Chemical Engineering / Kimya Mühendisliği
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Article Mini modular plant design for ethylene production using Martian atmosphere on Mars(Elsevier, 2024) Deliismail, Özgün; Şeker, ErolA main shift in the competitive landscape of technology development is in 3D printing of complex articles made of variety of materials due to faster manufacturing and less human error in the production. In fact, it seems to be a viable candidate for the construction of structures for terrestrial and extraterrestrial life in future. Thus, new or damaged equipment in space explorations could be replaced instantly, and habitats could be manufactured using 3D printing in varying gravitational fields in the solar system. Among 3D printing materials, HDPE is commonly used in the projects, such as a prototype manufacturing or pipes or damp-proof membrane. This study initially focused on the preliminary design of the self-sustaining mini ethylene production plant from Martian atmosphere with scale-out architecture. UniSIM® was integrated with MATLAB® via CAPE-OPEN extension to design mini-ethylene production plant at low gravity. Ethylene capacity was found as 17.71 tons/year for 100 modules. © 2023 COSPARArticle Citation - WoS: 4Citation - Scopus: 5Breakthrough Curve Analysis of Phosphorylated Hazelnut Shell Waste in Column Operation for Continuous Harvesting of Lithium From Water(Elsevier, 2024) Recepoğlu, Yaşar Kemal; Arar, Ozguer; Yuksel, AsliIn batch-scale operations, biosorption employing phosphorylated hazelnut shell waste (FHS) revealed excellent lithium removal and recovery efficiency. Scaling up and implementing packed bed column systems necessitates further design and performance optimization. Lithium biosorption via FHS was investigated utilizing a continuous-flow packed-bed column operated under various flow rates and bed heights to remove Li to ultra-low levels and recover it. The Li biosorption capacity of the FHS column was unaffected by the bed height, however, when the flow rate was increased, the capacity of the FHS column decreased. The breakthrough time, exhaustion time, and uptake capacity of the column bed increased with increasing column bed height, whereas they decreased with increasing influent flow rate. At flow rates of 0.25, 0.5, and 1.0 mL/min, bed volumes (BVs, mL solution/mL biosorbent) at the breakthrough point were found to be 477, 369, and 347, respectively, with the required BVs for total saturation point of 941, 911, and 829, while the total capacity was calculated as 22.29, 20.07, and 17.69 mg Li/g sorbent. In the 1.0, 1.5, and 2.0 cm height columns filled with FHS, the breakthrough times were 282, 366, and 433 min, respectively, whereas the periods required for saturation were 781, 897, and 1033 min. The three conventional breakthrough models of the Thomas, Yoon-Nelson, and Modified Dose-Response (MDR) were used to properly estimate the whole breakthrough behavior of the FHS column and the characteristic model parameters. Li's extremely favorable separation utilizing FHS was evidenced by the steep S-shape of the breakthrough curves for both parameters flow rate and bed height. The reusability of FHS was demonstrated by operating the packed bed column in multi-cycle mode, with no appreciable loss in column performance.Article Citation - WoS: 7Citation - Scopus: 7Synthesis and Characterization of Single-Walled Carbon Nanotube: Cyto-Genotoxicity in Allium Cepa Root Tips and Molecular Docking Studies(Wiley, 2022) İnce Yardımcı, Atike; İstifli, Erman Salih; Açıkbaş, Yaser; Liman, Recep; Yağmurcukardeş, Nesli; Yılmaz, Selahattin; Ciğerci, İbrahim HakkıHerein, single-walled carbon nanotubes (SWCNTs) were synthesized by the thermal chemical vapor deposition (CVD) method, and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Raman spectroscopy, dynamic light scattering (DLS), and thermo-gravimetric analysis (TGA). The results indicated that obtained nanotubes were SWCNTs with high crystallinity and their average diameter was 10.15 ± 3 nm. Allium cepa ana–telophase and comet assays on the root meristem were employed to evaluate the cytotoxic and genotoxic effects of SWCNTs by examining mitotic phases, mitotic index (MI), chromosomal aberrations (CAs), and DNA damage. A. cepa root tip cells were exposed to SWCNTs at concentrations of 12.5, 25, 50, and 100 μg/ml for 4 h. Distilled water and methyl methanesulfonate (MMS, 10 μg/ml) were used as the negative and positive control groups, respectively. It was observed that MIs decreased statistically significantly for all applied doses. Besides, CAs such as chromosome laggards, disturbed anaphase–telophase, stickiness and bridges and also DNA damage increased in the presence of SWCNTs in a concentration-dependent manner. In the molecular docking study, the SWCNT were found to be a strong DNA major groove binder showing an energetically very favorable binding free energy of −21.27 kcal/mol. Furthermore, the SWCNT interacted effectively with the nucleotides on both strands of DNA primarily via hydrophobic π and electrostatic interactions. As a result, cytotoxic and genotoxic effects of SWCNTs in A. cepa root meristematic cells which is a reliable system for assessment of nanoparticle