Beyond the Bench: Evaluating the Reliability of Chemical Scavengers in Radical-Based Advanced Oxidation Processes

Abstract

Chemical scavengers are frequently used to quantify the contribution of target radicals to contaminant removal in natural and engineered waters. While favored for their ease of use and versatility across systems, improper selection can lead to significant kinetic and mechanistic misinterpretations. This study presents a critical evaluation of chemical scavengers in radical-induced reactions across various environmental scenarios. Specifically, we demonstrate that in systems containing both target and coexisting radicals, commonly used scavengers can react with both species, complicating the measurement of reaction kinetics and leading to misinterpretation of target radical contributions. In addition, we discuss the challenges associated with applying scavengers in heterogeneous systems, where the distribution of scavengers and target compounds across interfaces significantly impacts the evaluation of radical contributions. Further, our insights from non-steady-state systems into radicals’ dynamic behavior and transient phenomena are often overlooked in other steady-state conditions. We address interactions between scavengers and triplet excited-state compounds in photochemical systems, emphasizing the importance of selecting appropriate scavengers to ensure accurate kinetic profiling and radical quantification. These findings hold significant implications for advancing scavenger research across a broad range of chemical research and practical applications.

Keywords: chemical scavenger, radical contribution, heterogeneous system, triplet excited state