Porous waste glass for lead removal in packed bed columns and reuse in cement conglomerates

A porous waste glass (RWPG = recycled waste porous glass) was used in wastewater treatments for the removal of lead ions from single, binary, and ternary metal solutions (with cadmium and nickel ions). Experiments were performed in columns (30 cm3, 10 g) filled with 0.5-1 mm beads till complete glass exhaustion (breakthrough). In the case of single and binary solutions, the columns were percolated at 0.2 Lh-1 (2 mg Me+2 L-1); in the case of ternary solutions, the columns were percolated at 0.15-0.4 Lh-1 (2 mg Me2+ L-1) and with 2-5 mg Me2+ L-1 influent concentration (0.2 Lh-1). Lead ions were removed mainly by ion exchange and also by adsorption. From a kinetic point of view, the rate controlling step of the process was the interdiffusion of the lead ions in the Nernst stationary liquid film around the sorbent. The uptake of the metals and the glass selectivity were confirmed by Energy Dispersive X-ray spectroscopy (EDX) analysis. After lead retention process, glass beads were reused as lightweight aggregates for thermal insulating and environmental safe mortars.