Novel Fe-Ti nanoparticles synthesized in deep eutectic solvents for enhanced photo-electro-Fenton processes: Synergistic effects and environmental applications

Abstract

An innovative titanium-magnetite (Fe-Ti) catalyst was developed using a production strategy based on water-free solvents such as deep eutectic solvents (DES) for the removal of persistent pollutants. The prepared catalyst was applied in electro-Fenton and photo-electro-Fenton processes. To this end, a new cell design with electrodes based on conductive materials was developed using 3D printing in two different electrochemical cells configurations: vertical electrode configuration (VEC) and horizontal electrode configuration (HEC). The HEC showed good performance attaining a yield hydrogen peroxide production of 20 mg⋅L1 and being able to operate in electro-Fenton degradation batch assays for the removal of the drugs (Antipyrine and Lissamine Green B). Then, the heterogeneous bimetallic catalyst (BC-FeTi) was tested and compared with the monometallic Fe catalyst (MCFe). The results with both catalysts showed a synergistic effect combining electrochemical oxidation and Fenton reaction, promoting the best removal of the target pollutants. Subsequently, the contribution of UV radiation was evaluated with BC-FeTi, achieving that more than 80 % of both pollutants were removed in 80 min by the photo- Fenton process, confirming the high affinity of oxidizing free radicals for high molecular weight organic molecules. Finally, the simultaneous application of electro- and photo-oxidation (photo-electro-Fenton) significantly improved the removal of the target contaminants from the aqueous solution, achieving complete removal in 50 and 80 min for Lissamine Green B and Antipyrine, respectively. The stability and reusability of BC-FeTi and 3Dprinted electrodes were achieved in five successive working cycles, with negligible loss of activity compared to new catalysts, which achieved greater than 99 % removal after five consecutive runs. Leaching of iron and titanium from the catalyst evaluated throughout the cycles, was low, totalling 2.7 and 4.5 % at the end of the fifth cycle.