Demir, Mustafa
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Demir, Mustafa M.
Demir, Mustafa Muammer
Demir, Mustafa Muammer
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Prof. Dr.
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mdemir@iyte.edu.tr
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Malzeme Bilimi ve Mühendisliği Bölümü
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Sustainable Development Goals
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Scholarly Output
123
Articles
83
Citation Count
0
Supervised Theses
33
123 results
Scholarly Output Search Results
Now showing 1 - 10 of 123
Article Smart phone assisted detection and quantification of cyanide in drinking water by paper based sensing platform(Elsevier Science Sa, 2017) Incel, Anil; Akin, Osman; Cagir, Ali; Yildiz, Umit Hakan; Demir, Mustafa M.; Demir, MustafaAn organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD(4)TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6 mu m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN- addition from 10(-2) to 10(-12) M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN- concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions. (C) 2017 Elsevier B.V. All rights reserved.Doctoral Thesis The fabrication of plasmonic/photonic nanostructures in polymers: Mechanical sensor applications(Izmir Institute of Technology, 2019-07) Topçu, Gökhan; Demir, Mustafa; Demir, Mustafa Muammer; Eanes, MehtapFunctional polymer nanocomposites offer futuristic properties by the association of inorganic additive micro-/nanostructures into the polymers. With the growing knowledge of the physical fundamentals, stimuli-responsive polymeric composites enable detection of chemical, thermal, and mechanical changes by optical sensors and probes. Since the accurate real-time detection of the change in mechanical loading is vital for construction and industrial fields, the use of colorimetric pressure elements in a static body is important for the prediction of catastrophic failures. In this thesis, strain/pressure responsive colorimetric films were produced. A number of polymer nanocomposite-based mechanical sensors are presented. By transferring the optical activity (coherent reflection and plasmonic coupling) of the additives into various polymeric matrices having different mechanical features, the strain and pressure sensors are developed for practical applications. There are two approaches used for the fabrication of polymeric mechanical sensors: i) PDMS/SiO2 composites, ii) PAAm/Au NP composites. The coherent reflectivity of SiO2 colloidal particle arrays was used to develop strain sensors while controllable localized surface plasmon resonance of Au NPs was employed for pressure sensors. These optical systems were separately associated with viscoelastic and elastic polymeric systems, and sensor properties were discussed.Master Thesis Fabrication of transparent polymer nanocomposites containing pmma-grafted CeO2 particles(Izmir Institute of Technology, 2011) Parlak, Onur; Demir, Mustafa; Demir, Mustafa MuammerThe composite materials prepared by transparent polymer and nanosized particles possess promising future in optical design and applications since their controllable optical properties. In this study, transparent/translucent composite films based on polystyrene (PS) and poly(methyl methacrylate) (PMMA)-grafted CeO2 nanoparticles were prepared. CeO2 nanoparticles were precipitated from Ce(NO3)3·6H2O and urea in dimethyl formamide at 120°C. The surface of the nanoparticles was modified with a polymerizable surfactant, 3-methacyloxypropyltrimethoxy silane (MPS) in situ at 0°C. The size of the particles was fixed to 18 nm in diameter. The particles were dispersed into a mixture of MMA:toluene solution. The free radical solution polymerization was carried out in situ at 60°C using benzoyl peroxide (BPO) as initiator. A PMMA layer is formed around CeO2 nanoparticles. The thickness of the shell ranged from 9 to 84 nm was controlled by the amount of BPO using 6 and 0.5 wt %, respectively with respect to monomer. The layer thickness was found to be inversely proportional with the amount of initiator. The resulting PMMA-grafted CeO2 particles were blended with PS in tetrahydrofuran and the solution was spin-coat on a glass slide. CeO2 content in the composite films was fixed to 5.5 wt %. The transmission of the films was examined by UV-vis spectroscopy. The transmission of the PS composite prepared by neat CeO2 particles was 71 %. It was increased to 85 % when the composite prepared with PMMA-grafted CeO2 particles whose PMMA thickness is 9 nm. We believe that the achievement in transparency is most probably due to the reduction in refractive index mismatch between CeO2 particles and PS matrix using PMMA layer at interface.Article Null Extinction of Ceria@silica Hybrid Particles: Transparent Polystyrene Composites(Amer Chemical Soc, 2015) Incel, Anil; Guner, Tugrul; Parlak, Onur; Demir, Mustafa M.; Demir, MustafaScattering of light in optical materials, particularly in composites based on transparent polymer and inorganic pigment nanopartides, is a chronic