Removal of Dyes from Wastewater using the Residue from the Chemical Recycling of Glass Cullet

The unextracted residue, obtained after an extractive process from glass cullet with sodium hydroxide aqueous solution at 140°C for 2 hours, is mainly made of calcium and sodium silicate. It shows a high porosity and a large surface area. It could be active as an agent for the removal dyes from wastewater. In this paper Methyl Red (MR) was employed to evaluate the adsorbent properties of above residue. Aliquots of this residue were maintained at room temperature under constant stirring with 0.025-0.5 g/L of MR aqueous solution by using a liquid/solid ratio from 50 to 500 mL/g and up to 24 hours. The results have shown an effective removal of MR within one hour for MR concentration of 0.5 g/L and within 30 minutes and for MR concentration ≤ 0.25 g/L with liquid/solid ratio < 100 mL/g. The performance of the residue as an adsorbent contributes to increase the environmental sustainability of glass recycling treatment and further decreases the amount of waste to be delivered to landfill.