Superfund Research Program
A New Solar-Powered Approach for Groundwater Decontamination
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Trichloroethylene (TCE), a chlorinated hydrocarbon that is used as an industrial solvent and degreaser, is one of the most common soil and groundwater contaminants in the United States. A research team led by Akram Alshawabkeh, Ph.D., from the Northeastern University Superfund Research Program has developed a new, low-cost strategy for remediating this contaminant.
In a study published in the February 2012 edition of Environmental Science & Technology, the researchers outline a novel method that uses iron ions (Fe(II)) along with a palladium (Pd) catalyst to enhance oxidative degradation of TCE, which typically occurs as a side reaction during traditional TCE hydrodechlorination. Their method is particularly suited for sustained treatment of aquifers since a solar-powered system can be engineered for in situ implementation.
To develop the method, Songhu Yuan, Ph.D., a visiting professor from the China University of Geosciences in Wuhan, China, together with Xuhui Mao, Ph.D., a postdoctoral research associate at Northeastern University, applied mixed metal oxide electrodes to simulated TCE-contaminated groundwater to generate H2 in a lab-controlled environment. They added palladium powder to catalyze the reaction, which degraded TCE into ethane and other byproducts. Without the addition of Fe(II), 40% of the TCE was degraded within 80 minutes. However, when Yuan added Fe(II), 95% of the TCE was degraded within the same amount of time. He found that adding Fe(II) shifts the process of TCE decontamination from hydrodechlorination (a reduction process) to a more rapid oxidative reaction. This shift was most effective when high concentrations of iron (about 10 mg/L) were present and the pH of the water was low. This is the first time a research group has reported on palladium’s ability to indirectly catalyze an oxidation process for groundwater remediation.
The researchers believe that this may be a low-cost and highly efficient method to remediate contaminated groundwater. They used the results to devise a three-electrode Pd-catalytic remediation system with automatic pH-regulation, which they are currently evaluating. (click on image to enlarge) They are also developing an in-well solar-powered system for field testing.
For More Information Contact:
Akram N Alshawabkeh
501 Stearns Center
360 Huntington Ave.
Boston, MA 02115-5000
To learn more about this research, please refer to the following sources:
- Yuan S, Mao X, Alshawabkeh AN. 2012. Efficient degradation of TCE in groundwater using Pd and electro-generated H2 and O2: a shift in pathway from hydrodechlorination to oxidation in the presence of ferrous ions. Environ Sci Technol 46(6):3398-3405. doi:10.1021/es204546u PMID:22315993 PMCID:PMC3319670
- Mao X, Ciblak A, Amiri M, Alshawabkeh AN. 2011. Redox control for electrochemical dechlorination of trichloroethylene in bicarbonate aqueous media. Environ Sci Technol 45(15):6517-6523. doi:10.1021/es200943z PMID:21671641 PMCID:PMC3150566
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