Hypochlorous acid electrosynthesis and service life assessment of a Ti|Ti-Ru-Ir-oxides anode assembled in a flow electrolyzer: Understanding the influence of the concurrent O bubbling flow.

This paper addresses the influence of bubbling flow and service life of the Ti|Ti-Ru-Ir-oxides anode during the electrosynthesis of HClO in a laboratory-scale filter-press-type electrolyzer. The electrolyzer was assembled in a flow plant in recirculation mode. Polarization curves in rotating disk electrode (RDE) revealed the coexistence of the oxygen evolution reaction (OER) during HClO electrosynthesis in diluted chloride solutions (containing 35 mM NaCl at pH 3). CFD simulations of the two-phase (O-HO) flow were obtained by solving simultaneously the Navier-Stokes and charge conservation equations using a finite element method code. The O-HO simulations show the efficient gas release in the electrolyzer provoked by the continuous phase (HO) inertia and the well-engineered cell design. The moderated O dispersion caused a quasi-homogeneous current distribution along the anode. However, the current efficiency during HClO electrosynthesis gave values of ∼32% provoked by the OER on the anode. The HClO accumulations (from 3.02 to 6.64 mM) showed excellent agreement with CFD simulations. The accelerated life tests revealed that the Ti | Ti-Ru-Ir-oxides anode has a lifetime of at least 26 years during the HClO electrosynthesis in diluted chloride solutions.