Electroactive adsorbent composites of porous graphite carbon/carbon nanotube for highly efficient organic dye removal

The highest total organic carbon (TOC) and color removal efficiency of Acid Orange 7 (0.1 mM initial concentration) on graphite carbon/carbon nanotubes electrodes (KS44/CNT) reached more than 98% in three hours of Electro-Fenton (EF) treatment under optimal conditions (pH=3 and I=20 mA), compared to carbon graphite electrode developed without carbon nanotubes (KS44-0). The apparent kinetic constants of degradation were 0.17 and 0.12 min−1 for the KS44-(20)/CNT and KS44-0, respectively. The long-term stability and system durability were attributed to the graphite carbon/CNT electrodes due to continuous operating treatment that allowed processing efficiency and reusability without any decrease of the catalytic activity in time after five cycles of use. Regardless of the medium, superior decolorization and TOC removal efficiency were obtained for electrodes (KS44-(20)/CNT) containing 20 wt% of ferrocene powder as catalyst for CNTs’ growth and iron nanoparticle establishment. Furthermore, the presence of CNTs and iron particles as precursors enhanced drastically the electrochemical and physical properties of the electrode synthesized in a one-step process. The results confirmed that carbon electrodes behave as multifunctional materials acting both as adsorbent and active cathode in the electro-Fenton process for the destruction and total mineralization of Acid Orange 7 (AO7) as a model for organic contaminated wastewater.