toxicology were demonstrated in this study.Article Citation - Scopus: 8Biofuel Production From Nannochloropsis Oculata Microalgae in Seawater Without Harvesting and Dewatering Over Alumina-Silicate Supported Nickel Catalysts(Elsevier, 2018) Deliismail, Özgün; Özdoğru, Bertan; Şeker, ErolThe aim of this work was to study the production of biofuels from marine Nannochloropsis oculata without harvesting and dewatering over the single step sol-gel made alumina-silicate supported nickel catalysts at 80 °C and 1.0 atm. Sulfuric acid, hydrochloric acid, and nitric acid were used in the sol-gel to study the effect of acid type on catalyst activities. The catalyst made using sulfuric acid resulted in 74% microalgae conversion as compared to the catalysts made with other acids. Treatment of this catalyst with ~35 g of NaCl per kg of water at 80 °C and 1.0 atm for 24 h increased microalgae conversion to 91.5% under the same reaction condition and the bio-fuels ranging from mono/polysaccharides, polyols to esters and fatty acids were produced. This study showed that nickel and 25.1 ?mol/g of total acidity and acidic strength having 130–380 °C of temperature range was necessary to achieve 91.5% conversion. © 2018 Elsevier LtdArticle Citation - WoS: 29Citation - Scopus: 35Sustainable Bio-Nano Composite Coatings for the Protection of Marble Surfaces(Elsevier Masson SAS, 2015) Ocak, Y.; Sofuoglu, A.; Tihminlioglu, F.; Böke, H.Water repellency on natural stone surfaces is the most important issue in the protection of stone monuments from effects of atmospheric pollutants. In this study, effectiveness of a bio-nano composite coating, composed of a biodegradable polymer (poly-L-lactide [PLA]) and montmorillonite clay (MMT) was investigated for the protection of marble surfaces from pollution. The clay dispersion in polymer matrices was analyzed by using Scanning Tunnel Electron Microscopy (STEM) and X-Ray Diffraction (XRD), while protection performance was investigated by the measurement of surface roughness, wettability, water vapor permeability, capillary water absorption, and color changes on the marble surfaces. As a result, no alteration on the color of coated marbles was observed, significant improvement was obtained for hydrophobicity of the surface and inhibition of sulfation reaction on the exposed marble surfaces under acidic atmosphere. It could be said that PLA based nanocomposites seem to be promising materials as protective coating agents in reducing the effects of water and atmospheric pollutants on marble surfaces. © 2014 Elsevier Masson SAS.Article Citation - WoS: 28Citation - Scopus: 31The Effects of Catalyst Pretreatment, Growth Atmosphere and Temperature on Carbon Nanotube Synthesis Using Co-mo/Mgo Catalyst(Elsevier Ltd., 2015) İnce Yardımcı, Atike; Yılmaz, Selahattin; Selamet, YusufThe growth of high quality and high yield carbon nanotubes (CNTs) by catalytic chemical vapor deposition (CVD) of CH4 over Co-Mo/MgO catalyst was investigated for different growth temperatures and H2 flow rates. It was observed that CNT yield decreased with the H2 flow rate, however, quality increased with increasing H2 flow rate. CNT yield increased for the temperatures 850-950 °C but dropped significantly above 950 °C. In this study, the highest yield of 1526% was obtained at the growth temperature of 950 °C. The optimum H2 flow rate was 200 sccm; this rate gave both high graphitization and high yield of product. Various CNT growth atmospheres including Ar, H2 and the mixture of both gases were also analyzed and it was observed that the highest quality CNTs were obtained for both pretreatment and growth carried out with H2. This gave a high yield of 292%. On the other hand, CNT growth carried out under Ar atmosphere gave higher CNT yield of 368%, however, the CNTs grown with Ar were more defective and had larger diameters. Prime novelty statement We demonstrate a sorbitol added catalysis synthesis method and importance of the ideal growth conditions to improve high quality single walled carbon nanotube yield up to 1500%.Article Citation - WoS: 15Citation - Scopus: 18Preparation and Characterization of Magnesium Stearate, Cobalt Stearate, and Copper Stearate and Their Effects on Poly(vinyl Chloride) Dehydrochlorination(John Wiley and Sons Inc., 2015) Gönen, Mehmet; Egbuchunam, Theresa Obuajulu; Balköse, Devrim; İnal, Fikret; Ülkü, SemraPreparation and characterization of pure metal soaps and investigation of their effects on poly(vinyl chloride) (PVC) dehydrochlorination were the objectives of the present study. Magnesium stearate (MgSt2), cobalt stearate (CoSt2), and copper stearate (CuSt2) were prepared by a precipitation method. An aqueous sodium stearate (NaSt) solution was mixed at 500 rpm with respective metal salt solutions at 75oC. The precipitates that formed were collected by filtration, washed with water, and ultimately dried at 105oC under reduced pressure. Lamellar crystals that melted on heating were obtained. Solid-liquid phase transitions were observed by optical microscopy at 160oC, 159oC, and 117oC for MgSt2, CoSt2, and CuSt2, respectively. However, the melting points of MgSt2, CoSt2, and CuSt2 were determined as 115oC, 159oC, and 111oC, respectively, by analysis by differential