Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 8Citation - Scopus: 7Delignification of Corncob by Choline Chloride-Urea Deep Eutectic Solvent for Enzymatic Production of Xylooligosaccharides(Elsevier B.V., 2024) Yanak,S.; Buyukkileci,A.O.Deep eutectic solvent (DES) pretreatment was applied to corncob to obtain xylooligosaccharides (XOS) by enzymatic hydrolysis using xylanase. Based on the XOS titers in the hydrolysate, urea was the most effective among the hydrogen bond donors tested to couple choline chloride (ChCl). DES pretreatment at 130 °C for two hours with ChCl-Urea (molar ratio of 1:2) containing 40 % water, decreased lignin fraction from 12.8 % to 6.9 %, while 79 % of the xylan was retained in the pretreated corncob. The highest XOS production was obtained using 400 U/g xylanase at 60 °C, which yielded 12.0 g/L XOS with a low degree of polymerization (LDP-XOS). The total XOS yield based on the raw corncob was calculated as 14.4 %, 90 % of which was LDP-XOS. The cellulose-rich residual biomass could be hydrolyzed enzymatically to glucose with 65 % cellulose digestibility. The discarded biomass after hydrolyzes was 21.7 % of the raw material. The results showed that DES was a promising pretreatment for enhancing enzymatic XOS production. © 2024 Elsevier B.V.Article Citation - WoS: 9Citation - Scopus: 10Investigation of Reactive Extraction of Monocarboxylic Acids With Menthol-Based Hydrophobic Deep Eutectic Solvent by Response Surface Methodology(Taylor & Francis Inc, 2023) Yıldız, Esra; Lalikoğlu, Melisa; Aşçı, Yavuz Selim; Sırma Tarım, BurcuThe growing demand for producing organic acids by fermentative techniques has increased the significance of separating carboxylic acids from their fermentation broth with the reactive extraction process. Considering the environmental impacts, deep eutectic solvents can be considered as a potential green alternative for the replacement of volatile organic solvents commonly used in the extraction process. In this study, a new type of green solvent named hydrophobic deep eutectic solvent (HDES) based on decanoic acid as a hydrogen bond acceptor and menthol as a hydrogen bond donor was utilized for the reactive extraction of formic, acetic, and propionic acids from their aqueous solutions. The effect of initial acid concentration, HDES molar ratio, and tri-n-octyl amine (TOA) concentration on extraction efficiency was investigated. Modeling of the reactive extraction process was performed via a response surface methodology with a central composite design. Herein, the effect of the parameters of TOA concentration, HDES molar ratio, and initial acid concentration on the distribution coefficient was investigated. According to the results, it was reported that the most effective parameter on the extraction efficiency (%E) was the amount of extractant. The results of the experimental studies showed that the highest separation efficiency was obtained for 5% initial concentrations of formic, acetic, and propionic acids by using a mixture of 0.5 HDES molar ratio solvent and 1.9 mol/L TOA. The extraction efficiencies of these acids were found to be 88.71, 92.52, and 95.90 with +/- 0.1 standard deviation, respectively.Article Citation - WoS: 23Citation - Scopus: 27Use of Deep Eutectic Solvents in the Enzyme Catalysed Production of Ethyl Lactate(Elsevier, 2019) Arıkaya, Azime; Ünlü, Ayşe Ezgi; Takaç, SerpilThe use of deep eutectic solvents (DESs) in the lipase-catalysed esterification of lactic acid with ethanol was explored by screening several DESs. Choline chloride:glycerol (1:2) was the most effective DES and provided 28.7% yield of ethyl lactate under the following conditions: 10% (v/v) of water content in DES, 3 M of initial lactic acid concentration, 5 M of initial ethanol concentration, 30 mg/mL of enzyme concentration, 50 degrees C temperature and 200 rpm agitation rate. Individual and combined effects of the reaction medium components on the enzyme activity were investigated and it was discovered that DES stimulated the enzyme activity while reactants inhibited it. A kinetic model that obeys the Ping-Pong Bi-Bi mechanism with ethanol inhibition was suggested. The kinetics parameters were determined as r(max) = 0.401 mol/L h, the Michaelis constants K-A = 1.657 mol/L and K-B = 0.799 mol/L, the inhibition constant K-iB = 0.156 mol/L. The model reasonably predicted the experimental data. The activation energy was found to be 43.28 kJ/mol. Mass transfer limitations in the reaction medium were negligible. The results are promising for further studies that will research on the use of green solvents in enzyme catalysed lactic acid esterification reactions.Article Citation - WoS: 11Citation - Scopus: 13Remarkable Effects of Deep Eutectic Solvents on the Esterification of Lactic Acid With Ethanol Over Amberlyst-15(Springer, 2020) Ünlü, Ayşe Ezgi; Arıkaya, Azime; Altundağ, Aybike; Takaç, SerpilDeep eutectic solvents (DESs) are widely used in numerous reactions both as a solvent and a catalyst. In this study, different types of DESs were investigated as a supplementary component for Amberlyst-15 to enhance its catalytic activity in the esterification reaction of lactic acid with ethanol. The effects of the following parameters such as DES type, choline chloride : glycerol (ChCl-Gly) (1 : 2) amount, molar ratio of reactants, temperature and agitation rate on the initial rate of reaction and yield of ethyl lactate were investigated. According to the results, DESs alone did not have any catalytic effect on the esterification; however, DESs together with Amberlyst-15 provided a significant increase in the initial rate of reaction and yield. The activation energy of the reaction decreased significantly with the combined use of Amberlyst-15 and ChCl-Gly (1 : 2). Internal and external mass transfer limitations were found to be negligible under optimum reaction conditions.