Browsing by Author "Jande, Yusufu A.C."

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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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    Modification strategies to enhance electrosorption performance of activated carbon electrodes for capacitive deionization applications
    (Elsevier, 2019) Sufiani, Omari; Elisadiki, Joyce; Machunda, Revocatus L.; Jande, Yusufu A.C.
    Capacitive deionization (CDI) is the competitive technology for water desalination which appears to become an alternative to conventional methods such as ion exchange resins, reverse osmosis, and electrodeionization. Variety of materials including, carbide-derived carbon, activated carbons, carbon nanotubes, carbon aerogels and mesoporous carbons have been studied for CDI applications most of them being porous carbons. However, materials such as carbon nanotubes are highly expensive and hinder applications at large industrial scale. Activated carbon is a cheap and commercially available electrode material for CDI though its desalination capacity is limited by factors such as low electrical conductivity, inability to selectively remove specific ions, co-ion expulsion, poor wettability, inappropriate pore size distribution and lack of inter-pore connectivity to enable ion diffusion. These factors have raised a concern to most researchers and try to find a way to modify the surface of porous materials. Some strategies have been used to modify activated carbons including dip-coating in dopamine solution, mixing with quaternized poly (4-vinylpyridine), combining with graphenes and carbon nanotubes, direct fluorination and etching in acid solution to mention few. This review highlight factor(s) that cause low performance of activated carbon and modification strategies used to treat activated carbon to enhance its adsorption performance. Furthermore, characterization methods used to confirm whether the modification was successful and the practical application of modification methods have been discussed. To our view this work will provide an understanding of the contribution offered by modified activated carbon electrodes in the development of CDI technology.
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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.