Kinetic study of the hydrodechlorination of trichloroethene in water using a platinum catalyst and hydrazine.

Column experiments were used to measure the hydrodechlorination rate of relatively high concentrations of trichloroethene (TCE) (approximately 100 mg L(-1)). Trichloroethene in water was treated with a platinum on titania (Pt-TiO2) catalyst and hydrazine. The influence of some experimental conditions (i.e., flowrate, temperature, and pH) on the catalytic conversion of TCE was studied. The pseudo-first-order rate constant of the overall hydrodechlorination of TCE was approximately 1 x 10(-3) to 1 x 10(-2) s(-1) in the temperature range of 283 to 328 K and was determined from the dependence of the TCE conversion on the contact time of the feed water with the catalyst by assuming first-order kinetics. The activation energy of the catalytic hydrodechlorination of TCE was calculated as approximately 34 kJ/mol from the temperature dependence of the rate constant. The TCE conversion increases with increasing pH, and probably correlates with the presence of un-ionized hydrazine.