Rapid Elemental Extraction from Ordered and Disordered Solutes by Acoustically-Stimulated Dissolution

Alkaline industrialwastes (e.g., slags: ordered crystalline solids,and fly ashes: disordered solids) represent abundant reservoirs ofelements such as silicon and calcium. Rapid elemental extractionsfrom these wastes, however, have often relied on the use of stoichiometricadditives (i.e., acids or bases). Herein, we demonstrate thatacoustic stimulation enhances the release of network-forming Si speciesfrom crystalline blast furnace slags and amorphous fly ashes at reactiontemperatures less than 65 & DEG;C. These additive-free enhancementsare induced by cavitation processes which reduce the apparent activationenergy of solute dissolution (E (a), kJ/mol)by up to 40% as compared to unstimulated conditions. Because of thereduction in the apparent activation energy, acoustic stimulationfeatures an energy intensity that is up to 80% lower in promotingdissolution, as compared to other additive-free methods such as enhancingthe solute's surface area, introducing heat, or convectivelymixing the solvent. Based on atomic topology analysis, we show thatthe reduction in apparent dissolution activation energy upon acousticstimulation scales with the number of weak topological constraintsper atom in the atomic network of the dissolving solute, independentof their ordered or disordered nature. This suggests that sonicationbreaks the weakest constraints in the solute's atomic network,which, in turn, facilitates dissolution. The results suggest the abilityof acoustic stimulation to enhance waste utilization and circularity,by enabling efficient resource extraction from industrial wastes.

Automated summary

The study demonstrates that acoustic stimulation can enhance the release of silicon species from industrial slags and fly ashes at low temperatures by reducing the apparent activation energy of solute dissolution. This method is more energy efficient and effective compared to traditional additive-dependent methods.