G. Anitescu, L. Tavlarides
Jan 2, 2002
Citations
1
Influential Citations
25
Citations
Journal
Industrial & Engineering Chemistry Research
Abstract
Experimental results and kinetic analyses are presented for the dechlorination/oxidation of the 3,3‘,4,4‘-tetrachlorobiphenyl (T4CB) congener in supercritical water (SCW) at 25.3 MPa and 673−773 K. A plug-flow reactor is employed with nominal T4CB feed concentrations of 2.97−5.48 μmol/L in methanol solutions (1.71 mmol/L) using H2O2 as the oxidant. Conversions vary from 20.2% (5.76 s at 673 K) to 99.5% (20.7 s at 773 K). The overall conversion is independent of the concentration of O2 and follows apparent second order with Arrhenius parameters of A = 1020.7±0.1 s-1 (mol/L)-1 and Ea = 219 ± 2 kJ/mol. Methanol functions as a rate enhancer by inducing a free-radical reaction pathway of consecutive dechlorinations leading to biphenyl, which then oxidizes to mineral products. Positively identified reaction intermediate products are lower chlorinated PCB congeners (3,3‘,4- and 3,4,4‘-TriCB; 3,3‘-, 3,4-, 3,4‘-, and 4,4‘-DiCB; and 3- and 4-CB), biphenyl, CO, and CO2. Successive global reaction networks with secon...