Zeolitic imidazolate framework-8 modified active carbon fiber as an efficient cathode in electro-Fenton for tetracycline degradation

Abstract

In this work, the active carbon fibers (ACFs) was modified by zeolitic imidazolate framework-8 (ZIF-8) to prepare a novel modified electrode as cathode. The effect of different amount of ZIF-8 modified ACFs (0–0.30 g) on H2O2 production and electric energy consumption (EEC) were investigated and the optimal ZIF-8 amount was 0.15 g. Characterized by linear sweeping voltammetry (LSV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), contact angle, and X-ray photoelectron spectroscopy (XPS) after modification were observed considerably changed. Some nanoparticles and oxygen-contained functional groups appeared on the ZIF-8/ACF cathode surface, which significantly enhanced the hydrophilic property and the electrochemical performance. It was observed that H2O2 production with 0.15 g-ZIF-8/ACF as cathode (1545.1 mg L−1) was much larger than with raw ACF as cathode (64.1 mg L−1). Meanwhile, H2O2 production could also achieve a balance in a high state of H2O2 production (around 1500 mg L−1) with low EEC (<35.0 kWh kg−1) in consecutive 5 runs. Moreover, 50 mg L−1 tetracycline could be completely removed within 20 min in the electro-Fenton (EF) system with 0.15 g-ZIF-8/ACF as cathode and the TOC removal could achieve 82.6% which was also much higher with raw ACF as cathode (15.5%). According to the ESR tests also indicating much more OH radicals could be generated in the EF system with 0.15 g-ZIF-8/ACF. Therefore, EF system with ZIF-8/ACF cathode is a good alternative process for pollutant removal.