Transition metal-loaded granular activated carbon as efficient three-dimensional electrode for humic acid removal

Three-dimensional (3D) electrochemical treatment of organic wastewater has gained enormous interest due to its merits such as high processing efficiency, low energy consumption and environmental friendliness. However, the stability and cost issues of electrode materials still limit their practical applications. In this study, granular activated carbon (GAC) supported metal (Sn, Fe, Mn and Co) composites have been developed through an impregnation and pyrolysis method. Metal oxides and metal nitrides were formed on the GAC particle through high-temperature pyrolysis with the presence of cyanamide. The materials were applied for the removal of simulated and real humic acid (HA) wastewater, the Sn loaded GAC composite displays exceptionally high performance for electrocatalytic HA removal, achieving a removal rate of 98.4 % for simulated HA wastewater in 90 min and a similar removal rate (98.9 %) for real HA wastewater in 120 min. Further, the material demonstrated outstanding cyclic stability in simulated HA wastewater, the removal efficiency only slightly dropped from 98.2 % to 94.2 % after 14 cycles. The high removal efficiency of the metal-loaded GAC (GAC/M) is likely due to the transition metal bringing abundant catalytic sites and enhanced charge transfer as well as the electro Fenton-like effect. These findings highlight the substantial potential of metal-loaded GAC 3D electrochemical systems for sustainable applications in wastewater treatment.