Performance Improvement of Capacitive Deionization for Water Desalination Using a Multistep Buffered Approach

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Yasamin Salamat ◽  
Carlos A. Rios Perez ◽  
Carlos Hidrovo
Keyword(s):  
Flow Rate ◽  
Porous Electrodes ◽  
Water Desalination ◽  
Low Flow ◽  
Lower Amount ◽  
Capacitive Deionization ◽  
Innovative Methods ◽  
Intermediate Solution ◽  
Improved Performance ◽  
Increasing Demand

Due to the increasing demand for clean and potable water stemming from population growth and exacerbated by the scarcity of fresh water resources, more attention has been drawn to innovative methods for water desalination. Capacitive deionization (CDI) is a low maintenance and energy efficient technique for desalinating brackish water, which employs an electrical field to adsorb ions into a high-porous media. After the saturation of the porous electrodes, their adsorption capacity can be restored through a regeneration process. Herein, based on a physical model previously developed, we conjecture that for a given amount of time and volume of water, multiple desalination cycles in a high flow rate regime will outperform desalinating in a single cycle at a low flow rate. Moreover, splitting a CDI unit into two subunits, with the same total length, will lead to higher desalination. Based on these premises, we introduce a new approach aimed at enhancing the overall performance of CDI. An array of CDI cells are sequentially connected to each other with intermediate solutions placed in between them. Desalination tests were conducted to compare the performance of the proposed system, consisting of two CDI units and one intermediate solution buffer, with a two-cascaded-CDI unit system with no intermediate solution. Experimental data demonstrated the improved performance of the buffered system over the nonbuffered system, in terms of desalination percentage and energy consumption. The new proposed method can lead to lower amount of energy consumed per unit volume of the desalinated water.

Performance Improvement of Capacitive Deionization for Water Desalination Using a Multi-Step Buffered Approach

2016 ◽  
Author(s):  
Yasamin Salamat ◽  
Carlos A. Rios Perez ◽  
Carlos Hidrovo
Keyword(s):  
Flow Rate ◽  
High Flow ◽  
Porous Electrodes ◽  
High Flow Rate ◽  
Water Desalination ◽  
Lower Amount ◽  
Capacitive Deionization ◽  
Outlet Concentration ◽  
Overall Performance ◽  
Intermediate Solution

Due to the increasing demand for clean and potable water stemming from population growth and exacerbated by the scarcity of fresh water resources, more attention has been drawn to different and innovative methods for water desalination. Capacitive deionization (CDI) is a relatively new, low maintenance, and energy efficient technique for desalinating brackish water. In this technique, an electrical field is employed to adsorb ions into a high-porous media. After the saturation of the porous electrodes, their adsorption capacity can be restored through a regeneration process. Various parameters affect the overall performance of CDI. The flow rate at which water is purified in CDI plays an essential role in its ultimate performance. Many studies have shown that desalination percentage decreases as flow rate increases in CDI, since the advection of ions in the flow becomes more dominant than their diffusion toward the electrodes. However, herein, based on a physical model previously developed, we conjecture that for a given amount of time and volume of water, multiple desalination cycles in a high flow rate regime will outperform desalinating in a single cycle at a low flow rate. Moreover, splitting a CDI unit into two sub-units, with the same total length, will lead to higher desalination. Based on these premises, we introduce a new approach aimed at enhancing the overall performance of CDI. An array of CDI cells are sequentially connected to each other with intermediate solutions placed in between them. These intermediate solutions act as buffers to homogenize the outlet concentration of the preceding cell and maintain a constant inlet concentration for the following cell. Desalination tests were conducted to compare the performance of the proposed system, consisting of two CDI units and one intermediate solution buffer, with a two-cascaded-CDI unit system with no intermediate solution. Desalination tests were performed in a high flow rate regime with a low salinity initial solution of NaCl in water. In the buffered arrangement, the concentration of the solution buffer was set at the minimum average outlet concentration of the first CDI test. Experimental data demonstrated the improved performance of the buffered system over the non-buffered system, in terms of desalination percentage and energy consumption. Increasing the number of CDI units and solution buffers in a buffered system, the new proposed method will lead to lower amount of energy consumed per unit volume of the desalinated water.

