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RISS 인기검색어
- 검색키워드
- 저자 : Ha Vinh Hung (검색결과 2 건)
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Ha Thi Thu Vu,Hanh Thi Vinh Le,Yen Thi Hai Pham,Hung Quoc Le,Phong Hong Pham 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.3
Different kinds of materials for electrodes based on glassy carbon, carbon fibers, and modified by an ionic liquid (BMIMBF4) were used to determine 2,4,6-trinitrotoluene (TNT) in water environment by differential pulse adsorptive stripping voltammetry. The modified electrode based on BMIMBF4 showed a better performance than those based on the microelectrode and glassy carbon electrode (GCE) in term of sensitivity. The best performance was obtained with the ionic liquid-modified electrode with 80:10:10 (w/w/w) of the graphite powder/paraffin oil/BMIMBF4 composition in PBS, pH 8. The TNT concentration was linear in the range 1.5 to ~30 ppm for all studied electrodes (r = 0.9978) with a detection limit of 88.6 ppb using IL-CPE (ionic liquid-modified carbon paste electrode). This latter electrode was used to measure real samples taken from Red River, Vietnam. The recovery study for TNT in natural samples gave values from 99.7% to 103.3%. IL-CPE demonstrated long-term stability and reproducibility, with a relative standard deviation of 1.67%.
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Huynh Trung Hai,Ha Vinh Hung,Vu Minh Trang 한국자원공학회 2022 Geosystem engineering Vol.25 No.3
Rare earth elements (REEs) are recognized as one of the most critical elements and considered essential for the development of sustainable energy technologies, lasers, electronics, alloys, catalysts, and other applications. In order to meet the increasing demand to ensure those essential usages, the supply of REEs is however limited from the primary sources. Recovery of REEs from secondary resources, such as discarded electrical and electronic equipment, referred to as electronic waste (e-waste) is consequently crucial. Fluorescent lamps among such wastes are of special concern due to the high quantity of REEs present in them. This article discusses a potential hydrometallurgical method for recovering REEs (yttrium and europium) from fluorescent lamp waste via nitric acid leaching. The effects of leaching factors including acid concentration and temperature were examined. To assist the leaching yields of those metals, the effect of alkaline fusion was specifically examined. The kinetics of both processes, direct- and alkaline fusion-assisted leaching were investigated based on the shrinking core model. In the case of direct leaching, the metal dissolution was controlled by surface chemical reaction with apparent activation energies of 43.9 and 48.1 kJ/mol for yttrium and europium, respectively, in the temperature range 303–333 K. Pretreatment, viz., the alkaline fusion changed the subsequent leaching mechanism to diffusion control with apparent activation energies of 7.4 and 9.5 kJ/mol for the respective metal in the same temperature range. Optimization of the alkaline fusion-assisted acid leaching process was undertaken by applying response surface methodology (RSM) based on the central composite design (CCD). Under the alkaline fusion conditions such as soda/fluorescent powder mass ratio of 0.65 g/g, temperature of 1223 K and reaction time of 7200 s followed by acid leaching (nitric acid concentration – 3.5 M, temperature-323 K, pulp density – 30 g/L and leaching duration – 1200 s), the leaching efficiencies of 92.6% and 99.5% for yttrium and europium, respectively, could be achieved.
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