Titania-Based Sonocatalysts for Water Remediation: A Critical Evaluation of Mechanisms, Performance, and Its Niche among Advanced Oxidation Processes

Abstract

Growing industrial discharge of persistent organic pollutants threatens ecosystems and health, necessitating effective water remediation. Among advanced treatments, sonocatalysis shows promise but critically lacks rigorous benchmarks and a clear strategic rationale against established methods like photocatalysis. This review addresses this critical gap by correlating the electronic and structural engineering of TiO₂ composites with their sonocatalytic activity. Most significantly, this work introduces a novel comparative framework, employing normalized kinetic metrics, specifically, the mass-normalized reaction rate (mmol g⁻¹ min⁻¹) and the specific removal rate (L g⁻¹ min⁻¹), to objectively benchmark sonocatalysis against conventional and advanced photocatalysis. Our analysis delineates two distinct technological pathways. Sonocatalysis demonstrates definitive superiority in niche applications involving turbid, light-impenetrable, or highly concentrated industrial effluents, where its ultrasonic activation mechanism overcomes the fundamental limitation of photocatalysis. Conversely, advanced photocatalytic heterojunctions and hybrid systems offer greater energy efficiency and broader applicability for treating large volumes of less challenging wastewater.