Electrosynthesis of ferrate solution using a novel pilot-scale reactor: Ferrate's efficacy in trifluralin degradation and products ecotoxicity evaluation

Due to the continuous depletion of freshwater resources, there is an urgent need to develop versatile and cost-effective approaches for water and wastewater treatment. Accordingly, this work has provided an excellent solution, first by providing a new semi-automated pilot-scale electrochemical setup for the production of sodium ferrate and second, by carefully evaluating the application of ferrate for the complete degradation of trifluoralline (TRF) as one of the most dangerous and widely used agricultural herbicides worldwide. This reactor was manufactured in a user-friendly way using cheap and readily available materials for ease of scale-up in the industry. Under optimal conditions including NaOH concentration of 14M, applied current density of 0.028A/cm2 and temperature of 25 °C, the produced sodium ferrate concentration was 12.7mM. In this work, the electrochemical behavior of TRF, was also studied using cyclic voltammetry technique and a new mechanism for its electrooxidation was proposed. After that, the produced ferrate was used as a multimodal green reagent for the successful degradation of TRF to H2O and CO2. Techniques such as COD analysis, UV/Vis spectroscopy, CV analysis, LC/MS-MS, nephrometry and IR spectroscopy were used to track TRF removal. These techniques accurately confirm TRF degradation. The results show that under optimal conditions, the use of ferrate solution degraded 97% of TRF in aqueous solution after 120minutes of reaction. Finally, based on QSARs, we evaluated the ecotoxicity of TRF degradation products and concluded that the final products have no harm to aquatic species.