Antifouling ceramic membrane electrode modified by Magnéli Ti₄O₇ for electro-microfiltration of humic acid

A compact electro-microfiltration (EMF) module was designed for the treatment of humid acid (HA). In this module, an inner-layer modified Magnéli Ti₄O₇/Al₂O₃ tubular membrane was utilized as both the filtration media and the electrode. This study demonstrated that applying electric field could dramatically enhance the microfiltration (MF) performance. When the electric field was near the critical value of 81.2 V cm⁻¹ without adding electrolyte, a flux comparable to that of Milli-Q water filtration was attained. With 6 and 12 mg L⁻¹ total organic carbon (TOC) of HA in the feed solutions, the HA rejections in terms of UV₂₅₄ were 96.5 and 91.0%, TOC removals were 88.3 and 86.7% respectively, much higher than those using MF alone without electric field (<5%). At 75 V cm⁻¹, the energy consumption is around 0.21 kW h per m³ of permeate per hour, which is over 50% lower than that of corresponding ultrafiltration when similar permeate volume and HA rejection are achieved. It was also found that HA rejection increased with higher pH at the same feed conductivity of around 60 μS cm⁻¹. High HA rejection of 97.8% in terms of UV₂₅₄ was obtained at the feed pH of 8.3 and 75 V cm⁻¹.