Applied Energy, Vol.208, 25-36, 2017
Supercapacitive microbial desalination cells: New class of power generating devices for reduction of salinity content
In this work, the electrodes of a microbial desalination cell (MDC) are investigated as the positive and negative electrodes of an internal supercapacitor. The resulting system has been named a supercapacitive microbial desalination cell (SC-MDC). The electrodes are self-polarized by the red-ox reactions and therefore the anode acts as a negative electrode and the cathode as a positive electrode of the internal supercapacitor. In order to overcome cathodic losses, an additional capacitive electrode (AdE) was added and short-circuited with the SC-MDC cathode (SC-MDC-AdE). A total of 7600 discharge/self-recharge cycles (equivalent to 44 h of operation) of SC-MDC-AdE with a desalination chamber filled with an aqueous solution of 30 g L-1 NaCl are reported. The same reactor system was operated with real seawater collected from Pacific Ocean for 88 h (15,100 cycles). Maximum power generated was 1.63 +/- 0.04 W M-2 for SC-MDC and 3.01 +/- 0.01 W m(-2) for SC-MDC-AdE. Solution conductivity in the desalination reactor decreased by similar to 50% after 23 h and by more than 60% after 44 h. There was no observable change in the pH during cell operation. Power/current pulses were generated without an external power supply.
Keywords:Supercapacitive Microbial Desalination Cell (SC-MDC);Additional Electrode (AdE);Power/current pulses;High power generation;Transport phenomena