Browsing by Author "Elisadiki, Joyce"
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Item 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.Item Capacitive deionization for the removal of paraquat herbicide from aqueous solution(Sage publishing and Hindawi, 2021) Alfredy, Tusekile; Elisadiki, Joyce; Jande, Yusufu Abeid ChandeIn comparison to other conventional methods like adsorption and reverse osmosis (RO), capacitive deionization (CDI) has only been investigated extensively for the removal of inorganic pollutants from water, demonstrating limited practicality. Herein, the study investigated the use of CDI for the removal of paraquat (PQ) herbicide from water by using commercial activated carbon (AC) electrodes. The CDI performance was examined as a function of the initial PQ concentration, applied voltage, flowrate, treatment time, and cycle stability testing in the batch mode approach. The applied voltage had a beneficial effect on the removal efficiency, whereas the removal efficiency of PQ declined as the initial PQ concentration increased. However, the electrosorption capacity gradually increased with the increase of initial feed solutions’ concentration. The maximum removal efficiency and electrosorption capacity achieved at 5 mg/L and 20 mg/L PQ initial concentrations, an applied voltage of 1.2 V, and 5 mL/min flowrate were 100% and 0.33 mg/g and 52.5% and 0.7 mg/g, respectively. Washing the electrodes with distilled water achieved sequential desorption of PQ, and the process produces a waste stream that can be disposed of or treated further. Therefore, the CDI method is considered a promising and efficient method for removing organic pollutants from water including pesticides.Item Capacitive deionization: a promising technology for water defluoridation: a review(IWA Publishing, 2022) Alfredya, Tusekile; Elisadiki, Joyce; Jandea, Yusufu Abeid ChandeCapacitive deionization (CDI) is among the promising technologies employed for water purification. CDI has been studied for the removal of various ionic species from water including fluoride ion (F ) with promising results. However, there is no comprehensive literature that summarizes the use of CDI for water defluoridation applications. Therefore, this review paper critically analyzes different electrode materials that have been studied for water defluoridation, their electrosorption capacities and F removal efficiencies. It further discussed the parameters that influence CDI efficiency during defluoridation and point out the issues of F selectivity when co-existing with other ions in the solution. We can conclude that different electrode materials have shown different abilities in electrosorption of F . The carbon-based materials possess high surface area and good electrical conductivity which is paramount for ion adsorption but gives lack selectivity for F removal. Metal oxides and hydroxides have been reported with improved electrosorption capacity and high selectivity to F due to the ion exchange between the F and the hydroxyls surface of the metal oxides/hydroxides. Apart from the good performance of these materials for defluoridation, the discovery of actual practical use of the electrode materials for defluoridation for commercial scale is still a need.Item Electrosorption of paraquat pesticide on activated carbon modified by aluminium oxide (Al2O3) with capacitive deionization(Elsevier BV, 2024) Alfredy, Tusekile; Elisadiki, Joyce; Dahbi, Mouad; King'ondu, Cecil K.; Jande, Yusufu Abeid ChandeComposite electrode materials for removing paraquat from contaminated water were synthesized by loading aluminium oxide (Al2O3) onto activated carbon (AC) via co-precipitation method. The composite properties were investigated by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. Capacitive deionization batch experiments compared the electrosorption of paraquat herbicide by the composite electrode and the pristine activated carbon. The performance of the composite electrodes showed that the removal efficiency and adsorption capacity depend on the aluminium oxide loading, applied potential, flow rate, and charging time. At 1.2 V, a flow rate of 15 mL/min, a charging time of 3 h and 20 mg/L PQ initial concentration, the composite electrode (AC/Al2O3-1:1) demonstrated a removal efficiency, electrosorption capacity, and energy consumption of 95.5 %, 1.27 mg/g, and 0.055 kWh/m3, respectively, compared to 62 %, 0.83 mg/g, and 0.11 kWh/m3 for the unmodified AC. The presences of other ions/pollutants were found to have negligible interference on PQ pesticide removal as the removal efficiency and electrosorption capacity of the AC/Al2O3-1:1 composite in both artificial (95.5 %, 1.27 mg/g) and natural water (87.5 % 1.17 mg/g). The study confirmed that composite electrode can reused several times, as there was no significant decrease in its regeneration efficiency even after multiple cycles.Item Ferroelectric relaxor behaviour in Bi and K/Na-substituted solid solutions of tetragonal tungsten bronze PbNb2O6(Elsevier BV, 2024) Sahini, Mtabazi Geofrey; Mwankemwa, Benard Samwel; Elisadiki, JoyceLead metaniobate (PbNb2O6 or PNO) belongs to the tetragonal tungsten bronze (TTB) family. There are three polymorphic forms of PNO: tetragonal (stable at high temperature), rhombohedral (stable at room temperature), and the metastable orthorhombic phase, which has ferroelectric properties. The metastable orthorhombic phase is formed by quenching from the high temperature tetragonal phase due to the reconstructive/sluggish tetragonal to rhombohedral phase transition. A suitable ionic substitution can also lead to the stable ferroelectric orthorhombic phase. Stabilization of the ferroelectric orthorhombic phase by ionic substitution, and the formation of ferroelectric relaxors with increased amounts of dopants is hereby reported for the compositions Pb(1-x)Bi(x/2K(x/2)Nb2O6 and Pb(1-x)Bi(x/2)Na(x/2)Nb2O6. The solid solutions of PNO showed evidence of linked dielectric relaxation and ferroelectricity, validating the distinctive ferroelectric relaxor behaviour for the compositions Pb0.6Bi0.2K0.2Nb2O6 