Prelaboratory Questions And Problems

1. Find three examples of substances that have been treated in real situations by electrokinetic remediation.

2. Biological methods are recommended as the first choice in many soil remediation scenarios due in part to their low cost. Name at least two situations where, in general, electrochemical methods are recommended instead.

3. The production of a basic front that originates at the cathode in a soil electrokinetic remediation site produces, as a side effect, the precipitation of a metal ion front, M"+ that is attracted and travels toward the cathode. In other words, the OH~ and M"+ ions meet at a certain point in the field and an insoluble metal hydroxide, M(OH)„, precipitates as a result. (This phenomenon is similar to the analytical technique called isoelectric focusing). The end result is that the metal becomes concentrated ("focused") in a narrow band, which facilitates its removal. Assuming that the OH~ ions travel twice as fast as the monovalent metal ion, M+ draw a one-dimensional sketch simulating the remediation site (the two extremes are the two electrodes placed for remediation), and mark the point where the focusing should result.

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