Underwater plasma discharges for environmental remediation: Plasma chemistry, reactive species, reactor design, and processing challenges

초록

Underwater plasma discharge has gained immense importance as an innovative technology for water sterilization and treatment, environmental remediation, medical applications and industrial processing owing to its sustainability compared with conventional techniques. Over the past few decades the research on underwater plasma discharge has attracted considerable attention, resulting in significant advances in its applications, diagnostic techniques and experimental observations. This review article provides a comprehensive overview of underwater plasma discharge technologies, covering their generation mechanisms, breakdown processes, discharge types and associated physical and chemical fundamentals. Fundamental physical processes, including electrical breakdown, the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and their effects on plasma discharge stability are discussed. The basic science of plasma-liquid interactions including the formation and transport of plasma species, underwater plasma discharge models and related concepts are being explored. The advance environmental and water sterilization applications are also reviewed. To identify suitable and energy efficient systems for generating underwater plasma discharge various reactor designs, power supplies and electrode materials are critically discussed. The review also addresses the major challenges encountered in scaling laboratory-scale studies to practical large scale applications and presents possible solutions to overcome these limitations. Current and future potential applications of underwater plasma discharge are analyzed and the review concludes by identifying the existing scientific and technological gaps in underwater plasma discharge technology while providing pathways to bridge these gaps. This review is expected to serve as a valuable roadmap for future research and practical applications of aqueous plasma discharge.

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