Enhanced Perchloroethylene Reduction in Column Systems Using Surfactant-Modified Zeolite/Zero-Valent Iron Pellets
- 9 July 2002
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 36 (16), 3597-3603
- https://doi.org/10.1021/es015816u
Abstract
Surfactant- (hexadecyltrimethylammonium, HDTMA) modified zeolite (SMZ)/zero-valent iron (ZVI) pellets having high hydraulic conductivity (9.7 cm s-1), high surface area (28.2 m2 g-1), and excellent mechanical strength were developed. Laboratory column experiments were conducted to evaluate the performance of the pellets for perchloroethylene (PCE) sorption/reduction under dynamic flow-through conditions. PCE reduction rates with the surfactant-modified pellets (SMZ/ZVI) were three times higher than the reduction rates with the unmodified pellets (zeolite/ZVI). We speculate that enhanced sorption of PCE directly onto iron surface by iron-bound HDTMA and/or an increased local PCE concentration in the vicinity of iron surface due to sorption of PCE by SMZ contributed to the enhanced PCE reduction by the SMZ/ZVI pellets. Trichloroethylene and cis-dichloroethylene production during PCE reduction increased with the surfactant-modified pellets, indicating that the surfactant modification may have favored hydrogenolysis over β-elimination. PCE reduction rate constants increased as the travel velocity increased from 0.5 to 1.9 m d-1, suggesting that the reduction of PCE in the column systems was mass transfer limited.Keywords
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