Modifying graphite felt cathode by HNO3 or KOH to improve the degradation efficiency of electro-Fenton for landfill leachate.

Abstract

Based on graphite felt (GF), the cathode of an electro-Fenton (EF) system was modified by HNO3 and KOH respectively to improve the degradation efficiency for actual landfill leachate. The results of Fourier transform infrared spectroscopy (FTIR) spectra, Boehm titration experiments, contact angle, scanning electron microscopy (SEM) and adsorption experiments illustrated that the surface of the modified GFs had more oxygen-containing functional (OG) groups, and possessed better hydrophilicity and larger specific surface area. In 180 min H2O2 electrogeneration experiments, the cumulative amount of H2O2 produced by unmodified GF (GF-0), HNO3 modified GF (GF-1) and KOH modified GF (GF-2) was 526 mg/L, 891 mg/L and 823 mg/L respectively. In 180 min EF reaction, the removal rate of chemical oxygen demand (COD) in GF-0, GF-1 and GF-2 EF systems was 31.88%, 60.65% and 52.08% respectively; the removal rate of NH4 +-N in GF-0, GF-1 and GF-2 EF systems was 43.37%, 98.10% and 94.81% respectively. In addition, both the performance of GF-1 and GF-2 for Fe2+ regeneration was greatly enhanced, and GF-1 was superior to GF-2. The degradation efficiency for landfill leachate was enhanced obviously by employing the modified EF system, suggesting that the two modified cathodes have great potential in practical production.