Gökelma, Mertol
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Gokelma, Mertol
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mertolgokelma@iyte.edu.tr
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03.09. Department of Materials Science and Engineering
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2ZERO HUNGER
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3GOOD HEALTH AND WELL-BEING
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4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
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7AFFORDABLE AND CLEAN ENERGY
6
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8DECENT WORK AND ECONOMIC GROWTH
3
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
9
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10REDUCED INEQUALITIES
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11SUSTAINABLE CITIES AND COMMUNITIES
2
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10
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5
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Documents
37
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214
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7
Documents
31
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196
Scholarly Output
35
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18
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11673/5655
Supervised MSc Theses
7
Supervised PhD Theses
1
WoS Citation Count
125
Scopus Citation Count
131
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WoS Citations per Publication
3.57
Scopus Citations per Publication
3.74
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15
Supervised Theses
8
| Journal | Count |
|---|---|
| Minerals, Metals and Materials Series | 4 |
| Black Sea Journal of Engineering and Science | 2 |
| JOM | 2 |
| Journal of Material Cycles and Waste Management | 2 |
| Journal of Sustainable Metallurgy | 2 |
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35 results
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Now showing 1 - 10 of 35
Master Thesis Synthesis of Titanium-Based Powders From Machining Waste by Using the Hydrogenation-Dehydrogenation Method(Izmir Institute of Technology, 2022) Çuhadaroğlu, Zeynep; Genç, Aziz; Gökelma, Mertol; Genç, Aziz; Gökelma, MertolSustainability and recycling activities have gained importance in almost every field all over the world. Many studies are conducted to recycle titanium and titanium alloys owing to their outstanding properties like low density, biocompatibility, corrosion resistance, and high strength-to-weight ratio. Although they offer superior properties, their usage is limited due to their high production cost and potential to generate waste, and therefore, recycling activities in this area should be expanded using an appropriate method. Cold hearth melting, vacuum arc re-melting, and hydrogenation and dehydrogenation process are widely used for recycling titanium scraps in industry. Among them, the hydrogenation and dehydrogenation (HDH) process has a significant environmental and economic impact. In this thesis, titanium powders were synthesized from additive manufacturing turnings. Ti-6Al-2Sn-4Zr-6Mo turnings were used as starting materials on which HDH characteristics were not investigated in the literature. Both hydrogenation and dehydrogenation parameters were studied to reach optimum conditions. Our results revealed that hydrogenation was accomplished at 500 °C for 120 minutes with 5 °C/minute heating rate. The optimum dehydrogenation condition was found at 600 °C for 90 minutes. Ti-6Al-2Sn-4Zr-6Mo powder with average 56 μm particle size was synthesized; however, hydrogen and oxygen concentrations in the powder were not at the desired level and non-spherical shaped powders were produced end of the process.Article Citation - WoS: 5Citation - Scopus: 7Characterization and Separation Behavior of Multi-Layers in Aluminum-Rich Waste Pharmaceutical Blisters(Springer, 2023) Çapkın, İrem Yaren; Gökelma, MertolAl-rich waste pharmaceutical blisters (WPBs) have a multi-layer structure that contains aluminum and polymer-based fractions. Although the aluminum mass in WPBs is less than typical aluminum packaging products such as beverage cans, establishing a feasible recycling procedure is possible by separating the fractions to recover both metal and plastic. Hydrometallurgical methods are mostly preferred for the separation of aluminum and plastic in multi-layered structures. This work reports the characterization of Al-rich WPBs and the separation behavior of aluminum and plastic layers. The effects of hydrochloric acid, acetic acid, formic acid, sulfuric acid, ethanol, acetone, and organic solvent (benzene–ethanol–water) on the separation behavior of layers were studied at different temperatures. Furthermore, the recycling yield of the aluminum fraction was experimentally assessed. © 2023, The Minerals, Metals & Materials Society.Master Thesis Characterization and Recyclability of Pharmaceutical Blisters(01. Izmir Institute of Technology, 2023) Çapkın, İrem Yaren; Gökelma, Mertol; Akkurt, Sedat; Gökelma, Mertol; Akkurt, SedatPackaging is one of the largest industries in the world. Pharmaceutical blister packages are the most preferred packaging type in the pharmaceutical industry. Especially after the COVID-19 pandemic, the use of pharmaceutical packaging has become widespread with the increasing demand for drugs. Pharmaceutical blister packages typically contain thin sheets of plastic and