Dechlorination of pentachlorophenol by zero valent iron and modified zero valent irons

Journal Article · Mon May 15 04:00:00 EDT 2000 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es991129f· OSTI ID:20080462

Kim, Y H; Carraway, E R

The disappearance of pentachlorophenol (PCP) from aqueous solutions in contact with zero valent metals (ZVMs) may be due to dechlorination reactions or sorption to ZVM-related surfaces. Previously reported results on PCP and zero valent iron measured only PCP loss from aqueous solutions and attributed this loss to reaction. In this study, the total amount of unreacted PCP, both that in aqueous solution and that sorbed to ZVM-related surfaces, was measured using a modified extraction method. PCP dechlorination was confirmed by following the appearance of tetrachlorophenol isomers. The results indicate that the rate of dechlorination is much slower than previously reported. In their experiments, electrolytic zero valent iron with a surface area of 0.12 m{sup 2}/g resulted in an observed first-order rate constant of 3.9 x 10{sup {minus}3} h{sup {minus}1} or a half-life of approximately 7.4 days. Normalized to surface area, the rate constant (k{sub SA}) is 3.2 x 10{sup {minus}4} L m{sup {minus}2} h{sup {minus}1}. Four amended irons prepared by coating iron with palladium (Pd/Fe), platinum (Pt/Fe), nickel (Ni/Fe), and copper (Cu/Fe) were also used and showed slower removal rates as compared to unamended iron. Slower reaction rates obtained with amended irons as compared to iron have not been previously reported. Overall, this study conclusively demonstrates PCP dechlorination by iron and several bimetallic ZVMs and indicates that it is essential to separate reaction and sorption processes.

• Research Organization: Texas A and M Univ., College Station, TX (US)
• OSTI ID: 20080462
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 10 Vol. 34; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CHLORINATED AROMATIC HYDROCARBONS
DECHLORINATION
GROUND WATER
IRON
REMEDIAL ACTION