Development of capacitive deionisation electrodes: optimization of fabrication methods and composition
The objective of this research was to optimize the fabrication methods for and compositions of electrodes for the Membrane Capacitive Deionisation (MCDI) system. Two electrode fabrication methods were developed, namely a spray coating- and a casting method. The compositions of the electrodes were varied yielding a total of 14 different electrode in an attempt to optimize the fabrication methods and compositions of the electrodes. Three activated carbons were utilized in this study, TOB, YP50F and YP80F, these activated carbons have different surface areas and porosity therefore were affected different by the materials added in the ink. Carbon black and carbon nanotubes were used as conductivity additives to enhance the conductivity of the electrodes. Lastly a polymer binder was added to increase the mechanical integrity of the electrode, this polymer was typically PVDF. For some electrodes, PVDF was replaced with ion exchange polymers in an attempt to provide ion conductive properties to the electrodes. To establish the charge capacity of the electrodes Cyclic Voltammetry was used, BET analysis evaluated the surface area and porosity of the raw materials and fabricated electrodes. Scanning Electron Microscopy was used to verify surface morphology and uniformity. Ion adsorption capacity measurements were performed using a specially designed MCDI cell. The objectives of this study were achieved, the fabrication methods were optimized with the casting method producing superior electrodes. Apart from fulfilling the research objectives, the current research work generated significant scientific value by revealing how the production method impacts the electrode's surface area and electrode adsorption capacity.