Reductive dechlorination of polychlorinated biphenyls (PCBs) by means of Nanoscale Zero Valent Iron (NZVNI) particles

Polychlorinated biphenyls (PCBs) are toxic and recalcitrant compounds that can be reductively dechlorinated in the presence of expensive catalyzers, such as bimetallic Fe/Pd nanosized particles. Other Pd-free zerovalent metallic and bimetallic systems, such as Nanoscale Zero Valent Iron (NZVI) and Nanoscale Zero Valent Nickel-Iron (NZVNI) particles, are cheaper and able to promote the dechlorination of aliphatics and aromatics. In this paper, we investigated the dechlorination capability of NZVI (1.67g Fe0/L) and NZVNI (1.67g Fe0/L and 0.88g Ni0/L) particles towards 2,3,4,5-CB (2 mg/L) in water and methanol/water 30% (v/v) solution at room temperature. NZVI proved ineffective in 2,3,4,5-CB dechlorination under both the above-mentioned conditions. On the contrary, NZVNI dechlorinated 7.1±1.8 % and 27.7±0.4 % of the 2,3,4,5-CB occurring in water and in methanol/water solution, respectively, in 8 weeks of incubation. Dechlorination occurred via preferential removal of the less sterically hindered chlorine in meta position 5 and proceeded by removing chlorines in para position and in meta position 3