Nanoscale, zero valent iron particles for application as oxygen scavenger in food packaging

- Nanoscale iron reacts in dry and humid conditions with oxygen.
- The reaction rate is higher at 100% relative humidity compared to dry conditions.
- Nanoscale iron can be dispersed in polymers.
- Nanoscale iron can be an active component of oxygen scavenging composites.

Oxygen scavengers which are based on oxidation of iron powder dispersed in a polymer matrix are established in the packaging industry. They protect foods from oxygen. The iron particles have a diameter of several micrometers, which is too high to allow thin layers in multilayer film structures. A promising alternative is a developed nanoscale oxygen scavenger which is subject of this study. The aim of this study was to evaluate the oxygen absorption rate and the oxygen absorption capacity of nanoscale iron at 100% relative humidity and at dry conditions.Nanoscale oxygen scavengers (zero valent iron particles) were synthesized. Their reactivity was tested. Furthermore, they were blended with a silicone matrix. The nanoscale oxygen scavenger absorbed oxygen in wet (100% relative humidity) and dry conditions. At 100% relative humidity the reaction rate of the powder was two to three times higher compared to non-nanoscale iron powder. The absorption rate of the nanoscale iron dispersed in a silicon carrier was at least ten times higher at 100% relative humidity compared to a commercially available iron based oxygen scavenger in a polyethylene or polypropylene polymer matrix.