scanning calorimetry. The onset temperature of the mass loss was the lowest at 255oC for CuSt2 and the lowest activation energy for thermal decomposition was 18 kJ/mol for CuSt2. CoSt2 was effective in extending the induction time of PVC dehydrochlorination at both 140oC and 160oC. The activation energy calculated from stability time decreased from 175 kJ/mol for a blank PVC sample to 114, 105, and 107 kJ/mol for MgSt2, CoSt2, and CuSt2-containing PVC samples, respectively. All three metal soaps accelerated the dehydrochlorination of PVC. J. VINYL ADDIT. TECHNOL., 21:235-244, 2015.Article Citation - WoS: 5Citation - Scopus: 5Methylene Blue Adsorption From Aqueous Solutions To Flexible Poly(vinyl Chloride) Silica Composites(John Wiley and Sons Inc., 2015) Yetgin, Senem; Ulutan, Sevgi; Balköse, DevrimMethylene blue (MB) adsorption studies were performed with poly(vinyl chloride)-(dioctyl phthalate)-silica composites, which were obtained by using plastisol-plastigel technology. The films were flexible, having elastic modulus of 1.0-1.5 GPa. Diminishing MB concentration in the aqueous phase was followed as the adsorption process advanced by using visible spectroscopy. Contributions of the individual components of the composites to adsorption were also investigated. Although the MB adsorption capacity was extensively high for silica, it was moderate for the composite, most likely owing to the occlusion of pores of silica by plasticizer to some extent. The improvement of MB adsorption capacity of the composites as the silica ratio increased was explicitly deduced from the optical microscopy photographs. The diffusion coefficients of MB through the composites were 5 × 10-13, 6 × 10-13, and 3 × 10-13 m2 s-1 with regression coefficients of 0.73, 0.89, and 0.88 for 0, 2, and 16% silica-containing composites, respectively. Because of the slow diffusion of MB in poly(vinyl chloride)-silica composites, using them as dynamic column adsorbent was not practical. However, these versatile plastics can be used as plastic labels, colored clothing, leather substitutes, antimicrobial medical devices, and laser printable surfaces.Article Citation - WoS: 44Citation - Scopus: 44Chitosan-Polyoxometalate Nanocomposites: Synthesis, Characterization and Application as Antimicrobial Agents(Springer Verlag, 2014) Fiorani, Giulia; Saoncella, Omar; Kaner, P.; Alsoy Altınkaya, Sacide; Figoli, Alberto; Bonchio, Marcella; Carraro, MauroPolyoxometalates (POMs) were used, together with chitosan (CS), to obtain hybrid nanoaggregates. Three representative POMs were efficiently assembled into nanoparticles of few hundred nm diameter, featuring entangled ribbons substructure. In order to establish suitable preparation and stability conditions, the assemblies were characterized in solution by UV-Vis spectroscopy, dynamic light scattering and ζ-potential. The nanoparticles were tested against E. coli (106 CFU/ml) in aqueous solution, showing a synergic activity of the heteropolyacid H5PMo10V2O40 and CS. For such components, a highly porous and antibacterial film was obtained upon lyophilisation of the colloidal mixture.Article Citation - WoS: 18Citation - Scopus: 21Crystallization Kinetics and Affecting Parameters on Polycaprolactone Composites With Inorganic and Organic Additives(John Wiley and Sons Inc., 2015) Cesur, Serap; Alp, Burcu; Küçükgöksel, Yelda; Kahraman, Tansel; Balköse, DevrimThe isothermal crystallization and mechanical behavior of biodegradable polycaprolactone (PCL) composites with organic (oleic acid and glycerol monooleate) and inorganic (zinc oxide, organoclay, and hydroxy apatite) additives used alone or simultaneously were investigated. The effect of all additives on the degree of crystallinity percentage (DOC%), isothermal crystallization kinetics parameters, and mechanical test results of PCL composites was studied. The PCL composite films were prepared by solvent casting by using dichloromethane as the solvent. The films were characterized by X-ray diffraction, differential scanning calorimetry (DSC), and tensile tests. DSC of the first melting and X-ray diffraction DOC% results (for composites by solvent casting) are compatible. The values by DSC of the second melting (for composites by extrusion method) are lower. Organoclay gives the highest crystallinity among the other inorganic additives used. Small amounts of inorganic additives act as a nucleating agent and increase the crystallinity; the higher amounts decrease. The organic additives act as the plasticizer. When used alone, it lowers the crystallinity, but when used with inorganic additives, it improves the dispersion of inorganic particles in the polymer matrix. The isothermal crystallization kinetics parameters by Avrami analysis showed that crystallization was controlled by nucleation and the crystals had spherical structure. The nucleation type changed between thermal and athermal nucleation. The Pukanzky model interaction parameter B indicated that the organic additives improved the dispersion of inorganic particles in the polymer matrix. Statistically significant, eight correlations (F>6) were obtained for the crystallinity, crystallization parameters, Young's modulus, and tensile strength as a function of concentration of additives.