Sustainable bioelectric activation of periodate for highly efficient micropollutant abatement

Abstract

The periodate (PI)-based advanced oxidation process is valued for environmental remediation, but current activation methods involve high costs, secondary contamination risks, and limited applicability due to external energy inputs (e.g., UV), catalyst incorporation (e.g., Fe²⁺), or environmental modifications (e.g., freezing). In this work, novel bioelectric activation of PI using the electrons generated by electroactive bacteria was developed and investigated for rapid removal of carbamazepine (CBZ), achieving 100 %, 100 %, and 76 % removal efficiency for 4.22 µM of CBZ in 20 min at pH 2, 120 min at pH 6.4, and HRT of 30 min at pH 8.5, respectively, with a 1 mM PI dose and without an input voltage. It was deduced that electrons derived from bacteria could directly activate PI using Ti mesh electrodes and generate •IO₃ via single electron transfer under strongly acidic conditions (e.g., pH 2). Nevertheless, under weak alkaline conditions (e.g., pH 8.5), biogenic electrons indirectly activated PI by generating OH^-via 4e^-reduction at the Ti mesh cathode, resulting in the formation of •O₂^- and ¹O₂. In addition to the metal cathode, a carbon-based cathode finely modulates the 2e^-reduction, yielding H₂O₂ and activating PI to mainly form •OH. Moreover, primarily non-toxic IO₃^- was produced during treatment, while no detectable reactive iodine species (HOI, I₂, and I₃^-) were observed. Furthermore, the bioelectric activation of PI demonstrated its capability to remove various micropollutants present in secondary-treated municipal wastewater, showcasing its broad-spectrum degradation ability. This study introduces a novel, cost-effective, and environmentally friendly PI activation technique with promising applicability for micropollutant elimination in water treatment.

Keywords: Advanced oxidation process; Bioelectric activation; Biogenic electrons; Micropollutants; Periodate.