aluminium and generate substantial solid waste. Since these packages have a multi-layered and complex structure, they are difficult to recycle. Before recycling, plastic and aluminium need a separation process. Chemical separation or thermal processes can be used for separation. The aim of this study is to characterize different pharmaceutical blister types with SEM-EDS (Scanning electron microscopy- Energy dispersive X-ray spectroscopy), TGA (Thermogravimetric Analysis), DSC (Differential scanning calorimetry), ICP-MS (Inductively coupled plasma mass spectrometry), and FTIR (Fourier Transform Infrared Spectroscopy) and to review the different reagents used in the pharmaceutical blister layer separation process. In addition to thermal degradation, the parameters and results of the separation processes were evaluated using hydrochloric acid, formic acid, acetic acid, sulfuric acid, ethanol, acetone, and organic solvents. It also evaluates the recyclability of the separated layers (plastic and aluminium). Its recyclability was evaluated by melting the aluminium fraction under salt consisting of a mixture of NaCl-KCl-CaF2. The plastic fraction was obtained in solid and liquid form by thermal degradation and analysed by GC-TCD (Gas Chromatography-Thermal conductivity detector).Master Thesis EPDM Kauçuk Bileşiklerinde Si-kerf'in Dolgu Maddesi Olarak Kullanımı: Mekanik ve Termal Özellikler(2025) Aksoy, Özge; Demir, Mustafa Muammer; Gökelma, MertolBu tez çalışmasında, güneş paneli üretiminde oluşan silikon kerf (Si-kerf) atığının, etilen-propilen-dien monomer (EPDM) esaslı kauçuk bileşiklerinde takviye edici dolgu malzemesi olarak kullanılabilirliği araştırılmıştır. Sürdürülebilirlik hedefleri doğrultusunda yapılan bu çalışmada, Si-kerf'in farklı oranlarda kullanıldığı bileşiklerin reolojik davranışları, mekanik özellikleri, termal dayanımları ve yaşlanma sonrası performansları incelenmiştir. ASTM ve SAE J20 standartlarına uygun olarak yürütülen deneysel çalışmalarda, numuneler çekme testi, sertlik, yaşlanma dayanımı, şişme analizi ve çapraz bağ yoğunluğu ölçümleriyle karakterize edilmiştir. Ayrıca, hacimsel şişme yöntemi kullanılarak çapraz bağ yoğunluğu hesaplanmış, Flory-Rehner denklemi ile sayısal değerler elde edilmiştir. SEM ve EDX analizleri, Si-kerf parçacıklarının EPDM matrisi içinde yüzey modifikasyonuna ihtiyaç duymadan iyi dağılabildiğini ve dolgu-polimer etkileşiminin yeterli olduğunu göstermiştir. Elde edilen bulgular, geri kazanılmış silikanın özellikle %10–20 oranlarında kullanıldığında, CB100 referans bileşiği ile yakın hatta üstün mekanik ve termal performans sergilediğini göstermektedir. %20 Si-kerf ve %80 karbon siyahı içeren CB80–Skf20 formülasyonu, çekme dayanımı, çapraz bağ yoğunluğu ve termal yaşlanma performansı açısından en dengeli sonucu vermiştir. Bu çalışma, Si-kerf'in kauçuk endüstrisinde çevreci ve ekonomik bir alternatif olarak değerlendirilebileceğini göstermektedir.Review Citation - WoS: 41Citation - Scopus: 42Review on the Parameters of Recycling Ndfeb Magnets Via a Hydrogenation Process(American Chemical Society, 2023) Habibzadeh, Alireza; Küçüker, Mehmet Ali; Gökelma, MertolRegarding the restrictions recently imposed by China on the export of rare-earth elements (REEs), the world may face a serious challenge in supplying some REEs such as neodymium and dysprosium soon. Recycling secondary sources is strongly recommended to mitigate the supply risk of REEs. Hydrogen processing of magnetic scrap (HPMS) as one of the best approaches for magnet-to-magnet recycling is thoroughly reviewed in this study in terms of parameters and properties. The processes of hydrogen decrepitation (HD) and hydrogenation-disproportio-nation-desorption-recombination (HDDR) are two common methods for HPMS. Employing a hydrogenation process can shorten the production route of new magnets from the discarded magnets compared to other recycling routes such as the hydrometallurgical route. However, determining the optimal pressure and temperature for the process is challenging due to the sensitivity to the initial chemical composition and the interaction of temperature and pressure. Pressure, temperature, initial chemical composition, gas flow rate, particle size distribution, grain size, and oxygen content are the effective parameters for the final magnetic properties. All these influencing parameters are discussed in detail in this review. The recovery rate of magnetic properties has been the concern of most research in this field and can be achieved up to 90% by employing a low hydrogenation temperature and pressure and using additives such as REE hydrides after hydrogenation and before sintering.Article Citation - WoS: 1Citation - Scopus: 2An Investigation on Inclusions Forming During Remelting of Aluminum and Magnesium Scraps Under a Salt Flux(Springer, 2023) Çapkın, İrem Yaren; Gökelma, MertolDue to increasing environmental and economic concerns, the recycling of metals has been increasing in the last decades. Aluminum saves up to 95% of energy when recycled, and magnesium is one of the most common alloying elements in aluminum alloys, contributing to oxidation behavior. Both aluminum and magnesium have a high oxidation tendency during remelting, which raises the necessity for salt flux usage. Salt fluxes remove oxides and other surface contaminants from the target metal. Salt fluxes allow molten metal pieces to coagulate and form the molten bath. Furthermore, it prevents further oxidation of the metal. The presence of fluorides increases the metal yield by