Browsing by Author "Sufiani, Omari"

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    Enhanced electrosorption capacity of activated carbon electrodes for deionized water production through capacitive deionization
    (Elsevier, 2020) Sufiani, Omari; Hideki, Tanaka
    The deionized water (DI) of high purity standards is used in several industrial processes to manufacture products and technologies for high-end applications. Currently, DI water is produced by either reverse osmosis or continuous electrodeionization systems, however; both of them are facing several limitations. Therefore there is an urgent need for alternative technologies for DI water production. This study investigated the suitability of producing DI water by using capacitive deionization (CDI) with nitric acid-treated activated carbon electrodes (NTAC). Activated carbon (AC) was etched in nitric acid solution to introduce various oxygen functional groups on its surface. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to confirm the increased surface oxygen-containing groups on AC after nitric acid treatment that enhanced its salt adsorption capacity. CDI experiments were conducted using a water solution of 12.0 μS/cm as a result DI water with the conductivity of 1.6 μS/cm (DI water grade III, according to International Organization of Standards) was produced. Also, electrochemical tests revealed good capacitive behaviour due to improved conductivity with NTAC having the highest specific capacitance of 381.7 F/g compared to 106.6 F/g of AC electrode. This study provides an insight into the electrosorption performance of materials in desalination of solutions of low ionic strength.
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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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    Towards attaining SDG 6: The opportunities available for capacitive deionization technology to provide clean water to the African population
    (Elsevier, 2022) Sufiani, Omari; Sahini, Mtabazi G.; Elisadiki, Joyce
    The unavailability of clean water caused by population growth, increased industrial activities, and global climate change is a major challenge in many communities. A number of desalination technologies including distillation, reverse osmosis and electrodialysis, have been used to supplement the available water resources. However, these technologies are energy intensive and demand a significant financial commitment. Capacitive deionization (CDI) is an emerging desalination technology which is promising to provide water at a reasonable cost, especially in societies with limited incomes such as those in Africa. The opportunities for CDI to provide clean water to the African population are discussed in this paper. These opportunities include electrosorption at low potential, low energy consumption, large quantities of agricultural wastes for the production of electrode materials, high sunshine irradiation throughout the year, suitability for disinfection and defluoridation and its applications in the removal of heavy metals and emerging pollutants. Due to the existence of numerous enabling conditions, the analysis from this paper demonstrates that CDI can be a dependable method to provide clean water in Africa.