Flow anodic oxidation: Towards high-efficiency removal of aqueous contaminants by adsorb e d hydroxyl radicals at 1.5 V vs SHE

Electrochemical advanced oxidation processes (EAOPs) have emerged as a promising water treatment alternative but major breakthroughs are still needed in order for EAOPs to be competitive with traditional treatment technologies in terms of energy cost. Most existing studies have been conducted at high potentials to generate the powerful hydroxyl radical oxidant (aqueous center dot OH). While adsorbed hydroxyl radicals (OH*) may form at a much lower energy cost, their possible utilization is limited due to the poor mass transfer of this highly reactive species on solid electrodes. In this report, we describe a novel flow anode system using 4-16 mu m Magneli phase titanium suboxide particles as the anode material which enables the generation of a high steady state center dot OH concentration (5.4 x 10(-12) mol m(-2)) at only 1.5 V (vs SHE) in a dilute electrolyte (5 mM KH2PO4). The energy cost of removal per order of selected water contaminants (tetracycline and orange II in this study) using the flow anode is 1.5-6.7 Wh m(-3), which is 1 - 4 orders of magnitude lower than that of existing techniques. The anode material used demonstrates great stability with the configuration readily scaled up. The results of this study provide new insight into a high efficiency, low cost water treatment technology for organic contaminant degradation. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study successfully demonstrated the generation of high steady state hydroxyl radical oxidant at low cost under low potential using Magneli phase titanium suboxide particles as the anode material. The flow anode system developed in this study showed high efficiency and low cost for water treatment, enabling degradation of organic contaminants.