Exploring the potential of ultrasound in hydrogen production from organic-contaminated water

The transition toward renewable energy systems is a key challenge for climate change mitigation and global energy security. In this context, hydrogen (H2) is widely recognized as a promising energy vector due to its high gravimetric energy density and carbon-free end use. However, despite its potential, only c.a. 4% of the global hydrogen production currently originates from renewable pathways such as water electrolysis, mainly due to efficiency losses and high energy demands associated with aqueous-phase processes, particularly when operating in complex media such as wastewater. At the same time, wastewater streams contain significant amounts of organic pollutants that represent an environmental concern. Coupling hydrogen production with the electrochemical oxidation of organic contaminants offers an attractive strategy to simultaneously reduce energy demand and promote wastewater treatment [1]. However, such integrated systems are often constrained by mass transport limitations, gas accumulation phenomena, and slow reaction kinetics, which negatively affect both hydrogen generation and pollutant degradation. To overcome these limitations, the application of power ultrasound has emerged as a powerfull process intensification tool. Ultrasonic irradiation induces acoustic cavitation, generating localized extreme conditions that promote water sonolysis and the formation of highly reactive radical species [2]. These radicals actively participate in the oxidation of organic pollutants, enhancing electro-oxidation pathways beyond conventional diffusion-controlled regimes. In parallel, ultrasound-driven physical effects, such as acoustic streaming, micro-mixing, and boundary layer disruption, significantly improve mass transport, facilitating reactant accessibility and accelerating product removal [2]. In this study, the effect of ultrasound on both the electro-oxidation of organic pollutants and the simultaneous hydrogen production in acidic aqueous media will be investigated. By improving reaction kinetics, alleviating mass transport constraints, and enabling wastewater valorization, ultrasound-based technologies offer a viable pathway toward energy-efficient and sustainable systems aligned with circular economy principles and global decarbonization goals. References [1] Falletta, E. et al., J. Env. Chem. Eng., 12, 113139 (2024). [2] Galloni, M.G. et al., Curr. Opin. Chem. Eng., 48, 101129 (2025).