Wetting nonaqueous

Surfactants. Surfactants (qv) perform a variety of functions in a drilling fluid. Depending on the type of fluid, a surfactant may be added to emulsify oil in water (o/w) or water in a nonaqueous Hquid (w/o), to water-wet mud soHds or to maintain the soHds in a nonwater-wet state, to defoam muds, or to act as a foaming agent. 

Solids present in oil and synthetic muds must be kept wet with the nonaqueous phase to prevent coagulation and settling and mud instabiUty. Oil-wetting agents are normally incorporated in the basic mud package. These materials are typically amines or quaternary ammonium salts having hydrocarbon chains of 10 or more carbon atoms. They also render clays or lignites oil-wet for use in viscosity and filtration control (128). 

The use of a water-immiscible Hquid to separate coal from impurities is based on the principle that the coal surface is hydrophobic and preferentially wetted by the nonaqueous medium whereas the minerals, being hydrophilic, remain suspended in water. Hence, separation of two phases produces a clean coal containing a small amount of a nonaqueous Hquid, eg, oil, and an aqueous suspension of the refuse. This process is generally referred to as selective agglomeration. 

An excellent review of experimental techniques for measuring electrical resistivity in aqueous solutions is available [34], Separators used in nonaqueous systems can be characterized by wetting them with a surfactant and measuring the electrical resistivity in an aqueous solution. Then the resistivity in a nonaqueous membrane can be estimated from Eq. (2). 

The aqueous batteries use water based electrolytes (e.g., KOH electrolyte for NiCd and NiMH and H2-SO4 electrolyte for lead acid), which are less resistive then nonaqueous electrolytes. Polyolefin materials are generally suitable for use in the manufacture of separators for these batteries, but they are not inherently wettable by aqueous electrolytes. Such electrolytes are therefore unable to penetrate the pores of a separator formed from such a material, so that ion migration through the pores in solution will not occur without modification. This problem is sometimes overcome by treating the polyolefin material with a surfactant, which allows an aqueous electrolyte to wet the material. However, such surfactant can be removed from the surfaces of the polyolefin material when electrolyte is lost from the device, for example during charging and discharging cycles, and it is not subsequently replaced on the material when the electrolyte is replenished. 

The Bjorksten organization was given a contract by the U.S. Air Force about 1949 (AFTR 6220) to explore the effect of glass fabric treatments on polyester laminate wet strength properties. A total of 2000 compounds were screened. The best of these, and still good by today s standards, was a nonaqueous solvent treatment (BJY) based on an equimolar adduct of vinyl trichlorosilane and /3-chloroallyl alcohol [3]. 

Silicone surfactants are specialty surfactants that are primarily used in applications that demand their unique properties. Most applications are based on some combination of their (a) low surface tension, (b) surface activity in nonaqueous media, (c) wetting or spreading, (d) low friction or tactile properties, (e) ability to deliver silicone in a water-soluble (or dispersible) form, (f) polymeric nature or (g) low toxicity. The major applications will be discussed briefly in following sections. 

Lessons learned from paints and inks in achieving complete wetting of powders and separation of particles to micron levels with dispersion stability to forestall settling and caking are quite applicable to aqueous and nonaque-ous flowables. 

The ammines of cobalt(II) are much less stable than those of cobalt(III) thermal decomposition of [Co(NH3)6]Cl2 is characterized by reversible loss of ammonia, whereas that of [Co(NH3)6]Cl3 is not. In his classic dichotomy of complexes, Biltz regarded [Co (NH 3)3] Cl 2 as the prototype of the normal complex and [Co(NH3)6]Cl3 as that of the Werner or penetration complex. Hexaamminecobalt-(II) chloride has been prepared by the action of gaseous ammonia on anhydrous cobalt (II) chloride or by displacing water from cobalt(II) chloride 6-hydrate with gaseous ammonia. It may also be synthesized in nonaqueous solvents by passing dry ammonia through solutions of cobalt(II) chloride in ethanol, acetone, or methyl acetate. Syntheses in the presence of water include heating cobalt(II) chloride 6-hydrate in a sealed tube with aqueous ammonia and alcohol and the treatment of aqueous cobalt(II) chloride with aqueous ammonia followed by precipitation of the product with ethanol. The latter method is used in this synthesis. Inasmuch as the compound is readily oxidized by air, especially when wet, the synthesis should be performed in an inert atmosphere. 

Figure 11 Heterogenous solid compartments in soils and sediments. NAPL signifies nonaqueous phase hquid and SOM represents soil organic matter. A—absorption into amorphous organic matter or NAPL, B—absorption into soot or black carbon, C—adsorption onto water-wet organic surfaces, D—adsorption to non-porous mineral surfaces, and E—adsorption into microvoids or microporous minerals (reproduced by permission of American Chemical Society...

Condensers These systems are generally only feasible for recovering solvents from nonaqueous wetted products. 

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