problem. It might originate mainly from light scattering because of a refractive index mismatch between the particles and transparent polymer matrix. Thus, the intensity of light is rapidly diminished and optical transparency is reduced. Refractive index matching between the pigment core and the surrounding transparent matrix using a secondary component at the interface (shell) has recently appeared as a promising approach to alter light scattering. Here, CeO2 (ceria) nanopartides with a diameter of 25 nm are coated with a SiO2 (silica) shell with various thicknesses in a range of 6.5-67.5 nm using the Stober method. When the hybrid core shell particles are dispersed into transparent polystyrene (PS), the transmission of the freestanding PS composite films increases over both the ultraviolet (UV) and visible region as the shell thickness increases particularly at 37.5 nm. The increase of transmission can be attributed to the reduction in the scattering coefficient of the hybrid particles. On the other hand, the particles in tetrahydrofuran (THF) absorb over UV and the intensity of absorption shows a systematic decrease as the shell thickness increases. Thus, the silica shell suppresses not only the scattering coefficient but also the molar absorptivity of the core ceria particles. The experimental results regarding the target shell thickness to develop low extinction (scattering + absorption) composites show a qualitative agreement with the predictions of Effective Medium Theory.Article Chitosan fiber-supported zero-valent iron nanoparticles as a novel sorbent for sequestration of inorganic arsenic(Royal Soc Chemistry, 2013) Horzum, Nesrin; Demir, Mustafa M.; Nairat, Muath; Shahwan, Talal; Demir, MustafaThis study proposes a new sorbent for the removal of inorganic arsenic from aqueous solutions. Monodispersed nano zero-valent iron (nZVI) particles were nucleated at the surface of electrospun chitosan fibers (average fiber diameter of 195 +/- 50 nm) by liquid phase reduction of FeCl3 using NaBH4. The material was characterized using SEM, TGA, XPS, XRD, and FTIR. The diameter of iron nanoparticles was found to vary between 75-100 nm. A set of batch experiments were carried out to elucidate the efficiency of the composite sorbent toward fixation of arsenite and arsenate ions. The ion concentrations in the supernatant solutions were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The results revealed that the chitosan fiber supported nZVI particles is an excellent sorbent material for inorganic arsenic uptake at concentrations ranging from 0.01 to 5.00 mg L-1 over a wide range of pH values. Based on XPS analysis, As(III) was found to undergo oxidation to As(V) upon sorption, while As(V) retained its oxidation state. By virtue of the successful combination of the electrospun fibers' mechanical integrity and the large reactivity of dispersed nZVI particles, the applicability of the resulting sorbent material in arsenic sorption holds broad promise.Master Thesis Selective loading of organofilic Ag nanoparticles in PS-PMMA blends(Izmir Institute of Technology, 2014) Tüzüner, Şeyda; Demir, Mustafa; Demir, Mustafa Muammer; Ebil, ÖzgençThe association of nanoparticles with polymer blends offers significant features beyond the advantages of polymer composites prepared by single homopolymer. Since the blends undergo phase separation due to incompatibility of the constituent polymers into various internal structures, the particles can be segregated into one of the phases. Different location of the particles allows to develop novel microstructures; and thus, control over physical properties. In this study, Ag nanoparticles were prepared by reduction of AgNO3 via NaBH4. The particles were capped by cetyl ammonium bromide (CTAB) and were mixed with equimass blend of polystyrene (PS) and poly(methyl methacrylate) (PMMA) in tetrahydrofurane (THF). The solid content of blend solution was fixed at 2.5% w/v. The concentration of the particles with respect to polymer blend was at 0.7 wt %. The composite film was cast on glass slide. Surface feature of the composite films was examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The surface of blend film without particles shows spherical pits with a size of 4.5 μm and rich in terms of PMMA. When particle size was small (diameter is around 20 nm), they preferentially located at the interface of the domains. The large particles with a diameter of 90 nm were found to locate in PMMA phase. Upon annealing of the composite film at 165 ˚C for 3 days, the particles move to the PS domains independent of the particle size and merely PS loaded composite is achieved.Article Experimental modeling of antimony sulfides-rich geothermal deposits and their solubility in the presence of polymeric antiscalants(Pergamon-elsevier Science Ltd, 2022) Karaburun, Emre; Sozen, Yigit; Ciftci, Celal; Sahin, Hasan; Baba, Alper; Akbey, Umit; Demir, Mustafa M.; Demir, MustafaAntimony (Sb)-rich geothermal deposits have been observed in many geothermal power plants worldwide. They occur as red-colored, sulfidic precipitates disturbing energy-harvesting by clogging the geothermal