Glyphosate is one of the most widely used herbicides in various crops. Based on the existing literature, this herbicide has carcinogenic characteristics, being able to be found in water courses, not only for its leaching in soils, but also in the effluents of the industries that produce it. Due to its negative impact on living beings, this work aims to investigate the applicability of the electrochemical treatment of a synthetic solution containing glyphosate with boron-doped diamond anode. Two electrochemical systems were tested (magnetic stirring and recirculation flow) for studying the applied current density (j = 30-200 mA cm-2), initial glyphosate concentration (250-850 mg L-1) and initial pH (3-9) as operating conditions. Best removal efficiencies were achieved at 100 mA cm-2, 850 mg L-1 of glyphosate and the natural effluent pH (≈5,0). The performance of the electrochemical systems was evaluated in terms of removal of chemical oxygen demand (COD) and energy requirements. After 120 min of treatment, comparing the magnetic stirring system to the recirculation it was verified that the first one is the most economically viable with an energy consumption of 56 kWh m-3. However, the results at both electrochemical systems are more efficient than those reported in the literature when the initial concentration, time and mass transport coefficient are considered.

Boron doped diamond films (BDD) are the most studied electrocatalytic materials and their efficiency for removing organic compounds is attributed to their ability to produce a large amount of hydroxyl radicals by the electrolysis of water. However, some organic compounds are easy to degrade than others, as well as they also interact with BDD surface. Thus, it is necessary to understand the chemical/electrochemical process at the molecular level. In this frame, this work aims to study the electrochemical oxidation (EO) of oxalic acid (OA) at BDD anode, understanding the reaction mechanism, formation of hydroxyl radicals, the effect of supporting electrolyte concentration, and the role of oxidants in solution taking into consideration the cyclic and linear voltammetric measurements. Voltammetric results clearly reveal that a direct electron transfer is achieved as the main mechanistic behavior suffered by OA on BDD surface before oxygen reaction. However, the concentration of sulfates in solution plays an important role in the solvation, diffusion and adsorption species at BDD surface, promoting parallel mechanisms. From the information provided by experimental measurements, the preferential mechanism on BDD surface at low or high overpotential regions was elucidated.

In this paper, thiosemicarbazones 4-N-cinnamoyl-thiosemicarbazone (CTSC), 4-N-(2'-methoxycinnamoyl)-thiosemicarbazone (MCTSC), and 4-N-(4'-hydroxy-3'-methoxybenzoyl)- thiosemicarbazone (HMBTSC) were solubilized in an oil-in-water (O/W) microemulsion system (ME_OCS), forming systems CTSC_ME_OCS, MCTSC_ME_OCS and HMBTSC_ME_OCS. The effectiveness of these systems in the process of inhibiting AISI 1020 carbon steel corrosion was evaluated in a saline solution (NaCl 0.5%), using a galvanostatic method. The tested thiosemicarbazones showed higher inhibitory effects (85.7% for CTSC_ME_OCS, 84.0% for MCTSC_ME_OCS, and 83.3% for HMBTSC_ME_OCS). The surfactant OCS (dissolved in H2O) and the ME_OCS system showed lower efficacies, with 71.0% for OCS and 74.0% for ME_OCS system.