Abstract
The scientific understanding and demonstration of the immobilization of heavy metals (notably lead and chromium) in food contact materials is crucial for the safety of the environment and humans. To tackle this issue lead crystal glasses doped between 50 and 2000 ppm of Cr2O3 were altered under severe aqueous alteration conditions (acetic acid 4%, pH 2.4, 70 °C, 330 days). The increase in Cr leads to a decrease in the Pb release into the solution. The leached Cr content was lower than Pb, itself much lower than alkalis. Structural characterization before and after alteration shows the presence of Cr(III) exclusively, with no redox changes in the course of alteration. Cr and Pb are partially retained during alteration near cationic domains, which are less accessible to protonated species. Cr favors the Si recondensation in the rich non-bridging oxygen (NBO) mixing sites, leading to an increase of glass polymerization within the altered layer.