24). At the usual reaction temperature of the ECP (70 °C) only about 2 mg of this initiator dissolves in 11 of water. This means that, irrespective of the distribution ratio in both phases, most of the AIBN in the usually applied concentration range (about 1-6 g/1) is dissolved in the non-aqueous phase. Conse-... 

Testa, S. M., 1990, Light Non-Aqueous Phase Liquid Hydrocarbon Occurrence and Remediation Strategy, Los Angeles Coastal Plain, California In Proceedings of the International Association of Hydrogeologists, Canadian National Chapter, on Subsurface Contamination by Immiscible Fluids, April, in press. 

Maguire, T. F., 1988 Transport of a Non-Aqueous Phase Liquid within a Combined Perched and Water Table Aquifer System In Proceedings of the National Water Well Association of Ground Water Scientists and Engineers FOCUS Conference on Eastern Regional Ground Water Issues, September, 1988. 

Villume, J. G. 1985, Investigations at Sites Contaminated with Dense Non-Aqueous Phase Liquids (NAPLs) Ground Water Monitoring Review, Spring, Vol. 5, No. 2, pp. 60-74. 

Huntley, D., Hawk, R. N., and Corley, H. P., 1992, Non-Aqueous Phase Hydrocarbon Saturations and Mobility in a Fine-Grained, Poorly Consolidated Sandstone In Proceedings of the 1992 Petroleum Hydrocarbons and Organic Chemicals in Groundwater Prevention, Detection, and Restoration, National Ground Water Association, Columbus, OH, pp. 223-237. 

Conner, J. A., Newell, C. J., and Wilson, D. K., 1989, Assessment, Field Testing and Conceptual Design for Managing Dense Non-Aqueous Phase Liquids (DNAPL) at a Superfund Site In Proceedings of the National Water Well Association and American Petroleum Institute Conference on Petroleum Hydrocarbons and Organic Chemicals in Groundwater Prevention, Detection, and Restoration, November, pp. 519-533. 

Ha is the more and HB is the less complexed host enantiomer in the aqueous phase. In the second type of experiment excess of racemic valine and optically pure (S)-[269] were distributed between two immiscible phases. In this experiment a 1 1 complex is formed in the non-aqueous phase in which L-valine dominates by an amount of 12.5% (CRFchc1j 1.28 and EDC 1.50). In terms of differences in free energy between the two diastereoisomeric complexes this means a difference in A(AG°) of 0.23 kcal mol-1 in favour of the (l)-S-[269] complex. Similar experiments have been carried out with crown ethers [270]—[280]. 

It assumes that there are no significant solute-solute interactions and no strong solute-solvent interactions which would influence the distribution process. Concentrations are expressed as mass/unit volume, and usually C1 refers to an aqueous phase and C2 to a non-aqueous phase. The equilibrium constant (P or K) defining this system is referred to as the partition coefficient or distribution ratio. The thermodynamic partition coefficient (P ) is given by the ratio of the respective mole fractions as follows ... 

At Lawrence Livermore National Laboratory site 300, these compounds along with trichloroethylene (TCE) were used in heat-exchanger pipes at their materials testing facility [421-423]. Subsurface contamination by these compounds resulted from leaking heat-exchanger pipes. TBOS and TKEBS were present as light non-aqueous phase liquids whereas TCE was present as a dense... 

Another analytically useful phenomenon in electrolysis at ITIES is ion transfer faciUtated by ionophores present in the non-aqueous phase [8]. If the ionophore is present at a low concentration in the non-aqueous phase and the aqueous phase contains a large concentration of the cation that is bound in a complex with the ionophore (for example as a component of the base electrolyte), then a voltammetric wave controlled by diffusion of the ionophore toward the ITIES or by diffusion of the complex formed away from the ITIES into the bulk of the organic phase appears at a potential lower than the potential of simple cation transfer. The peak height of this wave is proportional to the ionophore concentration in the solution and can be used for the determination (fig. 9.8). This effect has been observed with valinomycin, nonactin, cycUc polyethers and other substances [2,3,23]. The half-wave potential of these waves is... 

Weber WJ, Mukherji S, Peters CA, (1998) Aqueous dissolution of constituents of composite non-aqueous phase liquid contaminants. In Rubin H, Nakis N, Carberry J (eds) Soil and aquifer pollution. Springer, Heidelberg pp 123-135... 

