Carbon nanofibre microfiltration membranes tailored by oxygen plasma for electrocatalytic wastewater treatment in cross-flow reactors

The engineering of electrocatalytic membrane reactors provides potential perspectives to integrate membrane separation with electrocatalytic technology for efficient removal of emerging organic pollutants from wastewater. Here, electro-responsive microfiltration carbon nanofibre (CNF) membranes were synthesized by electrospinning of poly(acrylonitrile) PAN and subsequent carbonization, followed by oxygen plasma treatment to induce their surface wettability and reactivity for electrocatalytic water treatment. The electrocatalytic performance of CNF membranes was fine-tuned via oxygen plasma treatment to yield reaction kinetic constants up to 29.6 × 10−3 and 15.6 × 10−3 min−1 against methylene blue (MB) and acetaminophen (ACP), respectively, which were 1.4–1.8 times higher than that exhibited by pristine CNF membranes. The water permeance across CNF membrane was gradually enhanced with increasing the plasma exposure time up to 5 min to exhibit 4.65 × 103 L m−2 h−1.bar−1, while the removal efficiency of MB and ACP was significantly improved to reach 99 and 91%, respectively during combined microfiltration and electrocatalytic reaction, which was 2.4–10.3 times higher than that achieved during microfiltration alone. The achieved performance of oxygen plasma treated CNF membranes was attributed to their enhanced wettability (water contact angle ∼24°) and raised electro-oxidation capacity (oxygen evolution potential ∼1.6 V) with introducing oxygen-containing groups on the membrane surface. This work offers an effective scalable fabrication methodology to engineer flexible and functional CNF membranes with excellent electrocatalytic performance towards cost-effective water treatment.