EES Blog

Researchers, led by Dr. Volker Presser in Germany, present a methodology to directly predict the desalination performance of carbon-based electrodes for capacitive deionization (CDI), an important first step towards directed CDI design.

Carbon-based electrodes offer an energy-efficient water desalination technology that involves removal of ions from water by electrosorption in charged porous carbon electrodes. The family of carbon materials ranging from activated carbons, carbon nanotubes, exfoliated grapheme electrodes to templated carbons and carbide-derived carbons have been extensively studied for desalination by CDI. To achieve optimal performance, components of the CDI system need to be tuned to achieve both high salt electrosorption capacity and fast kinetics, simultaneously. Therefore, tools to predict the performance of a certain carbon material and CDI design are essential for device design.

Given the inherent non-linearity of desalination by porous carbons, Porada et al. in their paper, Direct Prediction of the Desalination Performance
of Porous Carbon Electrodes for Capacitive Deionization, follow a two-prong approach: i) predict the desalination performance of a carbon material based on its pore size distribution and ii) use a two-dimensional porous electrode CDI transport model to predict the actual salt electrosorption kinetics. The authors have convincingly demonstrated that there is no direct relationship between salt electrosorption capacity and typically cited pore metrics and that the salt electrosorption capacity can be predicted by analysis of the pore size distribution and the pore volume correlated with incremental pore size ranges.

Despite the complexity of CDI, their work has shown the feasibility of predicting performance of different carbon-based materials in a passionately debated field. Looking ahead, the rational device design of carbon electrodes is certainly on the cards.  This paper is a must-read for anyone working in the field of carbon materials!

Read the paper here:

Direct Prediction of the Desalination Performance of Porous Carbon Electrodes for Capacitive Deionization
Slawomir Porada, Lars Borchardt, Martin Oschatz, Marek Bryjak, Jennifer Atchison, Karel J. Keesman, Stefan Kaskel, Maarten Biesheuvel and Volker Presser
DOI: 10.1039/C3EE42209G

By Prineha Narang