ISCR is an advanced environmental remediation technique that treats contaminated soil and groundwater by introducing a reductant or reductant-generating material into the subsurface, allowing the reduction of targeted contaminants to safe levels. Among the most effective reductants, Zero-Valent Iron (ZVI) is known for its effectiveness in removing a wide range of persistent organic compounds (mainly chlorinated aliphatic hydrocarbons, PCBs, and pesticides) by breaking them down into harmless end products. ZVI also treats inorganic contaminants (especially heavy metals), through precipitation and sorption processes. In particular, ZVI is extensively employed for the remediation of chlorinated ethenes. The reductive dechlorination of chlorinated ethenes follows two primary pathways: - Abiotic Degradation – It is the dominant degradation pathway in presence of ZVI, which donates electrons, breaking down contaminants through β-dichloroelimination. This process minimizes the formation of harmful intermediates like vinyl chloride. - Biotic Degradation – This biological process is sustained by molecular hydrogen (H2) generated by ZVI in water. This H2 serves as an electron donor, enhancing microbial activity and facilitating the stepwise replacement of chlorine (Cl) atoms by hydrogen through enzymatic reactions.
