Advanced Electrochemical Processes for the Elimination of Pharmaceutical Compounds in Contaminated Waters

Abstract

Electrochemical systems have often been investigated for the removal and degradation of pharmaceuticals in water, mainly focusing on their electrooxidation kinetics and transformation pathways and sometimes relying on sophisticated high-resolution mass spectrometry (HRMS) analysis. Most of these studies are based on ideal experimental designs of high electrolyte conductivity and high contaminant concentration, resulting in outputs that can hardly be extrapolated to a real case scenario. This chapter discusses a limited number of studies in which the performance of electrochemical systems in removing and degrading pharmaceutical residues was evaluated using real waste streams. The main mechanisms of electrochemical oxidation of pharmaceuticals are explained, with a particular emphasis on the recently reported participation of strong oxidant species, sulfate radicals, in electrooxidation of organic contaminants. Finally, as electrode and reactor design evolves toward three-dimensional geometries with reduced mass transfer limitations, significant attention has been paid to the progress made using flow-through, porous electrode materials for the electrooxidation of pharmaceuticals. Novel, electrocatalytically active, stable membrane and foam/sponge-type electrodes are thoroughly discussed as such materials represent an essential enabler of a wider-scale implementation of electrochemical treatment systems and their integration into water and wastewater treatment infrastructure.