Temperature Effects on PCE Degradation on ZVI in Column Experiments with Deionized Water

Abstract

The effects of rising groundwater temperatures on zerovalent iron (ZVI)-based remediation techniques will be critical in accelerating chlorinated hydrocarbon (CHC) degradation and with three ZVIs widely used in permeable reactive barriers (Gotthart-Maier cast iron [GM], Peerless cast iron [PL], and ISPAT sponge iron [IS]) was evaluated at 10-70 degrees C in deionized water. From 10 to 70 degrees C, PCE degradation half-lives decreased from 25 +/- 2 to 0.9 +/- 0.1 h (PL), 24 +/- 3 to 0.7 +/- 0.1 h (GM), and 2.5 +/- 0.01 to 0.3 +/- 0.005 h (IS). Trichloroethylene (TCE) degradation half-lives at PL and GM decreased from 14.3 +/- 3 to 0.2 +/- 0.1 h (PL) and 7.6 +/- 2 to 0.4 +/- 0.1 h (GM). This acceleration of CHC degradation and the stronger shift toward reductive fl-elimination reduced the concentration of potentially harmful metabolites with increasing temperatures. PCE and TCE degradation yields an activation energy of 28 (IS), 58 and 40 kJ mol-1 (GM), and 62 and 53 kJ mol-1 (PL). Hydrogen gas production by ZVI corrosion increased by 3 orders of magnitude from 10 to 70 degrees C, and an increased chance of gas clogging was observed at high temperatures.