Reply to comment on, hydroxyl radical scavenging by solid mineral surfaces in oxidative treatment systems: Rate constants and implications. water research 169, 9. 10.1016/j.watres.2019.115240.

The comments (Kopinke, 2020) do not accurately represent the experimental conditions, parameter values, and conceptual model used in our study (Rusevova and Huling, 2020), leading to a misinterpretation of the results. The kinetic analysis used to determine the surface scavenging rate constant (k) involved competition kinetics between the probe and the mineral surfaces (Rusevova and Huling, 2020); similar competition kinetic methods have been used regarding other widely reported rate constants (Buxton et al., 1988; Dorfman and Adams, 1973). Assuming mass transport limitations prevented ·OH reaction at mineral surfaces, as proposed in the comments, estimates of k would be very small, or 0. However, the addition of solid phase media was found to effectively and consistently compete with the probe. The propensity of data, supporting data, and high degree of quality assurance and quality control measures provide multiple lines of evidence indicating a high level of certainty that ·OH scavenging occurred by solid surfaces.

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