installations. In order to prevent the formation of this scale, information on its physicochemical features is needed. For this purpose, Sb-rich sulfide-based deposits were synthesized at controlled conditions in a pressurized glass reactor at geothermal conditions (135 degrees C and 3.5 bar). Various polymeric antiscalants with different functional groups, such as acrylic acid, sulphonic acid, and phosphonic acid groups were tested for their effect on Sb sulfide solubility. An additional computational study was performed to determine the binding energy of Sb and S atoms to these groups. The results suggest that sulfonic acid groups are the most affective. Therefore, it was concluded that these macromolecule containing sulfonic acid groups and poly (vinyl sulfonic acid) derivatives could potentially act as antiscalants for the formation of antimony sulfide.Article Fabrication and properties of novel porous ceramic membrane supports from the (Sig) diatomite and alumina mixtures(Elsevier, 2022) Aouadja, Faycal; Bouzerara, Ferhat; Guvenc, Cetin Meric; Demir, Mustafa M.; Demir, MustafaIn this paper, the manufacturing of macro-porous tubular ceramic supports for membranes is described. The novel supports are fabricated from natural diatomite and alumina raw materials using the extrusion method. The structure was analyzed by X-ray diffraction (XRD) and mercury porosimetry techniques; the presence of possible defects was investigated by scanning electron microscopy (SEM). The permeability has been measured from water flux in standard experiments. Experimental results show that the open porosity, the average pore size (APS), the pore size distribution, the strength, and the permeability of sintered supports, have been found to depend, mainly on the concentration of alumina (Al2O3) additive. Supports prepared with the addition of 10 wt.% of alumina and sintered at 1200 degrees C, can be considered as the most optimized; they have a porosity ratio of about 46%, an APS is around 7.7 mu m, a flexural strength value of about 28 MPa, and water permeability of around 15 m(3)h(-1) m(-2) bar(-1). Such materials could be of great interest in the supports fabrication for membrane application, for instance, water filtration. (C) 2021 SECV. Published by Elsevier Espana, S.L.U.Master Thesis Fabrication and characterization of ceramic fibers from preceramic polymers(Izmir Institute of Technology, 2019-12) Özmen, Ecem; Demir, Mustafa; Ahmetoğlu, Çekdar Vakıf; Demir, Mustafa MuammerCeramic fibers which are classified as oxide and non-oxide fibers are preferred to use in applications which are carried out at high temperature since they have high strength, low thermal expansion, corrosion, and oxidation resistance. Non-oxide fibers are generally produced using preceramic polymers by the spinning method. The production of ceramic materials using preceramic polymers by spinning method is more advantageous than other methods since the production of complex materials could be achieved at lower temperatures. The preceramic polymer family is basically classified as polysiloxane, polysilazane and polycarbosilane. In this thesis, it was aimed to obtain ceramic fiber in the most economical way. In this context, a spinning device was designed and made. Additionally, polysiloxane which is the most economical preceramic polymer was used to produce ceramic fiber. Polysiloxanes were spun by melt spinning. Obtained fibers were cured by different methods. As a result of pyrolysis, 65-130 μm thickness SiOC fibers were achieved.Article Effect of Alkali Metal Hydroxides on the Morphological Development and Optical Properties of Ceria Nanocubes Under Hydrothermal Conditions(Amer Scientific Publishers, 2011) Kepenekci, Ozlem; Emirdag-Eanes, Mehtap; Demir, Mustafa M.; Demir, MustafaNanocrystalline cerium(IV) oxide (CeO2, ceria) particles were produced via the hydrothermal treatment of cerium nitrate hexahydrate with various alkali metal hydroxides (MOH: M = Li, Na, K) Experimental conditions such as [MOH], reaction temperature, and reaction time were studied Particle morphology as well as size of crystallites was precisely controlled by choice of experimental conditions. While rod-shaped particles were obtained at 120 degrees C, well-defined nanocubes were formed at higher temperatures regardless of the choice of MOH. Examination of particle growth kinetics, in the final stages of crystallization, showed that particle growth rate is controlled by two different mechanisms. Grain boundary diffusion controls the particle growth in the presence of NaOH with an activation energy of 113.8 kj/mol and surface diffusion for LiOH ad KOH with the activation energy of 43.0-150.9 kj/mol, respectively. In addition, the particles exhibit strong violet and blue emissions at 400 nm and 370 nm. The former emission originates from excitation of a wide band gap of CeO2. The latter one is attributed to the trivalency of the cerium ion and appears to be sensitive to all the experimental conditions studied. Both extending reaction time and increasing temperature reduce the intensity of the 370 nm emission and increase the intensity of the 400 nm emission.
