Development and Evaluation of an Electrode for the Capacitive Deionization Unit

Abstract

The existing conventional technologies like Reverse Osmosis, EDI(Electro Deionization), membrane filtration and Ultra Violet filtration offer solutions for drinking water, but various factors like capital and operational cost, ease of operation, maintenance and fouling had been the considerable driving factors to judge the techno-economic paradigm while making a technology selection.Also, the increasing demand for augmenting the safe drinking water calls for novel and sustainable breakthrough technologies.The novel and sustainable technology like Capacitive deionization (CDI) could be a potential alternative which works on electrophoretic phenomenon to provide low TDS (Total Dissolved Solids) drinking water.When water passes between a pair of carbon aerogel electrodes, ionic species are held at the charged electrode surfaces and are removed from the solution during the charging the cycle.After the electrodes become saturated with salts or impurities, the electrodes are regenerated by electrical discharge or polarity reversal, allowing the captured ions to be released into a relatively small purge stream.Thus, CDI can be used to deionize or purify water.An effort is also made to study, evaluate and compare conventional RO technology with Existing CDI technology.Batch ion absorption studies on the newly developed electrodes recorded efficiency with ion removal of 140 ppt using 5 pairs of electrodes (32m 2 area) and the SEM images of the developed electrodes indicated good porosity which in turn illustrates the potential absorption capacity of the developed electrodes.The main factors to be considered while developing an ideal electrode are some of the properties like BET(, electrical conductivity, capacitance, mechanical strength.Correlation studies on the comparison with RO and evaluation of the developed electrodes of the CDI were carried out.