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Download fileDevelopment and Characterization of Ultrafiltration TiO2 Magnéli Phase Reactive Electrochemical Membranes
journal contribution
posted on 02.02.2016, 00:00 authored by Lun Guo, Yin Jing, Brian P. ChaplinThis research focused on the synthesis,
characterization, and performance
testing of a novel Magnéli phase (TinO2n–1), n = 4 to 6, reactive electrochemical membrane (REM) for water treatment.
The REMs were synthesized from tubular asymmetric TiO2 ultrafiltration
membranes, and optimal reactivity was achieved for REMs composed of
high purity Ti4O7. Probe molecules were used
to assess outer-sphere charge transfer (Fe(CN)64–) and organic compound oxidation through both direct oxidation (oxalic
acid) and formation of OH• (coumarin, terephthalic
acid). High membrane fluxes (3208 L m–2 h–1 bar–1 (LMH bar–1)) were achieved
and resulted in a convection-enhanced rate constant for Fe(CN)64– oxidation of 1.4 × 10–4 m s–1, which is the highest reported in an electrochemical
flow-through reactor and approached the kinetic limit. The optimal
removal rate for oxalic acid was 401.5 ± 18.1 mmol h–1 m–2 at 793 LMH, with approximately 84% current
efficiency. Experiments indicate OH• were produced
only on the Ti4O7 REM and not on less reduced
phases (e.g., Ti6O11). REMs were also tested
for oxyanion separation. Approximately 67% removal of a 1 mM NO3– solution was achieved at 58 LMH, with
energy consumption of 0.22 kWh m–3. These results
demonstrate the extreme promise of REMs for water treatment applications.