Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
43 results
Search Results
Article Citation - Scopus: 4One-step hydrothermal synthesis of spinel manganese oxide ion-sieve from commercial Γ-Mno2 and its uptake performance for lithium(Elsevier Ltd, 2024) Toprak, Seyra; Demir, Mustafa MuammerThe selective extraction of lithium from aqueous systems necessitates efficient sorbent materials. Spinel-type lithium manganese oxide ion sieves (LMOs) have been bee recognized for their high performance in this application. However, the elevated market cost of the spinel form (λ-MnO2) raises economic concerns, posing challenges to the feasibility of the extraction process. In this study, the one-step hydrothermal synthesis of Li1.33Mn1.67O4 was carried out at 200 °C for 7 days using commercial γ-MnO2 powder and aqueous LiOH solution as reactants. The synthesized powder exhibited characteristic XRD reflections consistent with spinel Li1.33Mn1.67O4. Lithium ion-sieve (H1.33Mn1.67O4) was obtained by leaching the LMO product with dilute hydrochloric acid solution. The sorption capacity of γ-MnO2 is increased from 8.4 to 23.1 mg/g (C0=200 mg/L), this capacity is very close to the one of the commercial λ-MnO2. The synthesized spinel HMO sorbent achieved a maximum Langmuir adsorption capacity of 52.1 mg/g. The extraction efficiency reached 94% at the sorbent dose of 20 g/L. The distribution coefficients of metal ions were in the order Li+ > Ca2+ > K+ > Na+, emphasizing selective Li+ extraction from brines with high Na+ content. These findings highlight the successful development of a spinel-type lithium manganese oxide ion sieve from γ-MnO2 polymorph, which is nearly an order of magnitude cheaper than the selective λ-MnO2. The study addresses critical issue of economic feasibility in lithium extraction processes, providing a potential solution for the selective recovery of bulk lithium. © 2024 Elsevier LtdArticle Citation - Scopus: 6Lithium Extraction From Geothermal Brine Using Γ-Mno2: a Case Study for Tuzla Geothermal Power Plant(Elsevier Ltd, 2024) Toprak, S.; Yılmaz, Selahattin; Öncel, Ç.; Baba, Alper; Yılmaz, S.; Demir, Mustafa Muammer; Baba, A.; Koç, G.A.; Demir, M.M.Geothermal brines contain high concentrations of ions and form a source of various valuable elements. The isolation of the elements from their water systems is a great challenge when the gradual depletion of ores in mining is considered. Attempts have been made for a long time to isolate valuable elements from aqueous mixtures prepared in the laboratory. However, those studies might not reflect the complexity of natural systems and might yield results that deviate significantly from the performance in real field systems. In this study, sorption is used to extract lithium ions from a representative field, Tuzla Geothermal Power Plant (TGPP) Turkey, using a mini-pilot reactor introduced to the reinjection well of the plant. Electrolytic manganese dioxide (γ-MnO2), a relatively inexpensive material widely used as the cathode material in lithium-ion batteries, was employed as a sorbent material for lithium. The sorption/desorption performance of the novel γ-MnO2 was investigated under various conditions. Sorption is performed at 360K and 2 bars. The maximum sorption performance was obtained at 1 h in Tuzla GPP. The desorption experiments were performed in acidic solutions. The concentration of Li+ in the desorption solution was found to be 25 mg/L on average when 10 g of γ-MnO2 was dispersed into 30 mL of the acidic aqueous solution. The first desorption solution was used consecutively for collecting more Li+ ions through the desorption of fresh brine-treated powder samples (cumulative desorption). By repeating this process four times consecutively, 230 mg/L of Li+ was obtained in the desorption solution. Moreover, the reusability of the γ-MnO2 sorbent was examined. The sorbent powder showed almost 40% performance efficiency compared to virgin powder under the conditions employed in this study. The use of electrolytic γ-MnO2 sorbent for lithium adsorption was found to be a promising process for practical use in the separation of lithium from geothermal brines. © 2024Article Citation - WoS: 2Citation - Scopus: 5Experimental Modeling of Antimony Sulfides-Rich Geothermal Deposits and Their Solubility in the Presence of Polymeric Antiscalants(Elsevier, 2022) Karaburun, Emre; Sözen, Yiğit; Çiftçi, Celal; Şahin, Hasan; Baba, Alper; Akbey, Ümit; Yeşilnacar, Mehmet İrfan; Erdim, Eray; Regenspurg, Simona; Demir, Mustafa MuammerAntimony (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 °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 Citation - WoS: 10Citation - Scopus: 10Hydrogeology and Hydrogeochemistry of the Geothermal Systems and Its Direct Use Application: Balçova-Narlıdere Geothermal System, İzmir, Turkey(Elsevier, 2022) Baba, Alper; Sözbilir, Hasan; Sayık, Tolga; Arslan, Sinan; Uzelli, Taygun; Tonkul, Serhat; Demir, Mustafa