Ultrasonic coal-wash for de-sulfurization

► Coal will continue to be a major fuel source for the foreseeable future, but its use is limited by ash and sulfur impurities. ► Cost-effective, high-throughput removal of ash and sulfur remain critical challenges in coal processing. ► This study explores aqueous and solvent-based ultrasonic techniques for deashing and desulfurization. ► Process optimization and scale-up strategies are outlined.