title: Enhanced perchloroethylene reduction in column systems using surfactant-modified zeolite/zero-valent iron pellets.
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 beta-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.
authors.affiliation: Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro 87801, USA. pzhang@uwf.edu
authors.forename: Pengfei
authors.initials: P
authors.lastname: Zhang
authors.forename: Xian
authors.initials: X
authors.lastname: Tao
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Li
authors.forename: Robert S
authors.initials: RS
authors.lastname: Bowman
mesh_terms: D000327:Adsorption; D007501:Iron / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry; D013750:Tetrachloroethylene / Q000737:chemistry*; D017641:Zeolites / Q000737:chemistry
chemical_list: D012997:Solvents; D013501:Surface-Active Agents; D017641:Zeolites; D007501:Iron; D013750:Tetrachloroethylene