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.

scholarly journals Flow-electrode capacitive deionization enables continuous and energy-efficient brine concentration

2020 ◽  
Author(s):  
Matthias Wessling
Keyword(s):  
Energy Demand ◽  
Saline Water ◽  
Ionic Species ◽  
Economic Feasibility ◽  
Water Desalination ◽  
Capacitive Deionization ◽  
High Concentration ◽  
Agricultural Applications ◽  
High Concentrations ◽  
Desalination Technology

Many industrial and agricultural applications require the treatment of water streams containing high concentrations of ionic species for closing material cycles. High concentration factors are often desired, but hard to achieve with established thermal or membrane-based water treatment technologies at low energy consumptions. Capacitive deionization processes are normally assumed as relevant for the treatment of low salinity solutions only. Flowelectrode capacitive deionization (FCDI), on the other hand, is an upcoming electrically driven water desalination technology, which allows the continuous desalination and concentration of saline water streams even at elevated salinities. Ions are adsorbed electrostatically in pumpable carbon flow electrodes, which enable a range of new process designs.In this article, it is shown that continuously operated FCDI systems can be applied for the treatment of salt brines. Concentrations of up to 291.5 g/L NaCl were reached in the concentrate product stream. Based on this, FCDI is a promising technology for brine treatment and salt recovery. Additionally, a reduction of the energy demand by more than 70% is demonstrated by introducing multiple cell pairs into a continuous FCDI system. While the economic feasibility is not investigated here, the results show that FCDI systems may compete with established technologies regarding their energydemand.

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.

scholarly journals Nano-manganese oxide and reduced graphene oxide incorporated polyacrylonitrile fiber mats as electrode material for capacitive deionization (CDI) technology

2021 ◽  
Author(s):  
Nalin De Silva ◽  
Induni Siriwardena ◽  
Nadeesha P. W. Rathuwadu ◽  
Damayanthi Dahanayake ◽  
Chanaka Sandaruwan ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Manganese Dioxide ◽  
Reduced Graphene Oxide ◽  
Electrode Material ◽  
Water Desalination ◽  
Polyacrylonitrile Fiber ◽  
Capacitive Deionization ◽  
Fiber Mats ◽  
Reduced Graphene ◽  
Impurity Ions

Capacitive deionization (CDI) is a trending water desalination method, during which the impurity ions in water can be removed by electrosorption. In this study, nano-manganese dioxide (MnO2) and reduced graphene...

scholarly journals Efficient Desalination of Brackish Ground Water via a Novel Capacitive Deionization Cell Using Nanoporous Activated Carbon Cloth Electrodes

2015 ◽  
Vol 12 (2) ◽  
pp. 22 ◽  
Author(s):  
K. Laxman ◽  
M.T.Z Myint ◽  
M. Al Abri ◽  
L. Al-Gharibi ◽  
B. Al Namani ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Ground Water ◽  
Brackish Water ◽  
Water Samples ◽  
Sea Water ◽  
Water Desalination ◽  
Carbon Cloth ◽  
Capacitive Deionization ◽  
Activated Carbon Cloth ◽  
Nanoporous Activated Carbon

Sea water intrusion in ground water sources has made brackish water desalination a necessity in Oman. The application of capacitive deionization (CDI) for the deionization of ground water samples from wells in Al-Musanaah Wilayat is proposed and demonstrated. A CDI cell is fabricated using nanoporous activated carbon cloth (ACC) as the electrodes and is shown to be power efficient for desalting ground water samples with total dissolved solids (TDS) of up to 4,000 mg/l. The CDI cell was able to remove up to 73% of the ionic scaling and fouling contaminants from brackish water samples. The power consumption for deionization of brackish water was estimated to be 1 kWh/m3 of desalinated water, which is much lower than the power required to process water with equivalent TDS by the reverse osmosis processes. The CDI process is elaborated, and observations and analysis of the ion adsorption characteristics and electrical properties of the capacitive cell are elucidated.  

scholarly journals Synthesis and Characterization of Activated Carbon Co-Mixed Electrospun Titanium Oxide Nanofibers as Flow Electrode in Capacitive Deionization

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6891
Author(s):  
Gbenro Folaranmi ◽  
Myriam Tauk ◽  
Mikhael Bechelany ◽  
Philippe Sistat ◽  
Marc Cretin ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Titanium Oxide ◽  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Electrospinning Process ◽  
Water Desalination ◽  
Capacitive Deionization ◽  
Interfacial Resistance ◽  
X Ray ◽  
Electrode Passivation

Flow capacitive deionization is a water desalination technique that uses liquid carbon-based electrodes to recover fresh water from brackish or seawater. This is a potential second-generation water desalination process, however it is limited by parameters such as feed electrode conductivity, interfacial resistance, viscosity, and so on. In this study, titanium oxide nanofibers (TiO2NF) were manufactured using an electrospinning process and then blended with commercial activated carbon (AC) to create a well distributed flow electrode in this study. Field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray (EDX) were used to characterize the morphology, crystal structure, and chemical moieties of the as-synthesized composites. Notably, the flow electrode containing 1 wt.% TiO2NF (ACTiO2NF 1 wt.%) had the highest capacitance and the best salt removal rate (0.033 mg/min·cm2) of all the composites. The improvement in cell performance at this ratio indicates that the nanofibers are uniformly distributed over the electrode’s surface, preventing electrode passivation, and nanofiber agglomeration, which could impede ion flow to the electrode’s pores. This research suggests that the physical mixture could be used as a flow electrode in capacitive deionization.

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