Browsing by Author "Kim, Woo-Seung"

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Biomass-based carbon electrode materials for capacitive deionization: a review
(Springer Nature Switzerland AG., 2019-06-27) Elisadiki, Joyce; Kibona, Talam; Machunda, Revocatus; Saleem, Muhammad; Kim, Woo-Seung; Jande, Yusufu
Capacitive deionization (CDI) is a promising water purification technology which works by removing salt ions or charged species from aqueous solutions. Currently, most of the research on CDI focuses on the desalination of water with low or moderate salt concentration due to the low salt adsorption capacity of the electrodes. The electrosorption capacity of CDI relies on the structural and textural characteristics of the electrode materials. The cost of electrode materials, the complicated synthesis methods, and the environmental concerns arising from material synthesis steps hinder the development of large-scale CDI units. By considering the good electrical conductivity, high specific surface area (SSA), porous structure, availability, mass production, and cost, porous carbon derived from biomass materials may be a promising CDI electrode material. This review presents an update on carbon nanomaterials derived from various biomasses for CDI electrodes. It covers different synthesis methods and the electrosorption performance of each material and discusses the impact of the SSA and porous structure of the materials on desalination. This review shows that a variety of biomass materials can be used to synthesize cost-effective CDI electrode materials with different structures and good desalination performance. It also shows that diverse precursors and synthesis routes have significant influences on the properties and performance of the resulting carbon electrodes. Additionally, the performance of CDI does not depend only on BET surface area and pore structure but also on the applied voltage, initial concentration of the feed solution, and mass, as well as the capacitance of the electrodes.
Combined reverse osmosis and constant-current operated capacitive deionization system for seawater desalination
(Elsevier B.V., 2014-07-01) Minhas, Muhammad; Jande, Yusufu; Kim, Woo-Seung
There is an increase in the use of water purification technologies to produce the purified water from saline water. The desalination process may either involve the use of a single desalination technology, or may include the utilization of multiple desalination methods. In this study, reverse osmosis (RO) is integrated with the constant-current operated capacitive deionization (CCOCD) to desalinate seawater into high-quality ultrapure water, in addition to producing fresh water from the same system. For systems with the same feed concentration and feed flow rates, the RO–CCOCD hybrid system is superior to the RO–CVOCD (CVOCD is the constant voltage operated capacitive deionization) system. The advantages of RO–CCOCD over RO–CVOCD include a longer adsorption time for CDI cells with the same capacitance and spacer volume/dead volume as that of CVOCD, and increased quality of ultrapure water (> 18 MΩ cm) along-with its production. The specific energy consumption for the production of desalted water is generally the same for RO–CCOCD and RO–CVOCD given the same feed concentration and feed flow rate.
Desalination using capacitive deionization at constant current
(Elsevier B.V., 2013-11-15) Jande, Yusufu; Kim, Woo-Seung
Capacitive deionization (CDI) is an emerging technology of desalinating brackish/seawater to attain freshwater. The process involves polarization of the two electrodes electrically using direct current; thus the cations and anions are attracted towards the oppositely charged electrode. So far most of the experiments/models involve the charging of the CDI cell at constant voltage. However, charging at constant voltage leads to having a shorter time in a given CDI cell cycle when the system has reached its lowest effluent concentration. This is undesired phenomena. To overcome this problem desalination process is preferred to be performed at constant current. The dynamic response model to describe the variation of the effluent concentration with time under constant current charging has been derived and validated. Also, the effect of processing parameters such as applied current, flow rate, CDI cell dead volume, and capacitance on the lowest effluent concentration is analyzed.
Energy minimization in monoethanolamine‐based CO2 capture using capacitive deionization
(John Wiley & Sons, Ltd., 2014-01-07) Jande, Yusufu; Asif, Muhammad; Shim, S. M.; Kim, Woo-Seung
Post‐combustion CO2 capture using monoethanolamine (MEA) is a mature technology; however, the high energy input requirements for solvent regeneration are still a challenge for MEA‐based CO2 capture. In this paper, a novel approach is presented in which a conventional CO2 absorption–desorption system is integrated with capacitive deionization (CDI) in such a way to minimize the heat duty requirement of the stripper. The CO2‐rich solution drawn from the absorber column is first sent to CDI where ionic species are adsorbed at oppositely charged electrodes during the charging cycle, and an ion‐free solution is sent back to the absorber. The adsorbed ions released during the regeneration cycle are sent to the stripper column. The concentrated solution from the CDI process that was sent to the stripper required low heat duty to regenerate the solvent because of the high CO2 loading of the solution. The feasibility of the suggested modelling technique is verified at various stripper inlet temperatures and lean CO2 loadings. The results indicate that 10–45% of the total energy supplied to the stripper can be conserved at a lean CO2 loading of 0.0000–0.0323 using the suggested process model. Moreover, the required size of the stripper column will be small due to the small volume of the concentrated ionic solutions from the CDI cell, eliminating the initial cost of the CO2 capture system.
Integrated Capacitive Deionization and Humidification-Dehumidification System for Brackish Water Desalination
(MDPI, 2021-11-15) Soomro, Sadam-Hussain; Jande, Yusufu; Memon, Salman; Kim, Woo-Seung; Kim, Young-Deuk
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.
