Capacitive Deionization -- defining a class of desalination technologies

TL;DR

This paper defines capacitive deionization (CDI) as a class of water desalination technologies characterized by ion removal via electroadsorption, enabling standardized comparison and analysis of evolving methods within this framework.

Contribution

It establishes a clear classification for CDI technologies, including recent variants, facilitating consistent evaluation and comparison across different desalination methods.

Findings

CDI involves electrically driven ion removal and storage in electrodes.

Treating related methods as a single class allows standardized analysis.

Enables comparison of new desalination technologies within the CDI framework.

Abstract

Over the past decade, capacitive deionization (CDI) has realized a surge in attention in the field of water desalination and can now be considered as an important technology class, along with reverse osmosis and electrodialysis. While many of the recently developed technologies no longer use a mechanism that follows the strict definition of the term "capacitive", these methods nevertheless share many common elements that encourage treating them with similar metrics and analyses. Specifically, they all involve electrically driven removal of ions from a feed stream, storage in an electrode (i.e., ion electrosorption) and release, in charge/discharge cycles. Grouping all these methods in the technology class of CDI makes it possible to treat evolving new technologies in standardized terms and compare them to other technologies in the same class.