Electrokinetics facilitating agents

ELECTROKINETIC REMOVAL OF PAHs USING FACILITATING AGENTS... 

TABLE 9.1. Examples of Electrokinetic Tests Using Facilitating Agents... 

Cyclodextrin-Enhanced EK A modified cyclodextrin termed hydropropyl j8-cyclodextrin (HPCD) may be an appropriate facilitating agent for electrokinetic... 

Facilitating agents change solution properties, such as dielectric constant, pH, and viscosity, and influence electroosmotic flow velocity, thereby impacting on PAH removal efficiency. The effect of electrokinetic variables on PAH removal has therefore been investigated to optimize operating conditions. pH adjustment and periodic voltage applications positively affect PAH removal efficiency. 

Cyclodextrins have been used for the removal of COC from soils by electrokinetics alone or in combination with other remediation techniques [12, 14, 15, 26]. In general, cyclodextrins are facilitating agents that improve the removal of COC from soil compared to other experiments with unenhanced electrokinetics, but results from cyclodextrin tests are usually less effective than tests with surfactants, iron nanoparticles, or with chemical oxidants. 

The profound effect of water on tree growth that is so widely reported may be expected with the electrokinetic model on the basis of three principal effects. Water filling the crazes as they develop will help prevent their collapse. Water, as a good solvent for ionic species, will be an excellent medium to facilitate entry of surface-active agents, which, by a process similar to that of environmental stress cracking, will advance the void and craze formation caused by the electric field. Water, with its high relative permittivity, will distort and locally enhance electric fields in the neighbourhood of the voids and crazes where it accumulates. Whether one or other of these effects dominate in a particular situation depends on the exact nature of the specimen and its environment. 

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