Cathodic periodate activation driven by photocatalytic fuel cell for ciprofloxacin degradation

Abstract

Periodate (PI) is a promising oxidant in advanced oxidation processes, and its effective and sustainable activation is crucial for generating reactive species. In this study, a photocatalytic fuel cell (PFC) was employed to achieve cathodic activation of PI for ciprofloxacin (CIP) degradation. Photogenerated electrons from the photoanode activated PI at cathode, generating reactive species responsible for pollutant oxidation. As a result, the PFC-PI system achieved efficient CIP removal, significantly outperforming the PFC-only and PI-only control systems, and simultaneously produced electrical power. Mechanistic investigation revealed a pH-dependent shift of oxidation pathways, where 1O₂ dominated at pH 6, whereas radical-driven pathways prevailed under pH 3. PI was effectively converted to IO₃- without forming iodinated byproducts, confirming a benign conversion route. The identification of transformation products, combined with the density functional theory calculations, confirmed the proposed reaction mechanism. Although several intermediates exhibited higher predicted toxicity, the toxicity test showed reduced acute toxicity toward Vibrio fischeri as well as the antibacterial activity. This work expands the application of photocatalytic fuel cells by enabling periodate activation, offering a promising platform for advanced oxidation of emerging contaminants.