A Polymer Membrane Containing Fe⁰ as a Contaminant Barrier

A poly(vinyl alcohol) (PVA) membrane containing iron (Fe⁰) particles was developed and tested as a model barrier for contaminant containment. Carbon tetrachloride, copper (Cu²⁺), nitrobenzene, 4-nitroacetophenone, and chromate (CrO₄^2-) were selected as model contaminants. Compared with a pure PVA membrane, the Fe ⁰/PVA membrane can increase the breakthrough lag time for Cu ²⁺ and carbon tetrachloride by more than 100-fold. The increase in the lag time was smaller for nitrobenzene and 4-nitroacetophenone, which stoichiometrically require more iron and for which the PVA membrane has a higher permeability. The effect of Fe⁰ was even smaller for CrO ₄^2- because of its slow reaction. Forty-five percent of the iron, based on the content in the dry membrane prior to hydration, was consumed by reaction with Cu²⁺ and 15% by reaction with carbon tetrachloride. Similarly, 25%, 17%, and 6% of the iron was consumed by nitrobenzene, 4-nitroacetophenone, and CrO₄^2-, respectively. These percentages approximately double when the loss of iron during membrane hydration is considered. The permeability of the Fe ⁰/PVA membrane after breakthrough was within a factor of 3 for that of pure PVA, consistent with theory. These results suggest that polymer membranes with embedded Fe⁰ have potential as practical contaminant barriers.