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Capacitive deionization (CDI) is a technology to deionize water by applying an electrical potential difference over two porous carbon electrodes. Anions, ions with a negative charge, are removed from the water and are stored in the positively polarized electrode. Likewise, cations (positive charge) are stored in the cathode, which is the negatively polarized electrode. Today, CDI is mainly used for the desalination of brackish water, which is water with a low or moderate salt concentration (below 10 g/L). Other technologies for the deionization of water are, amongst others, distillation, reverse osmosis and electrodialysis. Compared to reverse osmosis and distillation, CDI is considered to be an energy-efficient technology for brackish water desalination.〔 This is mainly because CDI removes the salt ions from the water, while the other technologies extract the water from the salt solution.〔 Historically, CDI has been referred to as electrochemical demineralization, "electrosorb process for desalination of water", or electrosorption of salt ions. It also goes by the names of capacitive desalination, or in the commercial literature as "CapDI". == History == In 1960 the concept of electrochemical demineralization of water was reported by Blair and Murphy. In that study, it was assumed that ions were removed by electrochemical reactions with specific chemical groups on the carbon particles in the electrodes. In 1968 the commercial relevance and long term operation of CDI was demonstrated by Reid. In 1970 Johnson et al. introduced a theory for the CDI process called ‘potential modulated ion sorption’; the latter is today more commonly known as the Electric Double Layer (EDL) theory. From 1990 onward, CDI attracted more attention because of the development of new electrode materials, such as carbon aerogels or carbon nanotube electrodes. In 1996, Farmer et al. also introduced the term capacitive deionization and used the now commonly abbreviation “CDI” for the first time. In 2004, Membrane Capacitive Deionization was introduced in a patent of Andelman. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Capacitive deionization」の詳細全文を読む スポンサード リンク
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