In Situ Monitoring of Hypochlorite Decay under Radiation Using Differential Pulse Voltammetry

High Resolution Image Download MS PowerPoint Slide Understanding how concentrations of corrosive oxidants evolve under γ-radiation is essential for assessing long-term material performance in nuclear environments. This work integrates in situ differential pulse voltammetry (DPV) with finite-element kinetic modeling to track and interpret the decay of hypochlorite (OCl – ) in aerated 0.1 M NaCl at pH ∼9.9 under a dose rate of 725 Gy h –1 . Using a three-electrode setup inside a 60 Co γ-cell, OCl – was quantified from calibration curves, where concentrations were validated ex situ by UV–vis spectroscopy. For an initial OCl – added concentration of 10 mM, both methods showed a decrease to ∼1 mM after 24 h. Kinetic analysis based on a radiolysis/halogen reaction scheme indicates that HOCl consumption is dominated by OH • abstraction (∼71%), with a secondary contribution from O 2 •– reduction (∼22%) and a minor Cl – -mediated pathway (∼7%); contributions from e – and H • are negligible at the steady state. The added HOCl drives a pronounced rise in OCl • that feeds back to lower the steady-state OH • level and modulates H 2 O 2 formation. From these kinetics, it is estimated that g HOCl ≈ −0.53 μmol J –1 . Beyond validating DPV as an in situ radiation electroanalytical method, the combined measurements and modeling provide a mechanistic basis for OCl – transformation in saline waters, establishing a general radiation-electrochemistry platform for time-resolved detection of radiolysis products relevant to nuclear-waste containment.