MuammerThe Balçova-Narlıdere geothermal system, located in western Turkey, is an extensional domain type geothermal play. Geological, hydrogeological, and geothermal studies have been done in the Balçova-Narlıdere geothermal field since 1960. As a result of these studies, production and research wells were drilled in the area by both the public and private sectors. Of the 37 wells drilled in the Balçova-Narlıdere geothermal field, 26 were drilled by İzmir Geothermal Energy Company Inc. (16 productions, 4 re-injection, 4 gradientst, 2 unused) and 11 by the İzmir Governorship Investment Monitoring and Coordination Department and companies in the private sectors. There are two reservoirs, one shallow and one deep, in the geothermal field. Well depths are less than 200 m in the shallow reservoir. The deep production wells have depths ranging from 400 to 1,100 m and reservoir temperatures reaching 140 °C. The electrical conductivity (EC) values in the shallow production wells range from 1,200 to 1,500 µS/cm. EC values in the deep production wells vary from 1,871 to 2,025 µS/cm, and all geothermal fluids in the field are mineral-rich waters. In the İzmir geothermal district heating system, the newest technologies are used, and operational costs are very low. İzmir Geothermal Energy Company Inc. has been operating since 1996 and has reached 38,460 residences. The current capacity of the system is approximately 160 MWt. Cooling systems continue to spread in Turkey, focusing on electric air conditioning systems and geothermal heating systems, but both economic and applicability problems have slowed the expansion of cooling systems. However, İzmir Geothermal Energy Company Inc. began operating its first geothermal cooling application in Balçova in 2018, cooling 1,900 m2 of the indoor area by lithium bromide absorption and 90/85 °C geothermal temperature regime by supplying 6/9 °C clean cold water to the coolers in the buildings. These results show that the extensional domain type geothermal system in the Balçova-Narlıdere region is suitable for both heating and cooling applicationsArticle Citation - WoS: 9Citation - Scopus: 7Understanding the Impact of Sri2 Additive on the Properties of Sn-Based Halide Perovskites(Elsevier, 2022) Yüce, Hürriyet; Perini, Carlo A. R.; Hidalgo, Juanita; Castro-Mendez, Andres-Felipe; Evans, Caria; Demir, Mustafa MuammerOrganic-inorganic halide perovskites have been identified as favorable candidates for the next generation of photovoltaics. Adding alkali metal halides to perovskite films has been shown to be a viable option to improve the perovskite film quality and to modulate their fundamental properties. In this work, we perform optical and electron-beam based characterizations of mixed Sn/Pb based perovskite films to investigate the effect of the addition of the alkaline metal halide SrI2. By analyzing structural (X-ray diffraction), morphological (Scanning Electron Microscopy), optical (photoluminescence), and chemical properties (X-ray photoelectron spectroscopy), we show a complex interplay of effects upon addition of Sr2+ into the perovskite solution. Low concentrations of Sr2+ increases lattice strain, which hints at incorporation of the additive into the perovskite lattice and improves the film optoelectronic properties. As the additive concentration increases beyond 0.5 mol %, microstrain decreases. At concentrations >0.5 mol %, Sr2+ induces significant reduction of the average domain size, which impacts both structural and optical properties of the perovskite film.Article Citation - WoS: 3Citation - Scopus: 5Plasmon-Induced Spectral Tunability of Perovskite Nanowires(Elsevier, 2021) Gökbulut, Belkıs; Topçu, Gökhan; Demir, Mustafa Muammer; İnci, Mehmet NaciIn this paper, plasmon-assisted spectral tunability in random media, composed of Perovskite (CsPbBr3) nanowires surrounded by Au nanoparticle clusters in polystyrene matrix, is achieved. The interaction between the surface plasmons and the quantum sources is observed to generate photoluminescence from the higher excited state energy levels of the excited semiconductor nanowires, which results in a blueshifted fluorescence emission of 50 nm. The localized surface plasmon properties are also determined to be tuned by plasmonic pumping of the quantum sources at different resonant frequencies. Thus, the first observation of the tunable blueshifted fluorescence emission of the semiconductor nanocrystals surrounded by plasmonic nanoparticle aggregates is achieved. The dramatic changes in the spectral profiles of the fluorescent nanowires are attributed to be due to the fast dynamics surface enhanced fluorescence mechanism.Article Citation - WoS: 14Citation - Scopus: 16Bodipy-Based Organic Color Conversion Layers for Wleds(Elsevier, 2020) Yüce, Hürriyet; Güner, Tuğrul; Dartar, Suay; Kaya, Beraat Umur; Emrullahoğlu, Mustafa; Demir, Mustafa MuammerThe usage of organic