This project was to conduct a pilot-scale field test using well-dispersed iron nanoparticles synthesized in the laboratory. Evaluation of the field test results was mainly based on the properties of the injected iron nanoparticles (i.e., size distribution, surface charge), geochemical parameters (i.e., pH, ORP, EC and DO), and influenced radius. Surfactant solution (CSF-I) was used to disperse iron nanoparticles. CSF-I can effectively reduce the size from 66 to 20 nm and provide negative charge to the surface of iron nanopartices. The zeta potential of -1.39 mv was favorable to the transportation of ion nanoparticles in the soil and groundwater environment. The projected site, whose groundwater was mainly contaminated with PCE and TCE, is located in the northern part of Taiwan. The prepared nanoiron was separately injected by gravity into the groundwater. The dispersed iron nanoparticles showed an obvious effect of transport in the groundwater that had a significant change of ORP and DO drop down to zero, suggesting an occurrence of the dechlorination reaction. Concentrations of targeted compounds (PCE and TCE) were reduced by at least 95%, which mostly was expected to be through the reaction path of β-elimination (>70%). A very small amount of cis-1,2-DCE (<8 ppb) was detected during the test, suggesting a different reaction path (i.e., hydrogenolysis) would take place simultaneously. Moreover, no vinyl chloride (VC) was detected.

Iron nanoparticles, size distribution, geochemical parameters, DNAPLs, chlorinated volatile organic carbons, and in situ remediation