A Covalently Integrated Reduced Graphene Oxide–Ion‐Exchange Resin Electrode for Efficient Capacitive Deionization

Abstract

terms of equipment and energy consumption. [6,8-11] Capacitive deionization (CDI) is an emerging technology which involves adsorption and desorption of ions on the electrode surface by application of low potential difference (≈1.2-1.8 V) across a pair of porous carbon electrodes, thereby making it both energy and cost-efficient compared to other existing desalination methods. When a flowing water stream is passed across a CDI system, cations and anions move toward oppositely charged electrodes and get adsorbed on them, thereby generating deionized and 'drinkable' water, starting from brackish water. Subsequently, adsorbed ions can be removed from the electrode by reversing the polarity, thereby regenerating the electrode surface, ready for reuse for next adsorption cycle. [5] Thus, clean water can be produced continuously by repeating the adsorption and desorption cycles. CDI is a cost-effective, point-of-use method with a high theoretical desalination efficiency. [5] However, its practical applications for desalination are yet to be recognized at a large scale, and research is being carried out to synthesize new materials with improved adsorption capacities. [5,12-14] Related technologies such as Faradaic deionization and the use of different 2D materials in CDI are also explored intensely. [15-17] Various carbonaceous materials and their composites are being used as CDI electrodes because of their high salt adsorption capacities in the range of several mg g −1. [18-25] Graphene, and graphene-derivatized materials, such as, graphene-like nanoflakes, [26] activated carbon, [27] activated carbon nanofiber (ACF), [28] reduced graphene oxide (rGO), [27,29] carbon nanotubes (CNT), [29] graphene-CNT composites, [29,30] rGO-ACF, [28] 3D macroporous graphene architectures, [31] sponge-templated graphene, [14] graphene-Fe 3 O 4 , [32] graphene chitosan-Mn 3 O 4 , [33] rGO-activated carbon composites, [27] and functionalized graphene nanocomposite, [34] have been used as CDI electrodes. The adsorption capacities of graphenic composites, such as graphene/carbon nanotube, CO 2 activated rGO, sulfonic functional graphite nanosheets, SO 3 H/NH 2 graphene/activated carbon, MgAl-Ox/G nanohybrids, 3D-graphene architecture, and graphene sponge measured were 1

Selective and Practical Graphene-Based Arsenite Sensor at 10 ppb

“…Electrode Fabrication. The complete fabrication process of ERGO electrodes comprised the synthesis of GO by modified Hummer's method, 31 pretreatment of Au strips with sodium 2mercaptoethanesulfonate (MESA), coating of GO on Au strip by the drop cast method, and finally electroreduction of the GO film. Each of these steps is described in detail in the Supporting Information.…”

Aminoclay‐Graphene Oxide Composite for Thin‐Film Composite Reverse Osmosis Membranes with Unprecedented Water Flux and Fouling Resistance

“…Preparation of Graphene Oxide: Graphene oxide (GO) was synthesized from graphite powder using a modified Hummer's method. [51,52] Graphite powder was oxidized using concentrated sulphuric acid (H 2 SO 4 ), potassium persulphate (K 2 S 2 O 8 ), and phosphorus pentoxide (P 2 O 5 ) as oxidizing agents. The resulting dark blue mixture was cooled to room temperature.…”

Industrial Utilization of Capacitive Deionization Technology for the Removal of Fluoride and Toxic Metal Ions (As3+/5+ and Pb2+)

“…In this context, capacitive deionization (CDI) is emerging as an alternative desalination technology as it is capable of desalination of ionic and polarizable pollutants from brackish water at an affordable cost. [ 28 ] CDI works on the principle of electroadsorption of ions on porous carbon electrodes when a small potential difference (0.8–2.0 V) is applied across them. [ 29 ] A CDI cell consists of a pair of porous electrodes (mainly made of carbon), separated by a nonconducting membrane called as separator.…”