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)

In this study, we evaluate for the first time the effect of ionic composition on the anodic production of hydroxyl radical ( • OHa) during electrocoagulation (EC) process in batch using carbon steel electrodes. Likewise, hydroxyl radical production from active chlorine ( • OHph) electrogenerated in EC photoassisted with UVA (λ = 365 nm) and UVC light (λ = 254 nm) was evaluated using car wash wastewater. Both, • OHa and • OHph, were analyzed by UV-Vis spectroscopy and fluorescence using coumarin as the probe. Under optimal conditions (j = 8 mA cm -2 , 25 °C, 15 min, 6 rpm), turbidity, suspended solids and color were removed by 98.3%, 98.7% and 93.1%, respectively. However, total organic carbon (TOC) abatement only attained 27%. This can be related to the fact that • OHa and • OHph were not identified during EC, with or without UV irradiation. Hence, the organic matter is mainly removed by coagulation with Fe(OH)n species. Comparative treatment of the same wastewater by electrochemical oxidation (EO) with a Ti|IrO2-Ta2O5 anode in the presence of electrogenerated active chlorine and UVC light demonstrated the generation of • OHph, thus encouraging the potential coupling of EC with EO.

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During the crude oil refining process, NaOH solutions are used to remove H2S, H2Saq, and sulfur compounds from different hydrocarbon streams. The residues obtained are called “spent caustics.” These residues can be mixed with those obtained in other processes, adding to its chemical composition naphthenic acids and phenolic compounds, resulting in one of the most dangerous industrial residues. In this study, the use of electrochemical technology (ET), using BDD with Ti as substrate (Ti/BDD), is evaluated in electrolysis of spent caustic mixtures, obtained through individual samples from different refineries. In this way, the Ti/BDD’s capability of carrying out the electrochemical destruction of spent caustics in an acidic medium is evaluated having as key process a chemical pretreatment phase. The potential production of•OHs, as the main reactive oxygen species electrogenerated over Ti/BDD surface, was evaluated in HCl and H2SO4through fluorescence spectroscopy, demonstrating the reaction medium’s influence on its production. The results show that the hydrocarbon industry spent caustics can be mineralized to CO2and water, driving the use of ET and of the Ti/BDD to solve a real problem, whose potential and negative impact on the environment and on human health is and has been the environmental agencies’ main focus.

This document contains a short summary of the development of a highly efficient one-step technique which was carried out to obtain long and aligned carbon nanotubes with or without Fe filling. The aligned carbon nanotubes (CNTs) were synthesized by microwave (MW) irradiation heating from a ferrocene Fe(C 5 H 5 ) 2 . In this research, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) are used for study the growth of aligned carbon nanotubes by microwave heating. As a contribution of this method, the aligned multi-layer carbon nanotubes were obtained. CNTs have a metal particle at the tip of each tube. This carbon nanostructure promises to become important in fuel cells and in nanoscale engineering of other systems in which electrical effects, mechanical and chemical interactions are integrated to produce macroscale.