Synthesis and characterization of zeolite A from crushed particles of aluminoborosilicate glass used in LCD panels

We tried to synthesize zeolite from the sand-like particles of crushed LCD panel glass collected from discarded electronics devices. In the previous study, zeolite A was synthesized using fine glass particles of <10 μm. Acid treatment was found effective toward synthesizing single phase zeolite A. Using sand-like coarse glass particles, of which the internal-core consists of glass and the surficial shell transforms into zeolite, we investigated the effect of acid-treatment by evaluating the surface of the coarse glass particles. Under acid-treatment, components other than Si eluted from the glass. The elution amounts were several percent of the total glass mass. After acid-treatment, the surface of the glass particle was discovered to be covered in a thin layer of poor components other than Si and a relatively rich quantity of Si, by scanning electron microscopy and energy dispersive spectrum analysis. The synthesized zeolite A increased the longer the acid-treatment time, which suggest the thin layer increased. When the concentration of the acid solution decreased, glass components other than Si dissolved well, and the synthesized zeolite A increased as a result. This indicates that the Si-rich layer is necessary for preferential synthesis of zeolite A from crushed particles of aluminoborosilicate glass.