Influence of AlN, TiN and SiC reduction on the structural environment of lead in waste cathode-ray tubes glass: an x-ray absorption spectroscopy study

This paper reports an x-ray absorption spectroscopy (XAS) analysis of the local structure around lead contained in foam glasses prepared with waste funnel cathode-ray tube glasses (CRT) and three reducing agents AlN, TiN and SiC. The XAS data were collected at the Pb-L(III) edge to measure the influence of the reducing agent concentration on the unreduced lead content present in the glass. XANES spectra have been demonstrated to be a linear combination of both pure metallic lead and funnel glass spectra, with a significant modification of the funnel spectra for the highest contents of reducing agent. We have shown that the average coordination number of lead decreases in the case of TiN and SiC but remains constant in the case of AlN. The coordination number was found to be more affected for TiN than for SiC. Nevertheless, Pb-O bond lengths were determined to be constant close to 2.23 angstrom whatever the reducing agent and its content.