In this study, nanoscale zero-valent iron (NZVI) particles were synthesized and utilized to integrate with surfactant and electrokinetics for the remediation of perchloroethylene (PCE). The average particle diameter and specific surface area of the lab-synthesized iron particles were 109.3 nm and 129.7 m 2 g -1 , respectively. Experiments were performed in a glass sandbox to simulate the transport and degradation of PCE in the aquifer. The results of the transport tests revealed that the PCE concentrations at the bottom layer was higher than those at the mid and upper layers, and that the surfactant Tween 80 showed its conspicuous mobilization for PCE in the aquifer. As the results of the degradation tests showed, NZVI activity could be promoted by electrokinetics that enhanced the remediation performance of PCE contaminated groundwater by the NZVI reactive barrier. Chlorinated byproducts were not detected during the degradation tests, that is, PCE was completely dechlorinated by NZVI in the reactive barrier. The information collected from this study will be useful for further application of the NZVI reactive barrier system to remediate the aquifers contaminated by the chlorinated solvents.
A B S T R A C TChlorinated solvents such as tetrachloroethylene (PCE) in aquifers should be remediated due to their toxicity that limited the use of groundwater resources. Nanoscale zero-valent iron (NZVI) and palladized/iron (Pd/Fe) bimetallic particles were synthesized and employed to react with PCE in water to investigate its degradation behaviors. Batch tests were conducted in a 1 L serum bottle under airtight and anaerobic conditions with parameters of Pd mass contents, temperature, pH, and dispersant. The results showed that specific reaction rate constants (k SA ) of 5 mg L À1 PCE degraded by metal particles at 30˚C in the absence of dispersant enhanced with higher Pd mass contents on the Pd/Fe particles. Degradation rates of PCE increased as the reaction temperature was raised from 20 to 40˚C. Carboxymethyl cellulose (CMC), a dispersant, enhanced the k SA values of NZVI and 1:100 Pd/Fe particles by a factor of about 33 and 4 at 30˚C, respectively. The tests of pH control with buffer solution indicated that PCE degradation rates were promoted under acid and neutral conditions. Additionally, no chlorinated by-products were observed during the experimental period in each test. This study shows that effective dechlorination of PCE in water could be achieved by synthesized Pd/Fe and NZVI particles coupled with CMC dispersant.
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