Browsing by Author "Kibona, Talam Enock"

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    Biomass-based carbon electrode materials for capacitive deionization: A review
    (Springer Nature, 2019) Elisadiki, Joyce; Kibona, Talam Enock; Machunda, Revocatus L.; Saleem, Muhammad Wajid; Kim, Woo-Seung; Jande, Yusufu A. C.
    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.
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    Highly porous biomass-based capacitive deionization electrodes for water defluoridation
    (Springer, 2019) Elisadiki, Joyce; Jande, Yusufu A.C.; Kibona, Talam Enock; Machunda, Revocatus Lazaro
    The high concentration of fluoride (F−) in water sources is the main challenge in major fluoride belts. Though capacitive deionization (CDI) with porous carbon electrodes is the promising alternative in removing charged species from aqueous solution, little has been presented on the usefulness of CDI with biomass-based electrodes in removing F− from natural water existing together with other ions such as Ca2+ and Mg2+. This study investigated the feasibility of using biomass-based electrodes for natural water defluoridation application. Porous carbon was synthesized from jackfruit peels (JFAC) through potassium hydroxide (KOH) activation. Surface morphology, pore structure, and electrochemical properties of the JFAC were investigated. The textural properties of the synthesized carbon and electrochemical characteristics of the fabricated electrodes were found to be influenced by activation temperature. Brunauer-Emmett-Teller (BET) surface area, pore diameter, pore volume, and pore surface area increased with an increase in activation temperature and KOH to carbon ratio. It was further confirmed that as the applied voltage increased from 1.2 to 2 V, the amount of adsorbed anions increased without significantly affecting the pH of the water. At 2.0 V, the electrodes showed a maximum F− adsorption efficiency and electrosorption capacity of 62% and 0.13 mg/g respectively. The electrosorption capacity depends on the initial concentration of the ion in the feed water. It was further observed that natural organic substances contained in the natural water might inhibit JFAC electrode surface and decrease its adsorption efficiency. This study provides cost-effective CDI electrode material prepared from biomass for water defluoridation.
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    Porous carbon derived from Artocarpus heterophyllus peels for capacitive deionization electrodes
    (Elsevier, 2019) Elisadiki, Joyce; Jande, Yusufu A.C.; Machunda, Revocatus L.; Kibona, Talam Enock
    Sustainable clean water for human use can be attained through cost effective water purification technologies where by capacitive deionization (CDI) technology is among them. To attain high CDI performance porous carbon materials with good electrical conductivity, high surface area, specific capacitance and good chemical stability are essential. In this study high surface area porous carbon has been synthesized through carbonization of agricultural waste jackfruit peels (Artocarpus heterophyllus) followed by KOH activation at 600, 700, and 800 °C for 1 h. It was found that, the activation temperature significantly increased the BET surface area of the synthesized carbon from 607 m2/g to 1955 m2/g. Desalination experiments were carried out with 30–500 mg/L NaCl solution in batch mode at a flow rate of 2.5 ml/min while applying voltage of 1.2, 1.4 and 2.0 V to the cell. The electrosorption capacity and salt-removal efficiency increased with increasing BET Surface area and applied potential. Specifically, ACJF1:1-700 exhibited highest specific capacitance of 307 F/g, high salt removal efficiency and electrosorption capacity of 5.74 mg/g when voltage of 2 V was applied. These results indicated that the Artocarpus heterophyllus can be promising CDI electrode materials for low salinity water desalination.