Fabrication of glass-based products as remediation alternative for contaminated urban soils of Barcelona

Abstract

Contaminated soils from an area previously occupied by a metal smelting industry of Barcelona city were used as raw material for making glass. Vitrification was investigated as a possible remediation technique. The main pollutants in these soils are Cu, Pb and Zn. Glass was formulated using 80 wt% of soil and 20 wt% of Na2CO3. The mixture was molten at 1450 °C. Crystallisation temperatures, obtained by Differential Thermal Analysis, were 790 °C, 842 °C and 879 °C. Nepheline, diopside and rhönite crystallized from glass treated at exothermal peaks. The endothermic peak at 1259 °C corresponds to the melting temperature. Glass transition temperature, determined by dilatometry was 632 °C. Viscosity-temperature curve was used to calculate the relevant temperatures for the process. The conformation range is between 995 °C and 1298 °C, and the workability interval ranges from 1293 °C to 1302 °C. The contents of the elements leached from the glass are well below the limits established by the European legislation. Thus, the vitrification is an effective remediation technique for contaminated soils.