Browsing by Author "Chung, Yu-Ta"

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Detoxification of nicotine solution using Fe-0-based processes: Toxicity evaluation by Daphnia magna neonate and embryo assays
(2018-01-01)
Chen, Kuei-Fang
;
Huang, Sin-Yi
;
Chung, Yu-Ta
;
Wang, Kai-Sung
;
Wang, Chih-Kai
Three Fe-0-based techniques were used to treat wastewater containing nicotine. Daphnia magna neonates and embryos were used in bioassays to evaluate the toxicity of nicotine before and after the treatments. The results show that nicotine was highly toxic to Daphnia neonates (EC50, 48h = 0.379 mg L-1, EC50, 72h = 0.125 mg L-1). Although nicotine was moderately toxic to Daphnia embryos after a 48 h exposure (EC50, 48h = 250.8 mg L-1), nicotine was highly toxic to the embryos (EC50, 72h = 1.328 mg L-1) when exposure time was extended to 72 h. Nicotine induced malformations in the second antenna, carapace, and tail spine. The Fe-0/air process was unable to effectively degrade nicotine. In contrast, the Fe-0/H2O2 process and micro-electrolysis efficiently removed nicotine within 30 min (90.8% and 94.6%, respectively). The chemical oxygen demand removed by microelectrolysis (70.4%) was clearly higher than that removed by the Fe-0/H2O2 technique (58.1%). Micro-electrolysis maintained its effectiveness (> 81.3%) after seven reuse cycles. A spectral analysis indicated that the micro-electrolysis process effectively removed the pyridine (A(260)) and pyrrolidine rings (A(206)) of nicotine. The toxicity of Fe-0/H2O2-and micro-electrolysis-treated solutions were low (3.75% embryo mortality rate after 72 h). The above results show that micro-electrolysis is a potential approach to remove nicotine from solution.
Facile modification of graphite sheet by novel electrochemical exfoliation/oxidant method and its adsorption of caffeine from water
(2017-11-01)
Chung, Yu-Ta
;
Wang, Chih-Kai
;
Wang, Kai-Sung
;
Huang, Sin-Yi
;
Chang, Shih-Hsien
Graphite is an abundant natural material, but its specific area and adsorptive ability are low. In this study, a graphite sheet modified by an electrochemical exfoliation/oxidant process (G(SEEO-modified)) was used as an adsorbent to remove caffeine from solution. Experimental results indicate that G(SEEO-modified) effectively adsorbs caffeine and that the adsorptive ability of GSEEo-modified Prepared with KMnO4 is obviously higher than that of G(SEEO-modified) Prepared with H2O2 or S2O82-. The optimal preparation conditions for G(SEEO-modified) were 1.2 M H2SO4, 0.1 M KMno(4), 80 degrees C, and an applied voltage of 4 V. G(SEEO-modified) of 4.0 g L-1 efficiently adsorbed 95% of the caffeine (Co = 50 mg L-1) within 30 min. Langmuir isotherms describe the adsorption behavior well (q(max) = 1000 mg L-1, b = 0.001, R-2 = 0.9912). Additionally, 0.1 M acetone effectively regenerated exhausted G(SEEO-modified), which maintained a high adsorptive ability (81%) after seven cycles of adsorption-regeneration treatment. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.