Dechlorination of trichloroethylene (TCE) by zero-valent iron. 6

ABSTRACT Dechlorination of TCE was done using zero-valent iron in two forms: powder and shavings. A simulated TCE solution of initial concentration 5 ppm was mixed with iron powder, finer than 100 mesh, in 120-mL serum bottles. The pH of the solution was varied at 5, 7 and 9; the amount of iron powder was at 10, 12.5 and 15 mg per mL of TCE solution; and the water used was distilled de-ionized water. On the other hand, 50 grams of iron shavings were used as materials packed in a glass column passed with simulated TCE solutions. Two thicknesses of the shavings were used (1 mm and 1.5 mm). The iron shavings were subjected to different preparations: pretreated with 0.1 M NaCl solution and untreated; and the water used was de-oxygenated, de-ionized distilled water. Samples taken at different intervals were analyzed for TCE and chloride ion concentrations. Results showed a decrease in the concentration of TCE, accompanied by the formation and increase in chloride ion concentration over time, thus confirming the dechlorination of TCE. Degradation was possible when the pH of the solution was 7 and below, while better dechlorination was observed with the thinnest iron shavings possible and with the said shavings subjected to pretreatment with the NaCl solution. 56

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