Electro‐oxidation of amoxicillin using titanium electrodes electrophoretically coated by iridium or ruthenium with tantalum oxides

Abstract

BACKGROUND Amoxicillin (AMX) is one of the pharmaceutical compounds in waters being targeted in wastewater decontamination studies, and some of the technological alternatives to degrade it involve using modified surfaces with transition metal oxides, such as IrO2/Ta2O5|Ti and RuO2/Ta2O5|Ti, for in situ production of hydroxyl radical (•OH) to oxidize AMX in aqueous media. RESULTS The IrO2/Ta2O5|Ti 70:30 electrode was best suited for AMX electro‐oxidation, with 99.23% removal measured by HPLC‐UV–Vis, 81.13% by COD removal, and current efficiency of 41.1% in 0.1 mol L–1 Na2SO4 after applying 15 mA for 6 h. These results are due to a larger surface area (251.67 cm2) and a higher amount of •OH radicals being generated by cm2 in neutral pH (3.8 mol L–1 cm−2) compared to the other electrodes. CONCLUSION This paper shows the simulation of the experimental data regarding the complete degradation of AMX (100%) by HPLC, comparing the experimental results and simulation results for AMX degradation using the IrO2/Ta2O5|Ti 70:30. The modeling predicts and validates the disengagement of COD obtained experimentally, considering the mechanism proposed by Trovó and collaborators for the electro‐oxidation of AMX to product C6 (C16H22N3O7S) by generating •OH. © 2020 Society of Chemical Industry (SCI)

Electrochemical degradation of amoxicillin in acidic aqueous medium using TiO2-based electrodes modified by oxides of transition metals

“…6) with 0.25, 0.20 and 0.12 mA cm -2 for 1.45 V vs. Ag|AgCl 3M NaCl. These results indicate that Ta is necessary to be present in this kind of electrode to increase the electronic transference as they are modi ed in this study, despite Ta does not participate in the redox process (Comninellis and Vercesi 1991), it is only a protonic conductor (León et al 2020).…”

“…The Ru-Ta and Ir-Ta ratios employed in the precursors' solutions were 100:0, 30:70, 50:50, 70:30 and 100:0 v/v in a two electrodes electrochemical cell, where the Ti plate or cylinder was the working electrode with a Ti plate or mesh as counter-electrode, respectively (Fig. 1), which were used in the electrodeposition as it has been reported before (Herrada et al 2018(Herrada et al , 2020León et al 2020). After electrophoretic deposition of Ru-Ta and Ir-Ta with the different ratios, the synthesis of metal oxides was obtained in two-step thermal decomposition, 523 K for 10 min, and 723 K for 1 h (Herrada et al 2018(Herrada et al , 2020León et al 2020).…”

“…The AMX electrochemical oxidations were performed using a Ti cylinder naked and modi ed with Pb, Ir, Ru and Ta to have Pb-Ta 30:70, Pb-Ta 70:30, Ru-Ta 30:70, Ru-Ta 70:30, Ir-Ta 30:70, and Ir-Ta 70:30 as an anode, with a Ti mesh cathode around it (León et al 2020). With the same con guration of the electrochemical cell and the different naked and modi ed electrodes, the corresponding hydrodynamic curves were made using 0.1 mol L − 1 H 2 SO 4 in the presence of 10 mg L − 1 AMX (Across Organics) at 300 rpm using a two-electrode cell arrangement in presence of Ti mesh and the naked and modi ed Ti cylinders as counter and the working electrode, respectively.…”

“…10). In the last case, Ta is important for the electrocatalyst effect of Pb since Ta is a protonic conductor and is favorable to generate interfacial hydroxyl radicals for the electrocatalysis effect (León et al 2020). In this case, Pb-Ta 50:50 showed the major current density (0.5 mA cm -2 ) followed by Pb-Ta 70:30 (0.48 mA cm -2 ); Pb-Ta 30:70 showed the lowest current density (0.35 mA cm -2 ).…”

“…Advanced oxidation process (AOPs) with modi ed electrodes are other promise technology, which shows high removal percentages of pharmaceutical compounds as paracetamol (Brillas et al 2005) AOPs are used the dimensional stable anodes (DSA ® ), which are constructed by a thin lm of transition metal oxides over metal as titanium (Ti) by its low cost; the Ti is sandblasted to increase the exposed area to include the metallic oxides, as it has been reported previously (Herrada et al 2016(Herrada et al , 2018(Herrada et al , 2020León et al 2020).…”