Synthesis and electrochemical properties of porous carbon materials from sludge sources

Anaerobic digestion sludge technology is a green and efficient method of treating sludge. However, the presence of humic acid (HA) in sludge can inhibit methanogenic efficiency, and it is necessary to reduce its impact on biogas production by removal or pretreatment. HA, a graphene oxide material can be used to produce high-performance energy-storage materials. Thus, this study examined the sludge source of HA as a precursor, and different electrode materials were prepared by varying the reaction conditions. The structure and electrochemical properties of the electrode materials were analyzed. The results showed that the electrode material prepared using KOH as an activator at 700 °C exhibited optimal performance, with a high specific surface area (1480.53 m²·g⁻¹), pore volume (0.943 cm³·g⁻¹), specific capacitance (185.9 F·g⁻¹), and equivalent series resistance (0.73 Ω). The material maintained 97.8% of its specific capacitance after 1000 cycles at a current density of 1 A·g⁻¹ with benign cycle stability. This study confirmed that the production of HA as an electrode material at a low cost with good performance presents significant prospects.