A New Technique for Carbon Layer Formation for Application in Capacitive Deionization

This paper presents a novel technique for producing a CDI electrode through a straightforward process of converting activated carbon powder into a functioning stack for application in desalination. The foundation for this new technique is implementing the carbon layer via a novel carbon-on-mesh (CM) structure. This work elaborates on the CM formation process through flocculated carbon and filtration using the mesh as the filter medium. Alum-induced sweep flocculation, from a starting pH of 4.1 resulted in a good distribution of the PTFE binder to the carbon, as indicated by electron microscopy, producing a CM layer of 300 µm carbon thickness. Three electrode assemblies were handcrafted to demonstrate repeatability, comprising N  = 20 cells. The stack's performance was measured at 0.13, 0.13, and 0.11 mmol/g adsorption capacity based on NaCl outlet concentration. The average salt adsorption rate (ASAR) performance was 0.74, 0.73 and 0.70 mg/g/min at 1.2 V (300 seconds adsorb and 300 seconds zero-volt desorb). These results align with other benchmark studies indicating that this technique is effective at recreating a carbon stack that has good electrosorption characteristics. This study demonstrates that a CDI stack can made using common laboratory reagents and equipment thus reducing the barrier to entry for the technology.