Capacitive, deionization with carbon aerogel electrodes: Carbonate, sulfate, and phosphate

Abstract

This is a preprint of a papcr inknded for publication in a journal or proceedings. Since changes may bc made before publication, this preprint is ma& available with the undcrstanding that it will not bc citcd or reproduced without the permission of the author. DISCLAIMERThis document was prepared as an m u n t of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any wmranty, express or implied, or assumes any l g a l liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or prdisclosed, or represents that its use would not infringe privately owned rights. ABSTRACTCapacitive deionization with carbon aerogel electrodes is an efficient and economical new process for removing salt and impurities from water. Carbon aerogel is a material that enables the successful purification of water because of its high surface area, optimum pore size, and low electrical resistivity. The electrodes are maintained at a potential difference of about one volt; ions are removed from the water by the imposed electrostatic field and retained on the electrode surface until the polarity is reversed. The capacitive deionization of water with a stack of carbon aerogel electrodes has been successfully demonstrated. The overall process offers advantages when compared to conventional water-purification methods, requiring neither pumps, membranes, distillation columns, nor thermal heaters. Consequently, the overall process is both robust and energy efficient. The current state of technology development, commercialization, and potential applications of this process are reviewed.

Evaluation of Carbon Aerogel Manufacturing Process in Order to Desalination of Saline and Brackish Water in Laboratory Scale

“…In these studies, by increasing the input concentration, the absorption rate of carbon aerogel electrodes were increased, as well [23].…”

“…Because the cations and anions fall into a trap in the electrical double layers and are released in the stage of recycling by reversing the flow for 15 to 45 minutes. Subsequently, the salt concentrations are increased by creating an electric current and passing time and gradually increases during regeneration [12,23]. Environmental pH creates a severe effect of many chemical reactions.…”

Desalination with carbon aerogel electrodes. Revision 1

“…More recently, an electrochemical process for the capacitive deionization (CDI) of water with stacks of carbon aemgel composite (CAC) electrodes has been developed by Lawrence Liverrnore National Laboratory [16][17][18][19][20][21][22][23][24]. An aqueous solution of NaCl, NalC03, Na2SOA or another salt is passed between numerous pairs of carbon aerogel electrodes, each having a very high BET.…”

“…In the specific case of carbon aerogel C.DI, LLNL. has investigated a broad range of cell voltages [16][17][18][19][20][21][22][23][24]. The best performance (salt removal) was achieved at -1.2-1.3 V, though operation at 0.6 V was found to be possible.…”

“…' [18] Clearly, the value of CP will have to be greater than zero, a requirement that places constraints on CF, R,~,~, &~O~elad~aeroge~In Equations 1.7 and 18, the factor 2~.e,ogel(l-P.,ro&/Pmr~O# assumes that the CAC sheets used to construct anodes and cathodes have identical thicknesses. Since the process may be anion limited [8], one might be able to use much thher CAC sheets for the cathodes than for the anodes, perhaps with &,~~, -0.…”