Browsing by Author "Kim, Young-Deuk"

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Effects of different lengths and doses of raw and treated sisal fibers in the cement composite material
(nature, 2025-01-10) Fode, Tsion; Chande Jande, Yusufu; Kim, Young-Deuk; Ham, Min-Gyu; Lee, Jieun; Kivevele, Thomas; Rahbar, Nima
Sisal fiber moisture sensitivity and degradation are treated by alkaline and pozzolanic methods, such as silica fume and kaolin surface coating. However, it is novel that the treatment of sisal fiber by calcined bentonite slurry can coat sisal fiber from moisture and protect it from cement hydration by consuming free lime and reducing cement matrix alkalinity. Therefore, the present study treated sisal fibers with calcined bentonite slurry and investigated the effect of using different lengths and doses of treated and raw sisal fibers in a mortar. The results indicate that the treatment of sisal fiber with bentonite slurry improved the roughness of the fiber, reduced fresh bulk density, improved resistance in acid, salt, and alkaline conditions, and increased compressive and flexural strength at 28 and 56 days compared to the control mixture and raw sisal fiber-employed mortar. Therefore, TS1L10 improved compressive strength by 30.62% and 1.8% at 28 and 56 days, respectively. Also, TS1L10 enhanced strength and residual strength in 5% HCl by 54.54% and 72.25%, respectively, compared to the control mixture at 56 days. Generally, the present study revealed the importance of calcined bentonite-treated sisal fibers in a mortar mixture for improved durability, physical and mechanical properties.
Integrated Capacitive Deionization and Humidification-Dehumidification System for Brackish Water Desalination
(MDPI, 2021-11-15) Soomro, Sadam-Hussain; Jande, Yusufu; Memon, Salman; Kim, Woo-Seung; Kim, Young-Deuk
A hybrid capacitive deionization and humidification-dehumidification (CDI–HDH) desalination system is theoretically investigated for the desalination of brackish water. The CDI system works with two basic operations: adsorption and regeneration. During adsorption, water is desalted, and during the regeneration process the ions from electrodes are detached and flow out as wastewater, which is higher in salt concentration. This wastewater still contains water but cannot be treated again via the CDI unit because CDI cannot treat higher-salinity waters. The discarding of wastewater from CDI is not a good option, since every drop of water is precious. Therefore, CDI wastewater is treated using waste heat in a process that is less sensitive to high salt concentrations, such as humidification-dehumidification (HDH) desalination. Therefore, in this study, CDI wastewater was treated using the HDH system. Using the combined system (CDI–HDH), this study theoretically investigated brackish water of various salt concentrations and flow rates at the CDI inlet. A maximum distillate of 1079 L/day was achieved from the combined system and the highest recovery rate achieved was 24.90% from the HDH unit. Additionally, two renewable energy sources with novel ideas are recommended to power the CDI–HDH system.
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.