Use of mesoporous conductive carbon black to enhance performance of activated carbon electrodes in capacitive deionization technology

Capacitive deionization (CDI) is a technology for removal of dissolved salts from water by electrosorption of ions onto oppositely charged electrodes. The electrodes are usually made from activated carbon due to its high surface area. This paper reports the use of low levels of mesoporous conductive carbon blacks (MCCB) containing high fraction of mesopore surface area to enhance the capacitance of powdered activated carbon (PAC) electrodes. Different grades of MCCB with mesopore surface area varying from 65 m2/g to 455 m2/g were used. The capacitance of powdered activated carbon electrode could be enhanced from 13.8 F/g to 45.0 F/g at a scan rate of 5 mV/s by replacing 10% of powdered activated carbon with MCCB. The process for making these electrodes does not require use of organic solvent. The capacitance of improved electrode was comparable to that of commercially available carbon aerogel and activated carbon cloth electrodes. The removal of dissolved ions from water using a pair of electrodes (each weighing 11 g) at 10 ml/min was 75% and recovery was ~ 55% at applied potential of 1.2 V. Activated carbon electrodes containing low levels of MCCB offer high potential for use in capacitive deionization technology.

Research Highlights
► Use of mesoporous conductive carbon black enhances capacitance of electrodes.
► A simple process for making powdered activated carbon electrodes is described.
► The electrode making process is aqueous-based and does not require use of solvent.
► Electrodes showed high capacitance of 45.0 F/g at a scan rate of 5 mV/s.
► PAC electrodes with low levels of MCCB can be ideal materials for CDI technology.