Dual-channel membrane capacitive deionization based on asymmetric ion adsorption for continuous water desalination

Electrochemical water desalination has been a major research area since the 1960s with the development of capacitive deionization technique. For the latter, its modus operandi lies in temporary salt ion adsorption when a simple potential difference (1.0–1.4 V) of about 1.2 V is supplied to the system to temporarily create an electric field that drives the ions to their different polarized poles and subsequently desorb these solvated ions when potential is switched off. Capacitive deionization targets/extracts the solutes instead of the solvent and thus consumes less energy and is highly effective for brackish water. This paper reviews Capacitive Deionization (mechanism of operation, sustainability, optimization processes, and shortcomings) with extension to its counterparts (Membrane Capacitive Deionization and Flow Capacitive Deionization).

Download Full-text

Diffusion-bonded CNT carpets for fundamental CDI studies

MRS Proceedings ◽

10.1557/opl.2012.707 ◽

2012 ◽

Vol 1407 ◽

Author(s):

R. Enright ◽

R. Mitchell ◽

H. Mutha ◽

C. Lv ◽

M. Christiansen ◽

...

Keyword(s):

Cyclic Voltammetry ◽

Carbon Nanotube ◽

Pore Structure ◽

Electrochemical Capacitor ◽

Water Desalination ◽

Carbon Electrodes ◽

Aqueous Electrolytes ◽

Ion Adsorption ◽

Capacitive Deionization ◽

Multi Scale

ABSTRACTUncertainty about future energy and water supplies suggests a pressing need to develop efficient technologies for water desalination. Capacitive deionization (CDI), a method that captures ions in the electrical double layer (EDL) of an electrochemical capacitor, is a promising technology that can potentially fulfill those requirements. Similar to supercapacitors, ideal CDI electrodes should have a large electrolyte-accessible specific surface area available for ion adsorption with rapid charging/discharging characteristics. Unlike supercapacitors, CDI electrodes are required to operate in aqueous electrolytes with low ionic concentrations in a non-linear charging regime. To explore this practically and theoretically important regime, we developed robust, electrochemically-compatible carbon nanotube (CNT) carpet electrodes that posses a well-defined and uniform pore structure that is more readily analyzed in comparison to the random and multi-scale pore structure of typical carbon electrodes. The fabricated electrodes were characterized using cyclic voltammetry and potentiostatic charging in aqueous NaCl solutions (no = 20 - 90 mM) using a three electrode setup. Examination of the CV and potentiostatically-measured capacitances were consistent with EDL behavior dictated by the Stern layer. However, some deviations from the expected behavior were observed with increasing salt concentration during potentiostatic testing.

Download Full-text

Corrugated graphene layers for sea water desalination using capacitive deionization

Physical Chemistry Chemical Physics ◽

10.1039/c7cp00389g ◽

2017 ◽

Vol 19 (12) ◽

pp. 8552-8562 ◽

Cited By ~ 14

Author(s):

Madhavi Dahanayaka ◽

Bo Liu ◽

Zhongqiao Hu ◽

Zhong Chen ◽

Adrian Wing-Keung Law ◽

...

Keyword(s):

Sea Water ◽

Water Desalination ◽

Ion Adsorption ◽

Capacitive Deionization ◽

Graphene Layers ◽

Graphene Membrane

Graphene membrane corrugation highly enhances ion adsorption in the capacitive deionization process.

Download Full-text

Brackish water desalination by capacitive deionization using zinc oxide micro/nanostructures grafted on activated carbon cloth electrodes

Desalination ◽

10.1016/j.desal.2014.03.037 ◽

2014 ◽

Vol 344 ◽

pp. 236-242 ◽

Cited By ~ 68

Author(s):

Myo Tay Zar Myint ◽

Salim H. Al-Harthi ◽

Joydeep Dutta

Keyword(s):

Zinc Oxide ◽

Activated Carbon ◽

Brackish Water ◽

Water Desalination ◽

Carbon Cloth ◽

Capacitive Deionization ◽

Activated Carbon Cloth

Download Full-text

A brief review on operation of flow-electrode capacitive deionization cells for water desalination

10.5004/dwt.2021.27051 ◽

2021 ◽

Vol 223 ◽

pp. 34-53

Author(s):

Khadijeh Dehghan ◽

Seyed Ahmad Mirbagheri ◽

Mahdi Alam

Keyword(s):

Water Desalination ◽

Capacitive Deionization

Download Full-text

Integrated Capacitive Deionization and Humidification-Dehumidification System for Brackish Water Desalination

Energies ◽

10.3390/en14227641 ◽

2021 ◽

Vol 14 (22) ◽

pp. 7641

Author(s):

Sadam-Hussain Soomro ◽

Yusufu Abeid Chande Jande ◽

Salman Memon ◽

Woo-Seung Kim ◽

Young-Deuk Kim

Keyword(s):

Renewable Energy ◽

Salt Concentration ◽

Brackish Water ◽

Waste Heat ◽

Renewable Energy Sources ◽

Water Desalination ◽

Energy Sources ◽

Capacitive Deionization ◽

Combined System ◽

Flow Rates

A hybrid capacitive deionization and humidification-dehumidification (CDI–HDH) desalination system is theoretically investigated for the desalination of brackish water. The CDI system works with two basic operations: adsorption and regeneration. During adsorption, water is desalted, and during the regeneration process the ions from electrodes are detached and flow out as wastewater, which is higher in salt concentration. This wastewater still contains water but cannot be treated again via the CDI unit because CDI cannot treat higher-salinity waters. The discarding of wastewater from CDI is not a good option, since every drop of water is precious. Therefore, CDI wastewater is treated using waste heat in a process that is less sensitive to high salt concentrations, such as humidification-dehumidification (HDH) desalination. Therefore, in this study, CDI wastewater was treated using the HDH system. Using the combined system (CDI–HDH), this study theoretically investigated brackish water of various salt concentrations and flow rates at the CDI inlet. A maximum distillate of 1079 L/day was achieved from the combined system and the highest recovery rate achieved was 24.90% from the HDH unit. Additionally, two renewable energy sources with novel ideas are recommended to power the CDI–HDH system.

Download Full-text