Research Articles

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Capacitive Deionization for the Removal of Paraquat Herbicide from Aqueous Solution
(Hindawi, 2021-10-08) Alfredy, Tusekile; Elisadiki, Joyce; Jande, Yusufu
In 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.
Capacitive deionization for water desalination using Na3Fe2(PO4)3/activated carbon composite electrodes
(Elsevier, 2025-05-28) Sufiani, Omari; Alfredy, Tusekile; Tanaka, Hideki; Teshima, Katsuya; Machunda, Revocatus; Jande, Yusufu
Water desalination technologies are attracting growing global attention as critical solutions to address water scarcity torturing mankind worldwide. Capacitive deionization (CDI) is an emerging desalination technology that offers multiple advantages, including low voltage operation and diverse material options for electrode synthesis. In this work the Na3Fe2(PO4)3 (NFP) is composited with the activated carbon (AC) to synthesize AC/NFP composites and tested in water desalination. The characterization results from several techniques reveal the successful composite synthesis. When tested in CDI experiments for brackish water desalination much higher salt removal capacity of around 22.0 was attained by AC/NFP 1:2 compared with 18.65 mg/g of AC electrode. Also, the synthesized AC/NFP 1:2 retain satisfactorily performance efficiency when cycled for twenty runs. However, owing to low resistance at the electrode-electrolyte interface the AC is more energy efficient as it exhibits much low energy consumption of about 0.056 kWh/m3 compared with the AC/NFP 1:2 cell attained 0.15 kWh/m3. This study reveals a trade-off between performance and efficiency: while the AC/NFP 1:2 cell exhibits higher salt removal capacity, it consumes significantly more energy than the AC electrode, which demonstrate superior energy efficiency.
Capacitive deionization: a promising technology for water defluoridation: a review
(IWA Publishing, 2021-08-30) Alfredy, Tusekile; Elisadiki, Joyce; Jande, Yusufu
Capacitive 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 sum marizes 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 pos sess 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 defluor idation, the discovery of actual practical use of the electrode materials for defluoridation for commercial scale
Electrosorption of paraquat pesticide on activated carbon modified by aluminium oxide (Al2O3) with capacitive deionization
(Elsevier, 2024-03-01) Alfredy, Tusekile; Elisadiki, Joyce; Dahbi, Mouad; King'ondu, Cecil; Jande, Yusufu
Composite 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.
Hermetia illucens pupae casings and biogas slurry activated carbon electrodes for Cd2 + removal from aqueous solutions using capacitive deionization
(Elsevier, 2025-04-01) Panja, Eva; Alfredy, Tusekile; Elisadiki, Joyce; Jande, Yusufu
This study examined capacitive deionisation’s effectiveness for recovering Cd2+ from water using novel carbon-based electrodes derived from Hermetia illucens pupae casings (PC) and biogas slurry (BG). Activated carbon (AC) was produced through carbonization at 500 °C and chemical activation (KOH) at 700 °C. The Brunauer-Emmett-Teller method, Scanning Electron Microscope, X-ray diffractometer, Fourier transform infrared, X-ray photoelectron spectroscopy, Raman spectroscopy, and contact angle measurement were performed on AC. Electrochemical impedance spectroscopy and cyclic voltammetry were used to test the electrochemical properties of carbons. Prepared AC possessed high specific surface areas of 549 m2/g and 927 m2/g for pupae casings and biogas slurry. Electrochemical tests revealed that PC-700 has a high specific capacitance of 271.9 Fg−1 and 105.8 Fg−1 for BG-700. Two concentrations of CdCl2 (5 mg/L and 10 mg/L) were used in a batch mode for the CDI test. Electrodes show an impressive cadmium removal efficiency of approximately 91 % and 56 % for PC and BG electrodes, respectively. Electro-sorption capacity was 10.9 mgg−1 and 2.1 mgg−1 for PC and BG electrodes, respectively. This work demonstrates the potential of PC-derived electrodes in CDI technology for recovering heavy metals from water.
Naturally occurring metal oxides from rocks as capacitive deionization electrode material for antibacterial activities
(Elsevier, 2023-05) Alphonce, Furaha; Alfredy, Tusekile; Hilonga, Askwar; Jande, Yusufu
The present study aimed to investigate the efficacy of activated carbon (AC) electrode embedded with naturally occurring metal oxides (MO) from rocks for antibacterial activities against both gram- negative (Escherichia coli) and gram-positive (Salmonella aureus) bacteria using capacitive deionization technique. The desalination and disinfection performance of the fabricated AC/MO electrode was evaluated through the batch mode experiments conducted at a potential difference of 1.2 V for 240 min (4 h). The results revealed that the AC/MO electrode achieved a complete removal efficiency of 100% for E. coli and 60% for S. aureus in the field water collected from Nduruma stream (natural water). The bacterial removal mechanism was attributed to the capacitive deionization (CDI) process and physical adsorption. The study highlights the potential of AC/MO electrode material as an effective antibacterial agent for the CDI process, which may have significant implications for the development of new technologies for water purification and disinfection.
Water defluoridation using Al/Fe/Ti ternary metal oxide-loaded activated carbon by capacitive deionization
(Royal Society of Chemistry, 2023-01-26) Alfredy, Tusekile; Elisadiki, Joyce; Kim, Young-Deuk; Jande, Yusufu
Capacitive deionization (CDI) is an environmentally friendly water treatment technology with low energy consumption. For a long time, activated carbon has been a preferred electrode material for CDI owing to its availability, easy preparation, low cost, and tunable textural properties. However, an unmodified carbon electrode does not significantly prefer anions, leading to unnecessary energy consumption for treating fluoridated water. Therefore, in this study, activated carbon materials loaded with trimetallic oxides (Al/Fe/Ti) at different mass ratios were prepared by a co-precipitation method in a temperature range between 23 and 27 °C to improve fluoride ion (F−) selectivity. The as-prepared composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy analysis. The process parameters were investigated and optimized based on experimental data using the response surface methodology (Box–Behnken design). In competitive F− removal CDI experiments, the F− concentration was reduced from 5.15 mg L−1 to 1.18 mg L−1, below the allowable limit of 1.5 mg L−1 set by the World Health Organization. The metal oxide-modified activated carbon surface (AC–Al4Fe2.5Ti4) showed significantly improved electrochemical properties and enhanced capacitance compared to the unmodified one. The modified electrode material also showed the advantages of high removal efficiency and excellent regeneration performance after continuous electric adsorption–desorption cycles. Therefore, activated carbon–Al4Fe2.5Ti4 is a potential CDI electrode material for water defluoridation applications.

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