Electrochemically reactive nanobubbles (ERNBs): An innovative solution for advanced oxidation processes (AOPs) in pollutant degradation and CO2 utilization

Abstract

Advanced oxidation processes (AOPs) play a crucial role in degrading persistent pollutants, disinfecting water, and treating industrial effluents. However, their widespread application faces challenges such as high energy consumption, low mass transfer, reliance on chemical reagents, lack of reaction sites, and the formation of toxic byproducts. Nanobubble (NB) technology offers an innovative solution by offering a high gas-liquid interface, enhanced mass transfer, and improved radical generation. This study investigates the application of electrochemically reactive nanobubbles (ERNBs) as a novel and effective strategy for AOPs, focusing on the degradation of persistent organic pollutants such as tetracycline (TC). The ERNBs, composed primarily of $O_2$ and $H_2$ nanobubbles (NBs), were generated via water-splitting reactions at electrode surfaces. Their degradation potential was evaluated under varying operational parameters, including pH, electrolyte type and concentration, applied current, and initial pollutant concentration. Special emphasis was placed on the extended reactivity of ERNBs after generation, attributed to the formation of reactive oxygen species (ROS). The presence and role of ROS were examined using fluorescence spectroscopy, and the pollutant degradation mechanism was further elucidated through LC-MS-based identification of intermediates. In addition, the study explores the integration of $C{O}_2$ NBs as a sustainable alternative electrolyte, enabling simultaneous pollutant degradation and carbon utilization. The performance of ERNBs was validated in a complex synthetic wastewater matrix to assess their potential applicability in real-world scenarios. Overall, the findings support the development of ERNB-based AOPs as a promising and sustainable approach for wastewater treatment and environmental remediation.