Mitigation of Leachates in Blast Furnace Slag Aggregates by Application of Nanoporous Thin Films

Abstract

The reutilization of slag materials as aggregates is seriously limited by the production of contaminant leachates rich in heavy metals and sulfur when these materials are contacted by water. A unique type of thin-film nanotechnology was used to ameliorate this problem. The surface of the slag was altered by depositing a thin-film comprised of nanoporous oxides. The deposition was performed by coating the aggregates with a suspension containing nanoparticles. Once the water evaporated, a nanoporous thin-film (<0.5 mu m) remained firmly attached to the surface of the slag. Different leachate experiments under semi-anoxic conditions were performed using three different nanoparticles oxides films including silica, and titanium. These films were compared against a control. The preliminary results demonstrated that samples coated with one layer of these oxides can decrease the amount of sulfur and calcium in the leachate by 70 and 80%, respectively.