REDUCTION OF TRICHLOROETHYLENE AS A DENSE NON-AQUEOUS PHASE BY SURFACE-MODIFIED BIMETALLIC NANOSCALE ZERO-VALENT IRON

摘要

Trichloroethylene (TCE) is one of the most important contaminants in soil and groundwater due to its highly toxic nature and long-term contamination potentials. However, it is very difficult to be removed by commercial groundwater treatment especially when it remains as dense non aqueous phase liquid (DNAPL). Thus, nanoscale zero-valent iron was introduced and it has been found as an efficient eco-material for groundwater remediation contaminated by DNAPL. In the present study, reductive dechlorination of trichloroethylene (TCE) in the form of DNAPL by bimetallic (Pd and Ni) nanoscale zero-valent iron (NZVI) was investigated in batch scale. Surface-modified bimetallic NZVI using a surfactant was also tested to study the enhanced removal of DNAPL. Bimetallic NZVI was found to have higher degradation efficiency than bare NZVI. Furthermore, surface-modification could enhance the degradation efficiency and improve the mobility and accessibility of NZVI to the DNAPL source zone as well. This is considered to be due to increased dissolution of DNAPL by lowering surface tension between water and the DNAPL phase.