Optimization of a Cellular Glass Ceramic Produced from Water Potabilization Sludge for Structural and Chemical Applications

Abstract

Waste sludge generated in the potabilization of surface water is used to produce cellular materials by mixing with clay and firing at 1 250 °C. An iron-rich glassy matrix with crystals of mullite and albite is formed. Porosity is generated by the slow release of H2O, which originates from the dehydroxilation of lepidocrocite at high temperature. The sludge/clay ratio and the sludge granulometry determine the properties of the product: from highly porous cellular foams to denser materials with high strength. Laboratory tests for both kinds of products show that the latter can be used as aggregates for low-density structural concrete. The former serve as a support material for the catalytic reduction of NOx in exhaust gases. Deposition conditions for Fe- and Pt-nanoparticles are optimized by experimental design, resulting in NOx-conversion rates close to 100%.