http://www.cdi-electrosorption.org/wp-content/uploads/2014/06/Porada-et-al.-2013-Review-on-the-Science-and-Technology-of-Water-Desalination-by-Capacitive-Deionization.pdf

Review on the science and technology of water desalination by capacitive deionization

The Maxwell-Stefan approach to mass transfer

Adsorption of organic molecules from aqueous solutions on carbon materials

Adsorption of phenolic compounds by activated carbon—a critical review

Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charged electrodes, commonly composed of highly porous carbon materials. The CDI community has grown exponentially over the past decade, driving tremendous advances via new cell architectures and system designs, the implementation of ion exchange membranes, and alternative concepts such as flowable carbon electrodes and hybrid systems employing a Faradaic (battery) electrode. Also, vast improvements have been made towards unraveling the complex processes inherent to interfacial electrochemistry, including the modelling of kinetic and equilibrium aspects of the desalination process. In our perspective, we critically review and evaluate the current state-of-the-art of CDI technology and provide definitions and performance metric nomenclature in an effort to unify the fast-growing CDI community. We also provide an outlook on the emerging trends in CDI and propose future research and development directions.

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Water desalination via capacitive deionization : What is it and what can we expect from it?

A method is presented to estimate the diffusivities of electrolytes in concentrated multicomponent systems. The method is based on the Stefan-Maxwell flux equations. Explicit expressions have been developed for the phenomenological transport coefficients. These expressions incorporate the effects of solvation, viscosity, and ionic interactions. It has been shown that multicomponent diffusion behavior can be related to corresponding single-electrolyte and tracer diffusion cases. Thus, solvation effects are estimated from single-electrolyte data, and ion-ion interaction effects are obtained from tracer diffusion studies. The method has been tested for the ternary system NaCl-KCl, at concentrations of up to 3.0 M, and for corresponding single-electrolyte and tracer diffusion cases at concentrations of up to 4.0 M. In general, the method predicts phenomenological coefficient values within 1.5% of the experimental values for univalent systems.

Multicomponent diffusion in concentrated electrolyte solutions : effect of solvation.

Application of the shrinking core model for predicting protein adsorption.

Non-porous silica fibers, 1 μm in diameter and up to 100 μm long, have been coated by dispersion in silica sols in order to increase their specific surface area and improve the adsorption capacity for chromatographic bioseparations. Both acid- and base-catalyzed sols were investigated. Coatings with an acid-catalyzed sol resulted in a hundredfold increase in the specific surface area of the fiber. However, formation of fiber flocks by this method caused problems in packing chromatographic columns with these fibers. By contrast, coatings by dispersion in base-catalyzed sols resulted in looser flocks that facilitated column packing. Various sol compositions and fiber mass concentrations in base-catalyzed sols increased the specific surface area of the fibers by up to 30 times. Washing with acetone or ethanol reduced the specific surface area of the coated fibers by about 80%.

Surface area enhancement of silica fibers by sol-gel processes

Characterization of ionic diffusivities in ion-exchange resins.

A new class of adsorbents for direct capture of mercury from warm-gases has been developed. In these adsorbents, a dicarboxylic acid (DCA) is dissolved in a selective ionic liquid (IL) layer; the DCA + IL solution is coated on a mesoporous support. Mercury is absorbed by the IL and reacts with the DCA to form a halatopolymer, immobilizing the captured mercury. A prototype adsorbent was prepared by coating the IL [bmim]Cl and azelaic acid on mesoporous silica. Thermogravimetric analysis indicates that the adsorbent is thermally stable at the target operating temperature. Fixed-bed adsorption tests of elemental mercury capture from nitrogen at 160°C show that this adsorbent can capture 44 mg Hg0/g adsorbant. Leaching tests indicate that the captured mercury is held tightly by the adsorbent. The high mercury capacity and high adsorption temperature suggest that the prototype adsorbent is competitive with modified carbons currently used in integrated gasification combined cycle applications.

Neville G. Pinto

Papers

Multicomponent diffusion in concentrated electrolyte solutions : effect of solvation.

Application of the shrinking core model for predicting protein adsorption.

Surface area enhancement of silica fibers by sol-gel processes

Characterization of ionic diffusivities in ion-exchange resins.

New adsorbents for direct warm-gas capture of mercury