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

- A compact EMF system is designed for membranes with inner filtration layer.
- The inner membrane layer serves as both the electrode and the filtration media.
- HA rejections in terms of UV254 of over 97% and TOC of over 85% are achieved.
- The system could replace UF due to comparable HA removal and much higher flux.
- PH is found to have an observable impact on both permeate quality and quantity.

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.

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