Suspensions, surfactants

For removal of insoluble and/or water-immiscible inorganics by emulsification with detergent solutions For removal of ester and amide-based organics and inorganic salts by chemical hydrolysis with alkaline solutions For removal of metal ions from solutions and surfaces by chelation or complexation reactions For wetting and dispersion of soils with surfactants, suspension of soil residues in order to prevent resedimentation and recontamination on metal surface For removal of surface contaminations, rust scale, mill scale, and other bound moieties (including surface layers of metal itself) by chemical dissolution with acids or alkaline deoxidation with or without the application of an electric current... 

If an oil-soluble monomer is dispersed in a continuous aqueous phase without the use of surfactants, suspension polymerization results. The viscosity of the resulting suspension will remain essentially constant over the course of the polymerization. Oil-soluble free radical initiators are used to effect polymerization. The monomer is dispersed into beads by the action of an agitator. Since little or no surfactant is used, no emulsification takes place, and, if the agitation is stopped, the monomer will form a separate bulk phase, usually above the aqueous phase. The monomer is polymerized by the initiator within the droplets, forming polymer beads of approximately the same size as the monomer droplets (0.1-10 mm diameter). The product can be readily separated from the aqueous phase (via filtration or decantation) in the form of macroscopic particles or beads, which can be easily packaged and/or transported. Heat transfer is facihtated by the presence of the continuous aqueous phase. Blocking agents such as clays or talcs are used to prevent particle ag-... 

Uses Coupling agent, adhesion promoter, antioxidant, antistat, antifoam, accelerator, blowing agent activator, catalyst, curative, corrosion inhibitor, disp. aid, emulsifier, flame retardant, foamer, hardener, impact modifier, process aid retarder, stabilizer, surfactant, suspension aid, thixotrope, wetting agent Trade Names Ken-React NZ 69... 

An alternative oxidation process is based on the electrooxidation of barium peroxide in aqueous surfactant suspensions [78] which produces the reactive intermediate barium superoxide. The system reaction has been applied to the oxidation of several halogenated organics, e.g. 1,2,4 trichlorobenzene, hexafluorobenzene, etc. Destruction is initiated by nucleophilic substitution of the halide by the superoxide ion, the resulting product is either chemically or electrochemically oxidised. The superoxide ion is stabilised by the barium ion and the surfactant. 

The different conditions for the formation of polycations are the reason for varying the synthesis procedures of lead oxide surfactant and iron oxide surfactant. The synthesis of the lead oxide surfactant compound was carried out as foUows An aqueous solution of Pb(N03)2 was adjusted to pH 7-8. This solution was combined with a suspension containing the sodium salt of hexadecylsulfonic acid in H2O and stirred for 30 min. The mixture was heated at 90°C for 3 days. The obtained product was filtered, washed with water and air-dried. The synthesis procedure for the iron oxide surfactant differed A freshly prepared solution of FeCl2 with a pH of 3 was added to a surfactant suspension of sodium hexadecylsulfonic acid. At this point the pH was adjusted to 6 by addition of aqueous NH3. After standing for 2 days at room temperature, the brown yellow product was filtered, washed with water and air-dried. The synthesis had to be carri out at room tempoature to prevent precipitation of amorphous material. 

Common features of the different polymerizations in dispersed media considered in this chapter are that the polymerization mostly proceeds through free radicals and the dispersed phase is stabilized by means of surface-active compounds (surfactants, suspension agents). The way in which the monomer dispersion is stabilized in the continuous medium largely defines the differences among these processes. Figure 4.1 summarizes the different options (with the exception of dispersion polymerization, discussed later). 

Fig. 20 Rheological experiment in Na-montmorillonite suspension with (o) HDPCl and ( ) HDTABr surfactant (suspension concentration 7.5 g/100 cm )...

One important aspect that needs to be considered at the time of evaluating a surfactant solution is the ratio of surfactant concentration to the CMC. As shown in Figures 9.3 and 9.4, the biosurfactant concentration in batch fermenters can reach values of 1-10 g/1. Furthermore, the previous discussions regarding the CMC of the different biosurfactants typically range between 15 and 150 mg/1 therefore it is possible to obtain surfactant suspensions between 7 and 700 CMCs. Many properties of surfactant solutions are a function of the CMC e.g. foaming, detergency and wetting tend to improve drastically as the surfactant concentration increases from below CMC to the CMC value, but then remain almost constant after the CMC. Therefore, solutions with low surfactant concentration, but still above their CMC, can be effective in various applications. 

Crodasinic LS30 NP Crodasinic LS95 NP Liquid Absorption Base A surfactant, suspension cones. MAKON DA-4 MAKON DA-6 ... 

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