I&EC 17 |
| In this work a hybrid technology combining the injection of the slurry of palladized nanoiron (PNI) and electrokinetic remediation process was used to mimic the removal and degradation of trichloroethylene (TCE) and nitrate in the subsurface environment. Laboratory-prepared palladized nanoiron was characterized to be in the range 50-80 nm with a specific surface area of 101 m2/g. PNI was further stabilized using 1 vol% polyacrylic acid as a dispersant. The nanosized Pd/Fe slurry thus prepared was then used to evaluate the treatment efficiency of combined technologies of the injection of the slurry of PNI and electrokinetic remediation process in treating TCE- or nitrate-contaminated loamy sand in horizontal columns. The initial TCE concentration in soil ranged from 160-181mg/kg, while nitrate concentration was 7316 mg/kg. Test conditions used were: (1) electric potential gradient: 1 V/cm; (2) daily addition of 20 mL of the slurry of PNI (2.5 g/L and 4.0 g/L for the cases of TCE and nitrate, respectively) to the electrode reservoir(s); and (3) reaction time: 6 days. The addition of PNI slurry to the anode reservoir yielded the lowest residual TCE concentration in soil, namely about 92.5% removal of TCE from soil. The residual TCE concentration in the cathode reservoir was about 8 mg/L. Although the addition of PNI slurry to the cathode reservoir could completely degrade TCE therein, its residual TCE in soil was up to 29.0%. In the case of nitrate decontamination, by injecting nanosized Pd/Fe slurry into the anode reservoir of the EK system, an efficiency of over 99% nitrate removal and degradation for the entire system was achieved. The cathode reservoir, however, was found to be the worst injection position. Chemical reduction of nitrate would occur mostly in the anode reservoir where nanosized Pd/Fe bimetal existed. |
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Environmental Applications of Nanoscale and Microscale Reactive Particles
1:30 PM-5:30 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 223, Oral
Division of Industrial & Engineering Chemistry |