promoting coalescence. Although metals and salts are frequently interacting in such processes, there is still a lack of knowledge of the final and intermediate products of the interaction reactions. This study aims to contribute to the literature by investigating the interaction of aluminum and magnesium scraps with salt flux. As a result of the experiments, AlF3, MgF2, Al2O3, MgO, and MgAl2O4 were observed as the main phases in the aluminum and magnesium scraps dross. The presence of CaF2 in the salt flux, which is insoluble in water, was also observed in the analysis results. In addition, fluorine-containing compounds were observed as a result of chemical interactions among the F-, K-, and oxide layers.Article Citation - WoS: 1Citation - Scopus: 1Effects of Size and Mechanical Pre-Treatment on Aluminium Recovery From Municipal Solid Waste Incineration Bottom Ash(Mdpi, 2024) Gokelma, Mertol; Hatipoglu, Utku; Vallejo-Olivares, Alicia; Tuzgel, Rabia onen; Kivrak, Olcay; Bazoglu, Elif; Tranell, GabriellaMunicipal solid waste (MSW) is incinerated to reduce the volume and recover energy and materials. The generation of MSW has been increasing over the past few decades due to the increase in population and changing consumption habits. Rising environmental and economic concerns have increased the importance of waste treatment and recovery. Currently, MSW may take three alternate or parallel routes: direct recycling, incineration, or landfill, depending on the country and location. MSW incineration has three products in addition to energy: bottom ash, fly ash, and off-gas. After incineration, bottom ash usually still contains many materials to be recovered, such as glass, ceramics, and metals with a degree of oxidation. This study focuses on aluminium recovery from MSW incineration bottom ash from two different countries. The 2-30 mm fraction of aluminium particles was characterized in terms of its size, shape, and oxide thickness, and its effects on aluminium recovery were investigated. In addition, the ability of mechanical pre-treatment to remove oxides prior to melting was studied. The results were compared with the analytical modeling developed in this study. An increasing particle size and surface area resulted in an increase in aluminium recovery. Mechanical pre-treatment increased the yield for smaller particles to a larger extent than larger particles due to the difference in the oxide/metal ratio.Article Citation - WoS: 4Citation - Scopus: 4Rewas 2022: Developing Tomorrow's Technical Cycles(Springer, 2021) Fleuriault, Camille; Gökelma, Mertol; Anderson, Alexandra; Olivetti, Elsa A.REWAS, a sustainability driven conference within The Minerals, Metals & Materials Society (TMS), has a long history of bringing together academia and industry to exchange and reflect on the latest technology developments in the process optimization and waste management fields. The first edition of REWAS (REcycling and WASte symposium) took place in 1999. The scope of the conference has since then broadened to include environmental sustainability, resource management and manufacturing efficiency, liaising these developments to the metallurgical industry in a broader societal and systemic context. The 2022 edition of REWAS which will be hosted at the TMS 2022 Annual Meeting & Exhibition in Anaheim, California, provides a resolute outlook towards Developing Tomorrow's Technical Cycles. Within the metals and materials industry, technical cycles refer to the ensemble of strategies and processes applied to the development of sustainable product loops with the intent to eliminate waste and instead rethink, reuse and upcycle products. The success of technical cycles requires strengthening our circular approach for product life cycle design by providing guidelines and implementation examples to the developers, designers, policy makers and business managers. REWAS promotes such strategies within a priority sector identified for Circular Economy enablement: raw materials supply and management. REWAS 2022 consists of six symposia, and abstract submissions are expected in summer 2021. Topics include recycling and sustainability within the aluminum industry, specifically on casting technologies, recovery of metals from complex products and systems, decarbonization of the metallurgical and manufacturing industry, sustainable production and development perspectives, as well as automatization and digitalization for advanced manufacturing. REWAS 2022 will also include an honorary symposium for Dr. Diran Apelian, whose contributions in metals processing, aluminum and battery recycling, sustainability, education in materials science and more have shaped the path for sustainable materials processing.Editorial Materials Science and Engineering for Circularity: Challenges, Strategies and Solution(Elsevier, 2026) Beck, Gesa; Balle, Frank; Gokelma, Mertol; Shamsuyeva, Madina; Perotto, Giovanni; Gulia, KiranErratum Correction To: Effect of Mechanical Pre-Treatment on the Recovery Potential of Rare-Earth Elements and Gold From Discarded Hard Disc Drives (journal of Material Cycles and Waste Management, (2025), 27, 1, (257-269), 10.1007/S10163-024-02108-0(Springer, 2025) Habibzadeh, A.; Kucuker, M.A.; Gökelma, M.In this article the affiliation details for Mertol Gökelma were incorrectly given as “Department of Environmental Engineering, İzmir Institute of Technology, Izmir 35433, Turkey” and should have been deleted. © The Author(s), under exclusive licence to Springer Nature Japan KK, part of Springer Nature 2024.