Dechlorination of Chlorinated Organic Compounds by Chemically Modified Zero Valent Iron (ZVI) Nanoparticles

Dechlorination of chlorinated organic compounds (TCE and 1,1,1-TCA) was investigated with chemically modified zero valent iron (ZVI) nanoparticles. Chemical modification of ZVI nanoparticles was carried out using Pd as catalyst and CMC (carboxymethyl cellulose) as stabilizer. The chemical modification of ZVI using Pd was found to form bimetallic nanoparticles (FePd). Additionally, CMC was used to enhance stability of FePd nanoparticles, which leads to increase in dispersivity of FePd nanoparticls. The average of TCE removal efficiency by FePd nanoparticles was significantly increased by ~ 85% compared to employing conventional ZVI nanoparticles (~15%). This increase in TCE removal efficiency is likely due to the increase in the amount of atomic hydrogen produced by formation of FePd nanoparticles. TEM images showed that CMC prevents FePd nanopartilces from aggregation, resulting in improvement of dispersivity of FePd nanoparticles. However, there is no significant improvement of TCE removal efficiency when FePd nanoparticles are stabilized using CMC compared to employing non-stabilized FePd nanoparticles. For 1,1,1-TCA, the average of 1,1,1-TCA removal efficiency by CMC-stabilized FePd nanoparticles (FePd+CMC) was ~56%. This result suggests that structure of chemicals influence their degradation rate. When pseudo first order model was applied to describe the dechlorination of TCE and 1,1,1-TCA by FePd+CMC the observed rate constants, kobs of TCE and 1,1,1-TCA are 0.0228 min-1 and 0.0076 min-1, respectively.