Yazar "Ugur, Mucahit" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Co-pyrolysis of waste tires and Platanus orientalis leaves: thermogravimetric characterization, kinetic modeling, and resource valorization potential
    (Wiley, 2026) Turk, Feride N.; Ugur, Mucahit; Arslanoglu, Hasan
    This study investigates the co-pyrolytic behavior of waste tires (WT) and Platanus orientalis leaves (SL) as hybrid feedstocks for thermochemical valorization. Pyrolysis experiments were conducted under nitrogen atmosphere using thermogravimetric analysis across a temperature range of ambient to 745 degrees C, with heating rates of 5, 10, 15, 20, and 25 K min-1. Five blend ratios (100% WT, 75/25, 50/50, 25/75, 100% SL by mass) were assessed to evaluate thermal degradation profiles and kinetic characteristics. A Box-Behnken experimental design within the response surface methodology (RSM) framework was employed to optimize the effects of temperature, heating rate, and blend ratio on pyrolysis performance. The statistical model showed a high predictive capability with R 2 >0.995. Kinetic parameters were calculated using Coats-Redfern, Flynn-Wall-Ozawa, and Kissinger methods, with activation energies for the major decomposition stage (Stage 3C) ranging from 114.3 to 125.2 kJ mol-1. A significant negative correlation was found between activation energy and SL content (r = -0.82), while WT content showed a positive correlation (r = 0.87), indicating that biomass reduces the energy barrier for thermal degradation. Fourier transform infrared analysis confirmed the breakdown of functional groups such as -OH, C-O, and aromatic C-C after pyrolysis, indicating extensive structural transformation. Scanning electron microscopy imaging revealed morphological changes from fibrous structures in SL to carbonized, fractured surfaces in the char. Energy-dispersive X-ray spectroscopy analysis indicated a high carbon content (91.2%), supporting the suitability of the product for energy applications. Overall, the study demonstrates the synergistic potential of WT and SL in co-pyrolysis, improving thermal behavior, reducing activation energy, and yielding carbon-rich products. These findings support the development of integrated waste-to-energy strategies aligned with circular economy principles.
  • [ X ]
    Öğe
    Comparative Assessment of Lead (Pb) and Zinc (Zn) Leaching Behavior from Zinc Extraction Residues Using Monovalent and Divalent Chloride Salts
    (Springer, 2025) Turk, Feride N.; Ugur, Mucahit; Arslanoglu, Hasan
    It is crucial for waste management to economically utilize the solid leach residues released in zinc production facilities, classified as hazardous waste because of the metals they contain, without harming the environment and human health. Although the disposal of these residues often requires special technologies, hazardous wastes are left in the environment or landfills because of the expense of these technologies and the inadequacy of legal sanctions in some cases. Therefore, it is important from both an economic and environmental perspective to evaluate these residues and return them to the industry. This work aims to extract Pb and Zn metals from zinc extraction residuals in the presence of various chloride salts such as magnesium chloride, calcium chloride and potassium chloride. For this purpose, the chemical analysis of ZER (zinc extraction residual) was conducted by the LiBO2 fusion-HNO3 solubilization method, and its Pb and Zn contents were found to be 15.88% and 10.02%, respectively. The leaching experiments were carried out in two ways. The first group of leaching experiments was carried out by boiling under reflux and stirring, and KCl salt was found to be the most suitable leaching agent. The second group of experiments was performed in Erlenmeyer flasks using a shaker incubator at different temperatures (25-55 degrees C) and at varied KCl concentrations (0.6-5 N). Based on the experimental findings, the extraction efficiency of lead (Pb) is substantially higher than that of zinc (Zn) in the presence of all investigated chloride salts. While Pb dissolution demonstrates a strong dependence on the chloride salt concentration, particularly beyond certain threshold levels, the Zn extraction yield exhibits minimal variation across the same concentration range. This indicates that chloride ions preferentially promote the solubilization of Pb species, likely due to the formation of more stable and soluble Pb-Cl complexes, whereas Zn appears to have a lower affinity for chloride complexation under the studied leaching conditions. On the other hand, the Pb extraction value increased with increasing KCl concentration, and it reached 80.9% in KCl concentration of 4 N. In addition, the amount of Zn dissolved at different KCl concentrations plateaued at 25%.