Carbon-Based Electric Double Layer Capacitors for Water Desalination

Abstract

In capacitive deionization (CDI), salt water is passed through two polarized electrodes, whereby salt is adsorbed onto the electrode surface and removed from the water stream. This approach has received renewed interest for water desalination due to the development of new high-surface area, carbon-based nanomaterials. However, there is limited understanding as to how electrode geometry, surface properties, and capacitance affect ion capture. In this work, we experimentally investigated various standard carbon-based electrode materials, including activated carbon and carbon cloths, as well as microfabricated silicon structures for CDI. Electrochemical characterization through cyclic voltammetry was used to determine the electrochemical properties of each material. The capacitance values of the carbon materials tested were 40 F/g for 2000 m 2 /g carbon cloth, 32 F/g for 1000 m 2 /g carbon cloth, and 25 F/g for activated carbon. In addition, we constructed two iterations of flow test channels to perform parametric studies on ion capture. The first flow cell utilized a commercial conductivity probe to measure salt concentration after charging the electrodes without flow. We showed that the ion capture on both the carbon cloth and activated carbon electrodes were proportional to the applied voltage, however two orders of magnitude smaller than what is expected from the electrode charge. We addressed a significant experimental limitation in the second flow cell by integrating conductivity sensors into the flow channel to measure effluent salt concentration during electrode charging. We found that the salt adsorption increased from 33.1 pmol/g in the first flow cell to 63.5 pmol/g in the redesigned flow for an applied potential of 1.2 V. Future directions will focus on controlling electrode geometry and chemistry to help elucidate transport mechanisms and provide insight into the design of optimal materials for capacitive deionization.

Sorting Short Fragments of Single-Stranded DNA with an Evolving Electric Double Layer

“…Since the hydrated ion size is about 0.7 nm for sodium, 38 it’s easy to check the saturation limit value for surface potential is about −160mV. Whereas the standard Poisson-Boltzmann theory ignores the steric effect, the fact that fitted surface potential below the saturation limit value somewhat indicates the validity of its application.…”

Perancangan Sistem Desalinasi Air Laut Menggunakan Multi Sel Elektroda Capacitive Deionization (CDI) Berbasis Karbon Aktif Tempurung Kemiri

“…Selain itu, aplikasi kapasitor electric double layer (EDL) berbahan dasar karbon aktif dan karbon cloth juga dikembangkan untuk desalinasi air laut [8]. Plat elektroda CDI dengan bahan karbon aktif yang berasal dari tempurung kelapa dengan proses sheet casting menggunakan metode doctor blade juga telah diteliti.…”

Pemanfaatan Karbon Aktif Dari Bambu Sebagai Elektroda Superkapasitor

“…Salah satu faktor yang mempengaruhi tingkat keefektifan superkapasitor adalah penggunaan bahan elektroda. Karbon aktif adalah salah satu jenis bahan yang secara luas telah digunakan sebagai bahan elektroda untuk superkapasitor karena memiliki luas permukaan spesifik yang tinggi, ketahanan kimia, konduktivitas listrik yang baik dan harga yang terjangkau (Babel dan Jurewicz 2004;Fellman 2010;Aripin et al 2010). Bambu dapat dijadikan sumber bahan baku dalam pembuatan karbon aktif.…”