Heavy metal release from irradiated LDPE/nanometal composite films into food simulants

Low-density polyethylene (LDPE) films containing three types of nanometals (ZnO, Cu, or Ag) were prepared and characterized. A release experiment was carried out on the nanocomposite films subjected to three treatments: no irradiation, gamma irradiation with solvent contact (10 kGy), and gamma irradiation without solvent contact. The release of heavy metals from the nanocomposite films into three types of solvents (water, 95 % ethanol, and 3 % acetic acid) was recorded at room temperature. In general, gamma irradiation was likely to promote the release of heavy metals. The release amount of heavy metals depended on the type of nanometal and solvent. An increase in release amount of Zn and Cu was observed in 95 % ethanol and Ag in all types of solvents at the end of the experiment after the film samples were treated with gamma irradiation (with solvent contact during irradiation). The increase in heavy metal release was attributed to the accelerated surface oxidation of nanometals after irradiation, as confirmed by XPS analysis on the irradiated Ag powders.