Performance Characterization of a Capacitive Deionization Water Desalination System With an Intermediate Solution and Low Salinity Water

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Yasamin Salamat ◽  
Carlos A. Rios Perez ◽  
Carlos Hidrovo
Keyword(s):  
Industrial Applications ◽  
Water Desalination ◽  
Capacitive Deionization ◽  
Steady State Condition ◽  
Low Salinity ◽  
In Series ◽  
Salinity Water ◽  
Intermediate Solution ◽  
Preceding Cell

In recent years, more efforts have been made to improve new and more efficient nonmembrane-based methods for water desalination. Capacitive deionization (CDI), a novel technique for water desalination using an electric field to adsorb ions from a solution to a high-porous media, has the capability to recover a fraction of the energy consumed for the desalination during the regeneration process, which happens to be its most prominent characteristic among other desalination methods. This paper introduces a new desalination method that aims at improving the performance of traditional CDI systems. The proposed process consists of an array of CDI cells connected in series with buffer containers in between them. Each buffer serves two purposes: (1) averaging the outlet solution from the preceding cell and (2) securing a continuous water supply to the following cell. Initial evaluation of the proposed CDI system architecture was made by comparing a two-cell-one-buffer assembly with a two cascaded cells array. Concentration of the intermediate solution buffer was the minimum averaged concentration attained at the outlet of the first CDI cell, under a steady-state condition. The obtained results show that the proposed CDI system with intermediate solution had better performance in terms of desalination percentage. This publication opens new opportunities to improve the performance of CDI systems and implement this technology on industrial applications.

Performance Characterization of a Capacitive Deionization Water Desalination System With an Intermediate Solution and Low Salinity Water

2015 ◽  
Author(s):  
Seyedehyasamin Salamat ◽  
Carlos A. Rios Perez ◽  
Carlos Hidrovo
Keyword(s):  
Industrial Applications ◽  
Water Desalination ◽  
Capacitive Deionization ◽  
Steady State Condition ◽  
Low Salinity ◽  
In Series ◽  
Salinity Water ◽  
Intermediate Solution ◽  
Preceding Cell

In recent years, more efforts have been made to improve new and more efficient non-membrane-based methods for water desalination. Capacitive deionization (CDI), a novel technique for water desalination using an electric field to adsorb ions from a solution to a high-porous media, has the capability to recover a fraction of the energy consumed for the desalination during the regeneration process, which happens to be its most prominent characteristic among other desalination methods. This paper introduces a new desalination method that aims improving the performance of traditional CDI systems. The proposed process consists of an array of CDI cells connected in series with buffer containers in between them. Each buffer, serve two purposes: 1) average the outlet solution from the preceding cell, and 2) secure a continuous water supply to the following cell. Initial evaluation of the proposed CDI system architecture was made by comparing a two-cell-one-buffer assembly with a two cascaded cells array. Concentration of the intermediate solution buffer was the minimum averaged concentration attained at the outlet of the first CDI cell, under a steady state condition. The obtained results show that proposed CDI system with intermediate solution had better performance in terms of desalination percentage. This publication opens new opportunities to improve the performance of CDI systems and implement this technology on industrial applications.

scholarly journals Comparative Investigation of Activated Carbon Electrode and a Novel Activated Carbon/Graphene Oxide Composite Electrode for an Enhanced Capacitive Deionization

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5185
Author(s):  
Gbenro Folaranmi ◽  
Mikhael Bechelany ◽  
Philippe Sistat ◽  
Marc Cretin ◽  
Francois Zaviska
Keyword(s):  
Graphene Oxide ◽  
Activated Carbon ◽  
Comparative Investigation ◽  
Operating Conditions ◽  
Porous Electrodes ◽  
Water Desalination ◽  
Capacitive Deionization ◽  
Oxide Electrodes ◽  
Desalination Technology ◽  
Operating Window

Capacitive deionization is an emerging brackish water desalination technology whose principle lies in the utilization of porous electrodes (activated carbon materials) to temporarily store ions. Improving the properties of carbon material used as electrodes have been the focus of recent research, as this is beneficial for overall efficiency of this technology. Herein, we have synthesized a composite of activated carbon/graphene oxide electrodes by using a simple blending process in order to improve the hydrophilic property of activated carbon. Graphene oxide (GO) of different weight ratios was blended with commercial Activated carbon (AC) and out of all the composites, AC/GO-15 (15 wt.% of GO) exhibited the best electrochemical and salt adsorption performance in all operating conditions. The as prepared AC and AC/GO-x (x = 5, 10, 15 and 20 wt.% of GO) were characterized by cyclic voltammetry and their physical properties were also studied. The salt adsorption capacity (SAC) of AC/GO-15 at an operating window of 1.0 V is 5.70 mg/g with an average salt adsorption rate (ASAR) of 0.34 mg/g/min at a 400 mg/L salt initial concentration and has a capacitance of 75 F/g in comparison to AC with 3.74 mg/g of SAC, ASAR of 0.23 mg/g/min and a capacitance of 56 F/g at the same condition. This approach could pave a new way to produce a highly hydrophilic carbon based electrode material in CDI.