The single largest use of ammonia is its direct apphcation as fertdizer, and in the manufacture of ammonium fertilizers that have increased world food production dramatically. Such ammonia-based fertilizers are now the primary source of nitrogen in farm soils. Ammonia also is used in the manufacture of nitric acid, synthetic fibers, plastics, explosives and miscellaneous ammonium salts. Liquid ammonia is used as a solvent for many inorganic reactions in non-aqueous phase. Other apphcations include synthesis of amines and imines as a fluid for supercritical fluid extraction and chromatography and as a reference standard in i N-NMR. 

To establish the conditions of uniform ionic concentration throughout the oil, the ionic concentration of the reversible ion in the oil must be independent of the concentration of the ion in the aqueous phases. Partial realisation of this state of affairs has been obtained by Beutner (loc. cit.) utilising salicylaldehyde as non-aqueous phase. The aldehyde contains small quantities of acid which reacts with the potassium chloride... 

Evidently the non-aqueous phase may possess acidic or basic characters either in virtue of its own properties, e.g. nitrobenzene and aniline, or through the addition of small quantities of soluble acidic or basic substances, e.g. salicylic acid to salicylaldehyde or methylamine to nitrobenzene. 

Foams are being investigated as a technology for site remediation applications. Foams may be used to treat non-aqueous-phase liquids in the soil subsurface. Foams could be used to deliver gases, surfactants, chemicals, nutrients, and bacteria to the subsurface. 

The Ferox process offers several potential advantages over conventional permeable barrier walls. For example, Ferox injection parameters may be modified to reflect the contaminant concentration heterogeneities present at most dense non-aqueous-phase liquid (DNAPL) sites. Unlike permeable walls, Ferox is not limited to the treatment of dissolved-phase contaminants and may be applied under structures. In addition, Ferox is not limited by depth and does not require the use of excessive quantities of iron powder. 

Bioslurping is a commercially available, in situ technology that combines vacuum-enhanced free-product recovery with bioventing of subsurface soils to simultaneously remediate petroleum-hydrocarbon-contaminated groundwater and soils. Vacuum-enhanced recovery utilizes negative pressure to create a partial vacuum that extracts free product and water from the subsurface. Bioventing is forced aeration to accelerate in situ bioremediation of hydrocarbons and non-aqueous-phase liquids (NAPLs). 

Biosurfactants are commercially available compounds for the in sim or ex situ treatment of hydrocarbons and non-aqueous-phase hquids (NAPLs) in soil and groundwater. Surfactants are highly surface-active compounds that solubilize and/or mobilize contaminants in the subsurface. 

In situ chemical oxidation using potassium permanganate was also demonstrated to treat dense, non-aqueous-phase liquid (DNAPL) at the Canadian Forces Base Borden in Ontario, Canada, between 1996 and 1997. This application used a series of six injection and five oxidant recovery weUs. The total cost of the project was approximately 45,000 (D18766A, p.l3). 

Waterflood oil recovery is a commercially available, in situ techuology for the treatment of groundwater contaminated with dense non-aqueous-phase liquids (DNAPLs) such as oil. Water-flood oil recovery is tailored to specific site conditions and is generally used in conjunction with barrier technologies. All information is from the vendor and has not been independently verified. 

Cosolvent flushing is an in situ technology that enhances the remediation of contaminated soils and groundwater by injecting water and a cosolvent such as alcohol (e.g., ethanol, methanol, and isopropyl) into a contaminated area. Research has shown that an organic cosolvent can also accelerate the movement of metals through a soil matrix. The alcohol causes both an increase in aqueous contaminant solubility and lowering of non-aqueous-phase liquid (NAPL)-water interfacial tension. 

SPSH has several advantages. It is applicable to sites where contaminants are present as non-aqueous-phase liquids (NAPLs). The technology reduces volatile organic carbon (VOC) removal time to a few weeks for a typical site, whereas soil vapor extraction (SVE) alone requires years for remediation. This reduction in removal time can signrhcantly decrease costs over SVE (from 2 to 10 times). Excavation and ex situ soil treatment is typically much more expensive to implement than SPSH, especially at deep sites. 

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