Integrating reverse electrodialysis with constant current operating capacitive deionization
(Elsevier Ltd., 2014-12-15) Jande, Yusufu; Kim, Woo-Seung
The presence of a salinity gradient between saline water streams may result in the production of electricity via either reverse electrodialysis (RED) or forward osmosis. While the former system generates electricity because of the ionic current, the latter process produces electricity due to the osmotic pressure. In this study, RED is coupled with capacitive deionization (CDI) so that highly pure water, fresh water and electricity could be generated simultaneously. A CDI cell is operated at constant current, and it generated ultrapure water and two streams (a lower salinity stream of approximately 17.4 mol NaCl per m3 and a high salinity stream of approximately 512.8 mol NaCl per m3) to be fed to the RED stack from a 15,000 ppm CDI feed concentration. The performed simulation reveals that, the total power generated from the RED using infinitely divided electrodes is 0.57 W/m2 electrode area. The use of RED in a CDI plant introduces a new approach to minimize CDI brine concentration, which would otherwise have a negative impact on the environment if it were disposed directly without prior treatment.
Modeling the capacitive deionization batch mode operation for desalination
(Elsevier, 2014-09-25) Jande, Yusufu; Kim, Woo-Seung
Capacitive deionization (CDI) is an emerging desalination technology in which saline water flows through a pair of polarized/biased electrodes. The cations and anions are attracted towards the negative and positive electrodes, respectively. In CDI operation there are two possible modes: single pass and batch mode. In single pass operation, saline water passes only once through the CDI cell, whereas in batch mode operation, the fixed volume of saline water is recycled continuously until a steady state is reached. This paper presents the transient response of the CDI cell under batch mode operation. The model is developed by taking into account single pass CDI operation and the mixing phenomena that occur in the recycling tank. The developed model was successfully validated using experimental data, and the model helped to derive the equation for predicting the steady state of the CDI cell for the given operating parameters: flow rate, saline water quantity, CDI capacitance, CDI resistance, spacer volume, dead volume, applied potential, and initial concentration of the saline water.
Performance optimization of integrated electrochemical capacitive deionization and reverse electrodialysis model through a series pass desorption process
(Elsevier, 2017-06-15) Saleem, Muhammad; Jande, Yusufu; Kim, Woo-Seung
A capacitive deionization (CDI) system is one of the emerging desalination technologies used to purify brackish water. It is an electrochemical technology that uses electrically charged porous electrodes to remove salt ions from water. In this study, we developed a process model by integrating CDI with reverse electrodialysis (RED) for the production of pure water and energy. RED is a power generation technology that uses the mixing entropy of water with high and low salt concentrations. Desalination with low energy consumption and high water recovery (WR) was a design preference for this integrated electrochemical model. CDI system was optimized with a series four pass reverse current desorption (RCD) method to achieve WR of almost 96.7% that was previously 50–80% on average. Moreover, an artificial salinity gradient was also produced for RED to generate energy through this four-pass RCD method of CDI. The concentration gain ratio (CGR), WR of CDI, and power density of RED was numerically assessed with different number of desorption passes and for CDI desorption current. WR and CGR value in CDI increased to 96% and 25, respectively, with the increase of number of desorption passes to four. Two stage RED cell system is used to get energy from salinity gradient produced through CDI. Energy consumption of 1.5 kJ/l for pure water production was reduced to 0.58 kJ/l with this purposed integrated four-pass CDI-RED system. This integrated electrochemical system reduced desalination energy consumption as well reducing environmental pollution with an eco-friendly, renewable power generation method and a reduction in the CDI disposal concentration.
Predicting the lowest effluent concentration in capacitive deionization
(Elsevier B.V., 2013-08-30) Jande, Yusufu; Kim, Woo-Seung
Capacitive deionization (CDI) is a promising technology for desalination of brackish water with different applications such as in the pharmaceutical industry, semiconductor manufacturing, and domestic use. The CDI cell utilizes an electric potential across two electrodes in which one of the electrodes becomes positively charged and the other becomes negatively charged. Cations and anions are attracted towards the anode and cathode, respectively. The adsorption and desorption mechanism within the CDI cell determines the amount of salt in the effluent stream. Modeling the dynamic response of the effluent concentration is vital to understanding the water purity level. In this paper, the equations predicting the lowest concentration time and lowest concentration have been found using the adsorption cycle mathematical model. During purification process the effluent concentration reaches the highest purity level after a certain period of time. We define the time it takes to reach the highest purity level as lowest concentration time and the corresponding instantaneous effluent purer water is what we call lowest concentration. While the lowest concentration depends on all of the CDI operating parameters i.e., applied potential, capacitance, flow rate, feed concentration, dead volume, and spacer volume, the lowest concentration time depends only on flow rate, dead volume, and capacitance. Using a genetic algorithm, it was found that seawater (32,702 ppm) could be desalinated to as low as 2.1 ppm; which is within the standards for drinking water set by the world health organization.
Ultrapure water from seawater using integrated reverse osmosis-capacitive deionization system
(Taylor & Francis Online, 2013-12-19) Jande, Yusufu; Minhas, Muhammad; Kim, Woo-Seung
The use of water for particular application depends on its purity level. In accordance with the world health organization, water with total dissolved salts (TDS) less than 500 ppm can be considered good for human consumption. Ultrapure water is used in areas such as semiconductor industry, pharmaceuticals, and laboratories. Purification processes like electrodeionization process, thermal processes, and membrane processes are used to produce ultrapure water from very low salinity (10–200 ppm) water source. In this study, seawater is desalinated to produce ultrapure water using the integrated reverse osmosis (RO)-capacitive deionization (CDI). The RO permeate is fed to the CDI cell to generate the high purity water. It has been found that, with the use of RO-CDI integrated system, seawater can be used to produce ultrapure water with TDS less than 2 ppm and potable water with TDS less than 400 ppm by consuming 3.171 kWh/m3 of energy. The proposed integrated RO-CDI system is of significant interest in the areas where ultrapure water along with fresh water is required from seawater.