scholarly journals Activated Carbon Blended with Reduced Graphene Oxide Nanoflakes for Capacitive Deionization

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1090
Author(s):  
Gbenro Folaranmi ◽  
Mikhael Bechelany ◽  
Philippe Sistat ◽  
Marc Cretin ◽  
Francois Zaviska
Keyword(s):  
Graphene Oxide ◽  
Activated Carbon ◽  
Reduced Graphene Oxide ◽  
Electrode Materials ◽  
Porous Electrodes ◽  
Water Desalination ◽  
Operating Voltage ◽  
Capacitive Deionization ◽  
X Ray ◽  
Reduced Graphene

Capacitive deionization is a second-generation water desalination technology in which porous electrodes (activated carbon materials) are used to temporarily store ions. In this technology, porous carbon used as electrodes have inherent limitations, such as low electrical conductivity, low capacitance, etc., and, as such, optimization of electrode materials by rational design to obtain hybrid electrodes is key towards improvement in desalination performance. In this work, different compositions of mixture of reduced graphene oxide (RGO) and activated carbon (from 5 to 20 wt% RGO) have been prepared and tested as electrodes for brackish water desalination. The physico-chemical and electrochemical properties of the activated carbon (AC), reduced graphene oxide (RGO), and as-prepared electrodes (AC/RGO-x) were characterized by low-temperature nitrogen adsorption measurement, scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red (FT-IR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Among all the composite electrodes, AC/RGO-5 (RGO at 5 wt%) possessed the highest specific capacitance (74 F g−1) and the highest maximum salt adsorption capacity (mSAC) of 8.10 mg g−1 at an operating voltage ∆E = 1.4 V. This shows that this simple approach could offer a potential way of fabricating electrodes of accentuated carbon network of an improved electronic conductivity that’s much coveted in CDI technology.

Energy Consumption in Batch-Mode Capacitive Deionization

2016 ◽  
Vol 868 ◽  
pp. 43-49 ◽  
Author(s):  
Hai Bo Li ◽  
Sen Liang ◽  
Mang Mang Gao ◽  
Chang Yeoul Kim
Keyword(s):  
Energy Consumption ◽  
Cell Voltage ◽  
Solution Concentration ◽  
Porous Electrodes ◽  
Water Desalination ◽  
Double Layers ◽  
Capacitive Deionization ◽  
Batch Mode ◽  
Operation Conditions ◽  
Salt Ions

Capacitive deionization (CDI) is a water desalination technique in which salt ions are removed from brackish water by flowing through a spacer channel with porous electrodes on each side. Upon applying a small voltage difference between the two electrodes, cations move to and are accumulated in electrostatic double layers inside the negatively charged cathode and the anions are removed by the positively charged anode. Therefore, one of the advanced merits of CDI is the low driven energy by compared to other desalination technologies. Inspired this, we have performed the calculation on energy consumption of activated carbon based CDI in different operation conditions. The results show that the energy consumptions are significantly related to cell voltage as well as solution concentration. Furthermore, the round trip efficiency as a vital indication in terms of energy consumption have been introduced and discussed as well.

DESALINATION BY CAPACITIVE DEIONIZATION WITH CARBON-BASED MATERIALS AS ELECTRODE: A REVIEW

2013 ◽  
Vol 20 (06) ◽  
pp. 1330003 ◽  
Author(s):  
WEI HUANG ◽  
YIMIN ZHANG ◽  
SHENXU BAO ◽  
SHAOXIAN SONG
Keyword(s):  
Influencing Factors ◽  
Flow Rate ◽  
Electrode Materials ◽  
Feed Solution ◽  
Porous Electrodes ◽  
Operating Parameters ◽  
Capacitive Deionization ◽  
Adsorption Models ◽  
Research Status ◽  
Carbon Based

Capacitive deionization (CDI) is a recently developed electrosorption technology for deionization using porous electrodes. The electrode materials play an important role in the efficiency. This paper highlights the current research status of carbon-based materials as the electrode and the adsorption models in the CDI. It includes the types and performances of carbon-based materials and the main influencing factors of the desalination characteristics. Also, operating parameters such as charging voltage, flow rate, concentration of feed solution, treating time and temperature are summarized.

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