Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Gokelma, MertolPublisher: search.filters.publisher.Mdpi

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  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    A Viability Study of Thermal Pre-Treatment for Recycling of Pharmaceutical Blisters
    (Mdpi, 2024) Gokelma, Mertol; Diaz, Fabian; Capkin, Irem Yaren; Friedrich, Bernd
    Pharmaceutical packaging is one of the most used packaging types which contains aluminum and plastics. Due to increasing amounts of waste and rising environmental concerns, recycling approaches are being investigated. Since blisters usually contain a balanced amount of plastics and metals, most of the approaches focus on recycling only one material. Therefore, more sustainable recycling approaches which recover both plastic and aluminum fractions are needed. This study investigates the thermal behavior and degradation mechanisms of plastic-rich and aluminum-rich pharmaceutical blisters using various analytical techniques. Structural characterization revealed that plastic-rich blisters have a thicker profile with plastic and aluminum layers, while aluminum-rich blisters consist of plastic layers between aluminum sheets. Thermal degradation analysis showed two main stages for both types: plastic-rich blisters (polyvinyl chloride) exhibited significant weight loss and long-chain hydrocarbon formation between 210 and 285 degrees C, and aluminum-rich blisters (polyamide/nylon) degraded from 240 to 270 degrees C. Differential Scanning Calorimetry and Fourier Transform Infrared Spectroscopy analyses confirmed the endothermic behavior of such a transformation. The gas emissions analysis indicated an increased formation of gasses from the thermal treatment of plastic-rich blisters, with the presence of oxygen leading to the formation of carbon dioxide, water, and carbon monoxide. Thermal treatment with 5% O2 in the carrier gas benefited plastic-rich blister treatment, reducing organic waste by up to 80% and minimizing burning risk, leveraging pyrolytic carbon for protection. This method is unsuitable for aluminum-rich blisters, requiring reduced oxygen or temperature to prevent pyrolytic carbon combustion and aluminum oxidation.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Effects 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, Gabriella
    Municipal 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: 1
    Citation - Scopus: 1
    The Separation Behavior of Tib<sub>2</Sub> During Cl<sub>2</Sub>-free Degassing Treatment of 5083 Aluminum Melt
    (Mdpi, 2024) Li, Cong; Gokelma, Mertol; Stets, Wolfram; Friedrich, Bernd
    Utilizing titanium diboride (TiB2) inoculation for grain-refining purposes is a widely established practice in aluminum casthouses and foundries. Since this inoculation is usually implemented jointly with or between routine melt treatment steps ahead of casting, it is important to know whether and how other melt treatment processes affect the fade of TiB2 particles. For the present study, we investigated the influence of degassing process on the separation behavior of TiB2 particles in aluminum melt. Multiple sampling methods were employed and the samples were analyzed via spectrometer analysis. The removal efficiency of TiB2 during the gas-purging process of 5083 aluminum melt was confirmed to be significant over 10 min of treatment time. The rate at which the TiB2 content decays was found to increase with the impeller rotary speed from 400 rounds per minute (rpm) to 700 rpm. The separation rate of TiB2 particles was obtained to be 0.05-0.08 min(-1) by fitting the experimental data. Particle mapping results suggest that the TiB2 particles were separated to a dross layer. The obtained experimental results were used to quantitatively evaluate the conventional deterministic flotation model. The deviation between the conventional model and the experimental data was explained through the entrainment-entrapment (EE) model. Suggestions were made for future analytical and experimental works which may validate the EE model.