Treatment of Pentachlorophenol (PCP) is challenging due to its hydrophobic nature and the stability of the carbon-chlorine bond, particularly in aromatic molecules. Zero Valent Iron (ZVI) has been used as an effective in situ passive treatment process for PCP contaminated groundwater. However, ZVI applications can experience a decrease in degradation rates over time due to: ZVI surface passivation, the formation of non-conducting iron oxides on the ZVI surface, and the accumulation of less chlorinated intermediates. In this study, ZVI modification by acid washing and formation of bimetallic systems by the incorporation of Nickel (Ni) was explored to overcome these limitations.

PCP degradation was investigated in batch tests using ZVI as received (unwashed or UW) and acid washed (AW) ZVI. Two forms of bimetals were tested - one in which the Ni powder and ZVI (UW or AW) were physically mixed (NiS/Fe) and the other in which the Ni was coated onto acid washed ZVI (NiC/Fe) by reacting ZVI with NiSO4 solutions. PCP dechlorination was confirmed by gas chromatography quantifying PCP and all intermediates formed. Raman spectroscopy was used to characterise the ZVI surfaces.