Oxidation of Aroclor 1248 in supercritical water: A global kinetic study

Journal Article · Wed Mar 01 04:00:00 EST 2000 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie990704l· OSTI ID:20019037

Anitescu, G; Tavlarides, L L

Supercritical water oxidation of extracted contaminants is the second step of a two-stage supercritical fluid technology proposed to remediate soils and sediments contaminated with polychlorinated biphenyls (PCBs) and/or polyaromatic hydrocarbons. In connection with the second step, the supercritical water oxidation rate of Aroclor 1248 (A1248), a mixture of {approximately}76 PCB congeners, is investigated at 25.3 MPa and temperatures of 723, 748, 773, and 823 K. The reactions are conducted in an isothermal, isobaric plug-flow tubular reactor, and GC/ECD, GC/FID, GC/TCD, and GC/MS chromatographic methods are employed for product analysis. Experiments are conducted at a nominal A1248 feed concentration of 5.75 x 10{sup {minus}5} mol/L (reaction conditions) using a methanol solution of 5.245 g/L (5,245 ppm) and H{sub 2}O{sub 2} as an initial oxidant (providing {approximately}20 mol +ACU- excess of O{sub 2}). Molar global conversion of A1248 varies from 36.06% (for residence time equal to 6.29 s at 723 K) to 99.95% (54.4 s at 823 K). The overall conversion follows apparent second order, and the rate constant calculated from the data leads to Arrhenius parameters of frequency factor A = 10{sup 17.0{+-}0.1} s{sup {minus}1} (mol/L){sup {minus}1} and energy of activation E{sub a} = 186 {+-} 2 kJ/mol (44.43 {+-} 0.51 kcal/mol). The congener specific analysis indicates a buildup of intermediate congener byproducts, which also undergo oxidation decomposition. The identified reaction products are mainly biphenyl, low-chlorinated PCB congeners such as 2-chlorobiphenyl and 2,2{prime}-dichlorobiphenyl, CO, and CO{sub 2}.

• Research Organization: Syracuse Univ., NY (US)
• OSTI ID: 20019037
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 3 Vol. 39; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ACTIVATION ENERGY
CHEMICAL REACTION KINETICS
OXIDATION
POLYCHLORINATED BIPHENYLS
POLYCYCLIC AROMATIC HYDROCARBONS
REMEDIAL ACTION
SEDIMENTS
SOILS
SUPERCRITICAL GAS EXTRACTION
WASTE WATER
WATER TREATMENT