dyes in phosphor conversion layer of WLED is an attractive approach since they have high molar extinction coefficient and photostability. Various types of organic pigments have been employed for this purpose such as BODIPY, perylene diimide, Rhodamine B, pyrene, Nile red, etc. Among those, BODIPY-based organic dyes appear to be promising candidate for white light generation. In this work, for the first time, red and green emitting BODIPY-based organic molecules have been used as colour conversion layer. These molecules were associated with PMMA in DMF solution and the resulting solution was subjected to electrospinning. Colorful electrospun mats were embedded into PDMS matrix and their free-standing PDMS composite films were used as color conversion layers over blue LED to produce white light such that CRI of 95 and CCT of 4200 K was achieved. These values show that BODIPY-based organic molecules containing fiber composites are promising candidates to be used as color conversion layers for white light applications.Article Citation - WoS: 7Citation - Scopus: 9Experimental Apparatus for Simultaneous Measurement of Triboelectricity and Triboluminescence(Elsevier Ltd., 2020) Arıca, Tuğçe A.; Topçu, Gökhan; Pala, Atamert; Demir, Mustafa MuammerTriboelectricity is a phenomenon caused by the accumulation of opposite electric charges on the surfaces of two different materials as a result of contact with each other. The phenomenon of emitting cold light when the material is subjected to physical deformation is called triboluminescence. This paper presents an experimental apparatus that allows simultaneous measurement of both triboelectricity and triboluminescence of a model composite system based on poly (vinylidene fluoride) (PVDF) and europium tetrakis (dibenzoylmethide) triethylammonium (EuD(4)TEA). While the former component was studied in contact-separation mode giving triboelectricity, the latter emits triboluminescence upon application of mechanical impact. The device was operated at varying range of frequencies from 0.5 to 4.8 Hz and the force in the range of 5.4-9.5 N. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 61Citation - Scopus: 64Electrospun Gelma Fibers and P(hema) Matrix Composite for Corneal Tissue Engineering(Elsevier Ltd., 2021) Arıca, Tuğçe A.; Güzelgülgen, Meltem; Yıldız, Ahu Arslan; Demir, Mustafa MuammerThe development of biocompatible and transparent three-dimensional materials is desirable for corneal tissue engineering. Inspired from the cornea structure, gelatin methacryloyl-poly(2-hydroxymethyl methacrylate) (GelMA-p(HEMA)) composite hydrogel was fabricated. GelMA fibers were produced via electrospinning and covered with a thin layer of p(HEMA) in the presence of N,N?-methylenebisacrylamide (MBA) as cross-linker by drop-casting. The structure of resulting GelMA-p(HEMA) composite was characterized by spectrophotometry, microscopy, and swelling studies. Biocompatibility and biological properties of the both p(HEMA) and GelMA-p(HEMA) composite have been investigated by 3D cell culture, red blood cell hemolysis, and protein adsorption studies (i.e., human serum albumin, human immunoglobulin and egg white lysozyme). The optical transmittance of the GelMA-p(HEMA) composite was found to be approximately 70% at 550 nm. The GelMA-p(HEMA) composite was biocompatible with tear fluid proteins and convenient for cell adhesion and growth. Thus, as prepared hydrogel composite may find extensive applications in future for the development of corneal tissue engineering as well as preparation of stroma of the corneal material. © 2020 Elsevier B.V.Article Citation - WoS: 36Citation - Scopus: 39Recent Developments of Colorimetric Mechanical Sensors Based on Polymer Composites(Royal Society of Chemistry, 2020) İnci, Ezgi; Topçu, Gökhan; Güner, Tuğrul; Demirkurt, Merve; Demir, Mustafa MuammerColorimetric mechanical (force, pressure, strain, and impact) sensors allow naked-eye visualization of existing structural deformations of a system occurring upon application of a mechanical action. The combination of mechanochromic materials with polymers offers a practical approach to designing and fabricating these sensors. Polymers as matrices can tolerate a wide range of forces and permits reusability of the sensors. On the other hand, mechanochromic materials provide unique colour properties depending on the type of mechanical action. They have also been frequently employed for the quantification of mechanical forces. As an example, non-centrosymmetric crystals are combined with polymers for sensing impact forces. Structures with photoluminescence and scattering and plasmonic resonances can be used to fabricate strain and pressure responsive composite materials, respectively. This study reviews recent advances in colorimetric mechanical sensor systems prepared using polymers and inorganic and organic mechanochromic materials working under a wide range of forces.