Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 4Citation - Scopus: 4Polymer-Bonded Cdte Quantum Dot-Nitroxide Radical Nanoprobes for Fluorescent Sensors(Springer, 2022) Karabıyık, Merve; Ebil, ÖzgençA novel functional polymer-bonded quantum dots (QDs)-nitroxide radical complex was demonstrated. In the first part of the study, the synthesis of polymer thin films via initiated chemical vapor deposition (iCVD), functionalization of polymer thin films with amine functional groups, and attachment of QDs to polymer surface were demonstrated. Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy together with fluorescence spectroscopy studies revealed that aliphatic primary amine (propylamine) was very effective for the functionalization of iCVD deposited poly(glycidyl methacrylate) (pGMA) and its copolymer with diethylaminoethyl methacrylate (p(GMA-co-DEAEMA)) and also QD attachment to functionalized polymer surface. In the second part of the study, the synthesis and attachment of Quantum Dot-4Amino TEMPO (QD-4AT) nanoprobes to functionalized pGMA thin films and feasibility of using them as fluorescent sensor structures were investigated. It was found that high initial 4AT concentration and long (24 h) interaction times are beneficial for nanoprobe synthesis. Electron paramagnetic resonance (EPR) spectroscopy analysis revealed the existence of covalent bond between QD and 4AT when 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide was used during synthesis. EPR analysis together with fluorescence microscopy investigation confirmed the successful attachment of nanoprobes to polymer surface. Time-depended fluorescence quenching analysis revealed that more than 50% reduction in fluorescence intensity within 15 min demonstrating the potential of polymer bonded QD-4AT nanoprobes in various sensor applications.Article Citation - WoS: 10Citation - Scopus: 12Enhanced Model Protein Adsorption of Nanoparticulate Hydroxyapatite Thin Films on Silk Sericin and Fibroin Surfaces(Springer, 2022) Özcan, Selçuk; Çiftçioğlu, MuhsinHydroxyapatite coated metallic implants favorably combine the required biocompatibility with the mechanical properties. As an alternative to the industrial coating method of plasma spraying with inherently potential deleterious effects, sol-gel methods have attracted much attention. In this study, the effects of intermediate silk fibroin and silk sericin layers on the protein adsorption capacity of hydroxyapatite films formed by a particulate sol-gel method were determined experimentally. The preparation of the layered silk protein/hydroxyapatite structures on glass substrates, and the effects of the underlying silk proteins on the topography of the hydroxyapatite coatings were described. The topography of the hydroxyapatite layer fabricated on the silk sericin was such that the hydroxyapatite particles were oriented forming an oriented crystalline surface. The model protein (bovine serum albumin) adsorption increased to 2.62 µg/cm2 on the latter surface as compared to 1.37 µg/cm2 of hydroxyapatite on glass without an intermediate silk sericin layer. [Figure not available: see fulltext.].Article Citation - WoS: 13Citation - Scopus: 11Valorization of Olive Tree Pruning Waste for Potential Utilization in Lithium Recovery From Aqueous Solutions(Springer, 2022) Nampeera, Jackline; Recepoğlu, Yaşar Kemal; Yüksel, AslıOlive tree pruning waste, mainly composed of olive branches, was converted into a value-added and sustainable product capable of lithium as a biosorbent through alkali treatment and phosphorylation reaction. Characterization studies were performed by SEM–EDX, XPS, FTIR, and TGA. Factors affecting biosorption mechanism, i.e., sorbent dosage, pH, initial Li+ concentration and temperature, and competitive ions’ presence, were investigated the synthesized functionalized olive branches (FOB). A commercial lithium selective resin, Lewatit TP 260, was also compared with FOB in batch and column studies. The Freundlich model fits adsorption isotherms better than the Langmuir model, with a maximum adsorption capacity of 6.7 mg/g at 30 °C and pH 7–8. Kinetic studies proved fast kinetics and equilibrium were attained in 6 min, while thermodynamic studies showed an exothermic (Δ Ho= - 17.52 kJ/ mol) , spontaneous reaction Δ Go< 0 at all temperatures), and increased randomness Δ So= + 24.27 J/ mol. K) at the interaction interface. Column studies revealed that although Lewatit TP 260 resin showed higher sorption capacity, its desorption efficiency (50.42%) was lower than that of FOB (99.9%), and the degree of column utilization of FOB (56.81%) was better than Lewatit TP 260 resin’s (16.0%). The findings were encouraging in the successful synthesis of a promising biosorbent from an abundant waste in Turkey for use in sustainable lithium recovery from aqueous sources. Graphical abstract: [Figure not available: see fulltext.]Article Citation - WoS: 7Citation - Scopus: 7Modification of Grape Pulp With Citric Acid for the Production of Natural Ion Exchanger Resin and Removal of Pb (ii) and Cd (ii) From Aqueous Solutions: Kinetic, Thermodynamics, and Mechanism(Springer, 2021) Arslanoğlu, Esra; Eren, Muhammet Ş. A.; Arslanoğlu, Hasan; Çiftçi, HarunIn this study, grape pulp (MGP) modified with NaOH and citric acid was used in the production of natural ion exchangers. The effects of parameters such as initial pH, MGP dosage, temperature, initial metal ion concentration, and contact time on the removal of Pb (II) and Cd (II) ions from aqueous solutions using modified materials were investigated by batch experiments. It was found that the experimental kinetic data fit the second-order model, and the activation energy for Pb (II) and