Activated carbon from the waste water purifier for supercapacitor application

Activated carbon has been synthesized from the waste filter carbon in household water purifier. The original waste filter carbon (OFC) gives poor specific capacitance. However, the activated carbon SA-900-4 (OFC was heat treated at 900 degrees C to get SC-900, then SC-900 was activated by KOH with mass ratio of SC-900:KOH = 1:4 at 800 degrees C) shows great electrochemical performance. The SA-900-4 has a specific capacitance of 122.8 F g(-1) at current density of 1 A g(-1) in 1 M H2SO4 electrolyte. Furthermore, the specific capacitance of SA-900-4 is 93.8 F g(-1) at 10 A g(-1) and 78.1 F g(-1) at 20 A g(-1), nearly 76 and 63.6% of the value at 1 A g(-1), respectively, indicating good rate capacity of this activated carbon. In addition, the highest energy densities of 15.4 Wh kg(-1) in 1 M H2SO4 and 32.9 Wh kg(-1) in 1 M Na2SO4 were obtained respectively for the two-electrode supercapacitors based on SA-900-4. It is demonstrated that the waste filter carbon has the potential to be recycled as electrode material for electrochemical energy storage.