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

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 degrees C. Crystallisation temperatures, obtained by Differential Thermal Analysis, were 790 degrees C, 842 degrees C and 879 degrees C. Nepheline, diopside and rhonite crystallized from glass treated at exothermal peaks. The endothermic peak at 1259 degrees C corresponds to the melting temperature. Glass transition temperature, determined by dilatometry was 632 degrees C. Viscosity-temperature curve was used to calculate the relevant temperatures for the process. The conformation range is between 995 degrees C and 1298 degrees C, and the workability interval ranges from 1293 degrees C to 1302 degrees 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.

Automated summary

Contaminated soils from a metal smelting industry area were used to make glass by vitrification as a remediation technique, with main pollutants being Cu, Pb, and Zn. The appropriate ratio of soil and Na2CO3, as well as key crystallization temperatures obtained from thermal analysis, were crucial in the process. The effectiveness of the method was confirmed by the low leached element contents in the glass compared to European legislation limits.