Cd (II) adsorption processes were 20.68 and 38.61 kj mol(-1), respectively. Although the initial adsorption rate increases with increasing temperature, the adsorption efficiency slightly decreases. It was calculated that the equilibrium data fit the Langmuir isotherm better, and the maximum adsorption capacities for Pb (II) and Cd (II) adsorption processes were approximately 1.496 and 1.022 mmol g(-1) at 25 degrees C, respectively. Thermodynamic analysis has shown that the adsorption processes of Pb (II) and Cd (II) are exothermic (Delta H degrees(Pb) = -35.68 kj mol(-1), Delta H degrees(Cd) = -21.19 kj mol(-1)) and have a self-developing character.Article Citation - WoS: 15Citation - Scopus: 17Fabrication, Characterization, and Adsorption Applications of Low-Cost Hybride Activated Carbons From Peanut Shell-Vinasse Mixtures by One-Step Pyrolysis(Springer, 2021) Arslanoğlu, Esra; Eren, Muhammet Şakir Abdullah; Arslanoğlu, Hasan; Çiftçi, HarunThe present work aims to develop an innovative, alternative, fast, and cost-effective one-step pyrolysis method for activated carbon production using peanut shell and vinasse mixture. This facile procedure is based on single-step carbonization treatment at a temperature range of 400-800 degrees C. Different carbonization time (15-360 min), impregnation ratio (1-3 g/g), impregnation time (3-24 h), and nitrogen flow rate (300 and 600 ml/min) were examined. The chemical and physical properties of the activated carbon examined by SEM-EDX, FT-IR analysis, particle size distribution, iodine number, pH(zpc), BET surface area, and surface functional group analysis by Boehm's titration. The results illustrate that the values of BET surface area, total pore volume, average pore diameter, iodine number, pH(zpc), and carbon content of activated carbon were found as 1290.5 m(2)/g, 0.5667 cm(3)/g, 21.2 angstrom, 1258.4 mg/g, 5.7, and 86.89%, respectively.Article Citation - WoS: 13Citation - Scopus: 14Robust Fluorinated Siloxane Copolymers Via Initiated Chemical Vapor Deposition for Corrosion Protection(Springer, 2021) Cihanoğlu, Gizem; Ebil, ÖzgençHomopolymers of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4), 2-(perfluorohexyl)ethyl acrylate (PFHEA) and 2-(perfluoroalkyl)ethyl methacrylate (PFEMA) and their copolymers were synthesized via initiated chemical vapor deposition (iCVD). All coatings exhibited excellent adhesion to substrates. The corrosion resistance of iCVD coatings was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. In addition, chemical durability of various organic solvents and adhesion to the substrate were also evaluated. Tafel polarization measurements in 5 wt% NaCl solution revealed that the corrosion rates as low as 0.002 mpy on zinc substrates can be reached with 250-nm-thick iCVD-synthesized polymers which is lower than previously reported polymer coatings and more than three orders of magnitude lower than bare zinc. EIS analysis coupled with equivalent electric circuits model confirmed that poly(V4D4) and poly(PFHEA) homopolymers show extremely high protection efficiencies (similar to 99%) on zinc, while poly(V4D4-co-PFHEA) copolymer with slightly lower corrosion efficiency (85-91%) provides a better anticorrosion barrier with weight loss reduction by 57 and 45% for copper and zinc, respectively, and with improved chemical and mechanical properties. The results indicate that iCVD process enables fabrication of finely tuned fluorinated siloxane copolymer conformal coatings for corrosion protection on a variety of substrates.Conference Object Investigation of Therapeutic Effects of Doxorubicin Loaded Microbubbles in In-Vivo Breast Cancer Model(Springer, 2017) Serinan, Efe Özgür; Barış, Mustafa; Kürkçü, Gülşah; Önercan, Cansu; Çalışır, Meryem; Altun, Zekiye; Aktaş, Safiye; Aydın, Melek; Kılıç Özdemir, Sevgi; Yılmaz, Osman; Özdemir, Ekrem[No abstract available]Article Citation - WoS: 32Citation - Scopus: 36A Novel Bilayer Zein/Mmt Nanocomposite Incorporated With H. Perforatum Oil for Wound Healing(Springer, 2020) Güneş, Seda; Tamburacı, Sedef; Tıhmınlıoğlu, FundaRecently, layered structures composed of nanofibers have gained attention as a novel material to mimic skin tissue in wound healing applications. The aim of this study is to develop a novel hybrid bilayer material composed of zein based composite film and nanofiber layers as a wound dressing material. The upper layer was composed of H. perforatum oil incorporated zein film including MMT and the bottom layer was comprised of 3D electrospun zein/MMT nanofibers to induce wound healing with the controlled release of H. perforatum oil. The bilayer composites were characterized in terms of mechanical test, WVP, water uptake and surface wettability. Antimicrobial activity of the wound dressings against microorganisms were investigated by disc diffusion method. In vitro cytotoxicity of monolayer film and bilayer structure was performed using WST-1 assay on HS2 keratinocyte and 3T3 cell lines. Results indicated that the prepared monolayer films showed appropriate mechanical and gas barrier properties and surface wettability for wound healing. Controlled release of H. perforatum oil was obtained from fabricated membranes up to 48 h. Bilayer membranes showed antimicrobial activity against E. coli, S. aureus, and C. albicans and did not show any toxic effect on NIH3T3 mouse fibroblast and HS2 keratinocyte cell lines. In vitro scratch assay results indicated that H. perforatum oil had a wound healing effect by inducing fibroblast migration. The proliferation study supported these results by increasing fibroblast proliferation on H. perforatum oil loaded bilayer membranes.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.