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RISS 인기검색어
- 검색키워드
- 저자 : Selin Şahin (검색결과 5 건)
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Selin Şahin 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.5
Solvent-free microwave extraction (SFME) of polyphenols and flavonoids from mandarin (Citrus deliciosa Tenore) leaves was investigated. A face central composite design (FCCD) through response surface methodology (RSM) was applied to study the effects of extraction time (30-90 sec), microwave irradiation power (250-350 W) and solid mass (2.5-7.5 g), and to optimize the extraction process. The optimum conditions were: extraction time, 53.155 sec; microwave power, 339.190W; and solid mass, 2.500 g. Under the optimum conditions, 0.8610mg-GAE/g-DL of total phenolic content (TPC) and 0.2440mg-CE/g-DL of total flavonoid content (TFC) were extracted. The antioxidant activity of the extracts was assessed by cupric ion reducing antioxidant capacity (CUPRAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) methods, respectively. Antioxidant values were expressed as mg trolox equivalent antioxidant capacity per gram of dried leaf (mg- TEAC/g-DL). CUPRAC values were highly correlated with both TPC and TFC (r=0.9282/0.8842, P=0.05) in the extracts, whilst DPPH (r=0.7717/0.7435, P=0.05) and ABTS (r=0.6814/0.7072, P=0.05) were relatively less correlated with the same responses.
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Comparative study of modeling the stability improvement of sunflower oil with olive leaf extract
Selin Şahin,Ezgi Sayim,Ruya Samli 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8
Commercially available sunflower oil was enriched in polyphenols by adding olive leaf extract. After extracting the dried and ground olive leaves with the assistance of homogenizer, total phenolic content (TPC) and oleuropein concentration of the extract were determined. The dried extract was partially dissolved into the sunflower oil to increase the quality and shelf-life of the oil enriched by the substances in the plants by means of solid-liquid extraction method. A face central composite design (FCCD) through response surface methodology (RSM) was used to investigate the effects of enrichment conditions (extract content, time and mixing speed) on the responses, TPC and oleuropein concentration of the enriched sunflower oil as well as to design of experiments, to model and to optimize the process. The enriched sunflower oil obtained at optimum conditions was evaluated in terms of its TPC, oleuropein, total carotenoid content (TCC), antioxidant activity (AA), peroxide value (PV) and induction time (IT), depending on those of the crude oil. Furthermore, artificial neural networks (ANN) were also employed to compare the predicted results of RSM.
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Ebru Kurtulbaş,Şahin Selin,Mehmet Bilgin,Şahika Sena Bayazit 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.3
Pharmaceutical pollution in water is the major cause of antibiotic resistance, so remediation of water from pharmaceuticals is a very important issue. Different methods are used for this purpose, with adsorption as one of the most preferred. Different adsorbents have been used for water treatment processes. Metal-organic frameworks that have highly porous structures have gained attention in the last decades. In this study, novel chromium fumarate (Cr- Fum) was prepared, and the efficiency of Cr-Fum was tested by ciprofloxacin (CPX) adsorption. Cr-Fum was prepared under reflux and characterized by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA), and differential scanning calorimetry (DSC). The general approach of the process was monolayer adsorption at low temperature and heterogeneous adsorption at high temperature. 2.5mg of adsorbent was adsorbed 4.97mg/g and 11.47% of CPX. 10mg of Cr-Fum was adsorbed 0.82mg/g and 7.27% of CPX. Partition coefficients were calculated and 0.07mg/g/M was found at 298 K. The reaction followed pseudo-first- and pseudo-second-order kinetic models. Thermodynamic analysis showed that the reaction is spontaneous and exothermic. Additional ions caused decreasing CPX adsorption, but this study showed that Cr- Fum has NaCl adsorption capacity. In future studies, NaCl adsorption should be investigated. Desorption studies were applied to Cr-Fum after the adsorption processes. 0.1M NaOH and phosphate buffer (pH=7.4) solution were used as desorption eluents. The desorption period was chosen as 6 h. NaOH solution desorbed 67.38% of CPX at first cycle and buffer solution desorbed 26.87% of CPX at second cycle.
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Fulya Taktak,Zeynep İlbay,Selin Şahin 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.9
A new type of polymer composite hydrogel was prepared by introducing activated carbons from pomegranate husk into poly ((2-dimethylamino) ethyl methacrylate) network. The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solution was studied with respect to pH of the media, initial 2,4-D concentration and activated carbon content into the polymeric network. Face centered composite design (FCCD) through response surface methodology (RSM) was used for designing the experiments as well as for studying the effects of the process parameters. A quadratic model and a two factor interaction design model were developed for the removal of 2,4-D and adsorption capacity, respectively. The optimum pH of the pesticide solution, activated carbon content into the polymeric network and initial concentration of 2,4-D were found as 3, 2.5 wt% and 100mg/L. 63.245% and 68.805 (mg/g) for the removal of 2,4-D and adsorption capacity were obtained by using Simplex optimization method. Furthermore, the surface characteristics of the adsorbent prepared under optimized conditions were examined by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR).
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Sibel Yazar,Ebru Kurtulbaş,Sinem Ortaboy,Gülten Atun,Selin Şahin 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.7
Olive leaves were extracted with homogenizer-assisted extraction (HAE). Box-Behnken (BBN) design was employed through response surface approach (RSA) to achieve the optimum conditions. Bioactivity of the extract was assessed by its oleuropein, total biophenol (TBC) and total flavonoid (TFC) content along with its antioxidant activity determined by DPPH and CUPRAC assays. A new nanocomposite was developed using reduced graphene oxide (rGO) modified with TiOx (Ti-rGO) for trace amount determination of oleuropein in olive leaf extract. Structural characterization of the electrode was clarified using atomic force microscopy (AFM) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) techniques. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were performed to investigate electrochemical behavior of oleuropein using three electrode configurations. Results of CV and SWV showed that quasi-reversible reaction occurred on electrode/electrolyte interface and a linear concentration range of 5-30 nM was obtained with a detection limit of 0.57 nM for oleuropein.
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