Tsung-Yueh Tsai1, Tetsuji Okuda1, Satoshi Nakai2, Yuan-Yao Li3, Wataru Nishijima1, and Mitsumasa Okada2. (1) Environmental Research and Management Center, Hiroshima University, 1-5-3 Kagamiyama, Higashi-Hiroshima, Hiroshima, Japan, (2) Department of Material Science and Chemical System, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, Japan, (3) Department of Chemical Engineering, National Chung Cheng University, 168, University Rd., Min-Hsiung, Chia-Yi, Taiwan
The objectives of this study are to hydrodechlorinate chlorinated ethylenes using nano-carbon and activated carbon supported noble metal catalysts in methanol solvents at 20 ± 0.5 °C and atmospheric pressure and to evaluate the competitive degradation of chlorinated ethylenes. PCE was catalytically hydrodechlorinated with 5 % Pd/C at 20 ± 0.5 °C and atmospheric pressure without accumulation of TTCE and other chlorinated intermediates. Methanol was the best solvent for the degradation of PCE. NaOH addition clearly increased in degradation rate of PCE. The first order degradation rate constants for PCE, TCE and cis-1,2-DCE were 0.18, 0.64 and 2.1 min-1, respectively. These values were extremely larger than previous data and organic compounds with less chloride showed larger degradation rate. The degradation rate of PCE significantly decreased by the co-existence of TCE or cis-1,2-DCE. On the other hand, the co-existence of PCE gave little influence on the degradation of TCE and cis-1,2-DCE. These were due to competitive adsorption of chlorinated compounds on active sites on catalyst. The adsorption capacity of Pd/C catalyst for PCE significantly decreased by the co-existence of TCE or cis-1,2-DCE, whereas those of TCE and cis-1,2-DCE were independent from the co-existence of PCE.