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English, Joseph

University of British Columbia

The development of effective yet inexpensive technologies for wastewater treatment is critical to the safeguarding of water resources and the delivery of clean water for sanitation and drinking. Electrochemical technologies are of growing relevance in an increasingly decentralized, distributed, and electrified system. High oxidation potential (HOP) materials, so called for their ability to generate efficacious conditions for water treatment, are critical to their development. One such HOP, Magnéli phase titanium oxides (MPTOs), are being utilized to advance this domain; however, issues of its stability constrain the applicability of devices that employ them. Doping influences many physicochemical properties of MPTOs relevant to their use as electrode materials. The rational selection of dopants for MPTOs is explored using Hume-Rothery rules for solid substitutional solutions, selecting transition metals vanadium, chromium, and iron as potentially highly soluble dopants. Their thermal stability is investigated using thermogravimetric analysis (TGA) in air and a model for their thermal oxidation is developed from kinetic data. Electrochemical accelerated life testing (ALT) is conducted with doped MPTO electrodes and their influence on the time to failure is evaluated. These tests establish that vanadium doping provides a significant improvement to the stability of MPTOs in thermally and electrochemically oxidizing conditions. Porous transport layers (PTLs) of vanadium-doped MPTOs are prepared and incorporated into a compact electrolyzer, which is used to treat industrial wastewater. Vanadium-doped MPTO PTLs provide a significant improvement in performance over pristine materials in terms of volumetric energy consumption. Furthermore, the compact electrolyzer design places this approach in the top quartile of this class of electrochemical devices, which is attributed to the reduced interelectrode distance.

Text

2023-07-20

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85282

Chemical and Biological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/