Ti|Ir–Sn–Sb oxide anode: Service life and role of the acid sites content during water oxidation to hydroxyl radicals

Abstract

This work describes the preparation of four Ti|Ir-Sn-Sb oxide anodes by the Pechini method under different conditions and the evaluation of their service life, envisaging a future application in electrochemical advanced oxidation processes for water treatment. This was estimated by means of accelerated life tests (1 A cm-2 , 1 M HClO4), which highlighted the dependence of durability on the Ir and Sn content in the mixed metal oxide (MMO) as well as on the required heat treatment time for its preparation. The best MMO anode reached up to 351 h of service life under such extreme conditions. SEM-EDS and XRD analyses were performed before and after the accelerated life tests, evidencing that the failure of the MMO coatings occurred by detachment from the titanium substrate, thus losing the anode electroactivity. Great amounts of acid sites in the range 0.21-0.26 meq g-1 were determined on the MMO surfaces by Boehm titrations. From the apparent rate constants determined for the decay of N,N-dimethyl-4-nitrosoaniline used as spin trap, before and after acid sites neutralization, a higher activity of adsorbed hydroxyl radicals at the MMO surface cannot be correlated with a greater amount of acid sites. The results obtained suggest that other active sites affect the formation of such radicals from water discharge.

Mineralization of Methyl Orange azo dye by processes based on H2O2 electrogeneration at a 3D-like air-diffusion cathode

“…1). It was equipped with a Ti|Ir-Sn-Sb oxide anode, manufactured following the Pechini method according to our recently reported procedure (Aguilar et al, 2017(Aguilar et al, , 2018. Its dimensions of breadth (3.0 cm) and length (8.0 cm) conferred a total area of 24 cm 2 that contacted with the liquid phase.…”

Enhanced Photocatalytic Activity of TiO2 Modified with GaI toward Environmental Application

“…This faster degradation of the acid violet 63 contaminants was associated with the high production of hydroxyl radicals on the surface of Ga-TiO 2 nanocomposite material during photocatalysis. The ability to generate oxidizing species ( • OH) of 0.3% Ga-TiO 2 nanocomposite was investigated by preparing 10 μM of pNDA ( N , N -dimethyl- p -nitrosoaniline) solution, as it was the well-known radical scavenger (spin-trap), , hydroxyl radical, generated during the photocatalytic reaction and detected by measuring the absorbance at λ max = 440 nm of pNDA working solution. The experimental setup follows a similar photocatalytic condition (10 mg 0.3% Ga-TiO 2 ; 10 μM pNDA), as mentioned above in the decolorization experiment under UV irradiation.…”

Electrosynthesis of hydrogen peroxide sustained by anodic oxygen evolution in a flow-through reactor

“…The reactor consisted of two rectangular ABS end plates, whereas the electrolyte flow channel was embedded in between. As can be observed in Fig 1b, the electrolyte flow channel contained two sets of three Ti|IrO2-Ta2O5 meshes, manufactured by the Pechini method [27], and two porous RVC pieces (Goodfellow, 60 pores per inch (ppi)). Both, anodes and cathodes had the same dimensions (1.5 cm length × 3.0 cm breadth × 0.5 cm thickness).…”