and Pb0.6Bi0.2Na0.2Nb2O6. As the concentrations of bismuth (Bi) and potassium/sodium (K/Na) dopants increased, the Curie temperature (Tc), or the temperature corresponding to the maximum dielectric permittivity (Tm), dropped. By using the Uchino-Nomura relation as a modification of the Curie-Weiss law, it was established that the Pb0.6Bi0.2K0.2Nb2O6 solid solution exhibit higher degree of diffuseness than Pb0.6Bi0.2Na0.2Nb2O6 at the transitions. The width of the ferroelectric hysteresis loop increased as the percentage of dopants increased, from x = 0.1 to x = 0.3. At x = 0.4, a narrow ferroelectric hysteresis loop and a frequency-dependent Tm abruptly formed, which is indicative of a ferroelectric relaxor.Item Highly porous biomass-based capacitive deionization electrodes for water defluoridation(Springer, 2019) Elisadiki, Joyce; Jande, Yusufu A.C.; Kibona, Talam Enock; Machunda, Revocatus LazaroThe 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.Item 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.Item Performance of ion intercalation materials in capacitive deionization/electrochemical deionization: A review(Elsevier, 2020) Elisadiki, Joyce; King'ondu, Cecil K.Capacitive deionization (CDI) also referred to as electrochemical deionization (EDI) is a deionization technology which depends on the electrical potential difference applied between a pair of electrodes to extract charged species from the solution. Due to their low cost, good electrical conductivity, porous structure, and high specific surface area, carbon materials have been the materials of choice for electrodes in most CDI cells. With carbon-based materials, ions from solution are extracted through electrosorption mechanism and stored in the electrical double layer (EDL) formed on the electrode surface. Recently, ion intercalation materials that store ions through pseudocapacitive ion intercalation have attracted interest. In pseudocapacitive ion intercalation mechanism, ions are inserted or stored in the lattice crystal structure sites of the intercalation host compounds (IHCs) due to redox reactions. The desalination performance of these materials, also referred to as salt adsorption capacity (SAC) and expressed in mg/g is reported to be higher compared to that of carbon-based electrode materials. The enhanced SAC of intercalation materials is due to the fact that ions are not only removed from the solution via surface adsorption but also through transfer of charge and intercalation/insertion of the ions into their crystallographic sites. To date, there is inadequate number of articles summarizing the performance of intercalation materials and strategies undertaken to improve performance thereof for desalination and ion separation purposes. This paper therefore, reviewed the performance of different intercalation electrode materials for water desalination presented in the literature to date. The discussion covers different geometries/architecture of a desalination cell utilizing ion intercalation materials, performance of ion intercalation materials and their mechanism of deionization as well as strategies that have been employed to improve their deionization performance. Furthermore, this paper provides an outlook and research niches existing in the field of ion intercalation materials for desalination applications and selective removal of both mono and divalent ions from aqueous solutions.Item Porous carbon derived from Artocarpus heterophyllus peels for capacitive deionization electrodes(Elsevier, 2019) Elisadiki, Joyce; Jande, Yusufu A.C.; Machunda, Revocatus L.; Kibona, Talam EnockSustainable 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.Item Promoting hands-on science learning globally with low-cost lab kits through Women Supporting Women in the Sciences(Elsevier BV, 2024) Elisadiki, Joyce; China, Cecilia Rolence; Wenderott, JillWomen Supporting Women in the Sciences (WS2)—ws2global.org—is an international initiative unifying and supporting graduate- and professional-level women and allies in science, technology, engineering, and mathematics (STEM), while providing outreach to elementary and secondary-level students. WS2 has been involved in the development of professional development workshops intended to empower university women and promote STEM careers. In their most recent venture, WS2 distributed low-cost physics and materials science lab kits that were designed virtually by international teams. These kits are relevant to elementary and secondary school students across the world, with an initial focus on local schools in eastern Africa. In this Backstory, part of the WS2 leadership team (Dr. Joyce Elisadiki, Dr. Cecilia Rolence China, and Dr. Jill Wenderott) discusses how the LabKit Initiative came together and highlights outcomes and lessons learned from this project.Item Promoting hands-on science learning globally with low-cost lab kits through Women Supporting Women in the Sciences(Elsevier BV, 2024) Elisadiki, Joyce; China, Cecilia Rolence; Wenderott, JillWomen Supporting Women in the Sciences (WS2)—ws2global.org—is an international initiative unifying and supporting graduate- and professional-level women and allies in science, technology, engineering, and mathematics (STEM), while providing outreach to elementary- and secondary-level students. WS2 has been involved in the development of professional development workshops intended to empower university women and promote STEM careers. In their most recent venture, WS2 distributed low-cost physics and materials science lab kits that were designed virtually by international teams. These kits are relevant to elementary and secondary school students across the world, with initial focus on local schools in eastern Africa. In this Backstory, part of the WS2 leadership team (Dr. Joyce Elisadiki, Dr. Cecilia Rolence China, and Dr. Jill Wenderott) discusses how the Lab Kit Initiative came together and highlights outcomes and lessons learned from this project.Item 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, JoyceThe 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.