Browsing by Author "Saleem, Muhammad"

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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.
Hybrid CV-CC operation of capacitive deionization in comparison with constant current and constant voltage
(Taylor & Francis Online, 2016-02-24) Saleem, Muhammad; Jande, Yusufu; Asif, Muhammad
Capacitive deionization (CDI) is a technique used to desalinate saline water by means of electrical potential applied to the electrode along both sides of a spacer channel through which water flows. CDI operates either at constant voltage (CV) or at constant current (CC) operation to desalinate saline water. The purity of the water is the main requirement at the outlet of the cell. The lowest effluent concentration is achieved within a very short time by operating the CDI cell at CV, but after that the effluent concentration continues to increase. On the other hand, in CC, the lowest concentration is achieved later as compared with CV, but once it is achieved it continues to remain constant until the target voltage is reached. In this paper, we combine both CV and CC operation to get the lowest concentration for maximum time during the adsorption process so that more desalinated water is produced. We compare hybrid CV-CC and constant voltage and constant current in terms of effluent concentration, energy consumption per ion removal, water recovery, and water quality by varying operational parameters like cell potential. It was observed that ultrapure water can be produced with hybrid CV-CC operation by systematically varying different process parameters like flow rate and cell potential to get better results.
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.