Photoelectrocatalytic degradation of pollutants (bisphenol-A, sulfamerazine, and 2,4-D) using H2O2 electrogenerated in carbonaceous matrices obtained from sustainable sources

Abstract

Currently, the development of clean and efficient technologies for the remediation of toxic industrial waste is of vital importance. In this context, the in-situ generation of hydrogen peroxide (H2O2) by carbonaceous gas diffusion electrodes (EDGs) and the subsequent creation of hydroxyl radicals through the homogeneous photoelectro-Fenton process emerges as an efficient way for the treatment of effluents containing emerging organic pollutants, such as antibiotics, pesticides, and endocrine disruptors. Aiming at the efficient and sustainable generation of H2O2, the development of carbon gel EDGs synthesized from renewable carbon sources (such as lignin, tannin, and cellulose) is a highly relevant tactic to improve the environmental and economic factors involved in the photoelectro-Fenton process. Furthermore, the association of this method with the heterogeneous photocatalysis process emerges as a promising strategy for optimizing the remediation efficiency of toxic effluents, due to the increase of hydroxyl radicals in the reaction medium. Regarding heterogeneous photocatalysis, the optimization of the photodegradation process can be achieved by the development of photocatalysts based on the formation of S-scheme heterojunctions between semiconductors, since this strategy leads to the efficient transport of photogenerated charges and the consequent intensification of the active radical's generation. Therefore, this project proposes the association of the photoelectro-Fenton process employing sustainable carbonaceous EDGs and heterogeneous photocatalysis using TiO2/KNbO3/g-C3N4 photocatalysts for the degradation of the model pollutants bisphenol-A, sulfamerazine, and 2,4-dichlorophenoxyacetic acid under ultraviolet and solar irradiation, in benchtop batch reactor and pilot batch reactor. The proposed S-scheme heterojunction between the 3 semiconductors aims to facilitate charge transport and increase photocatalytic activity under visible radiation. The efficiency of the proposed degradation process will be evaluated using the techniques of spectrophotometry, high-performance liquid chromatography, total organic carbon content, and mass spectrometry.