High-density polyethylene membrane containing Fe⁰ as a contaminant barrier

To improve the performance of polymer-based containment barriers with respect to the breakthrough of chlorinated solvents, a high-density polyethylene (HDPE) membrane containing zero-valent iron (Fe⁰) nanoparticles was developed as a reactive barrier. The performance of the reactive membrane was evaluated by challenging it with carbon tetrachloride in a diaphragm cell apparatus. In a Fe⁰/HDPE system, reaction between carbon tetrachloride and Fe⁰ did not occur due to a lack of water in the polymer matrix. A glycerol-modified Fe⁰/HDPE membrane successfully increased the lag time before breakthrough by 13-16 fold compared to HDPE alone. Calculations estimate that only 2.5-3.0% of the Fe⁰ initially present in the membrane reacted before breakthrough of carbon tetrachloride. Extrapolations of these results to practical situations with larger membrane thicknesses and lower contaminant concentrations predict lag times on the order of years.