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    Chitosan-Derived Porous Carbon for Efficient Adsorptive Removal of Amoxicillin and Doxycycline Antibiotics from Aqueous Systems
    (Springer Int Publ Ag, 2025) Turk, Feride N.; Arslanoglu, Hasan
    Traditional antibiotic removal techniques-such as coagulation, membrane filtration, ozonation, and biodegradation-are often inadequate for large-scale applications due to limiting factors including high operational costs, complex system design, and the formation of toxic by-products. In addition, the low selectivity levels of these techniques and the need for additional post-treatment make it difficult to achieve effective and sustainable water treatment goals. The phosphoric acid-activated chitosan-derived carbon adsorbent proposed in this study demonstrated superior adsorption capacities for both amoxicillin and doxycycline, owing to its high surface area and abundant functional groups, aligning with sustainability principles. Thus, it stands out as an economical and environmentally friendly alternative that directly solves the shortcomings of previous methods. High-performance activated carbon was synthesized via phosphoric acid activation of chitosan for the removal of amoxicillin (AMX) and doxycycline (DOC) antibiotics from aqueous solutions. The adsorption efficiency was systematically evaluated in batch experiments at temperatures ranging from 30 to 50 degrees C, initial antibiotic concentrations of 50-400 mg/L, and pH levels spanning from 3 to 13. The phosphoric acid activation process significantly influenced the physicochemical properties of the resultant activated carbon, enhancing its structural and textural characteristics. The activated carbon exhibited a substantial surface area of 998.02 m2/g, a pore volume of 0.485 cm3/g, and an average pore diameter of 2.55 nm, structure favorable for adsorption. Furthermore, kinetic analysis revealed that the adsorption process followed the pseudo-first-order model, indicating that physisorption was the dominant mechanism. Equilibrium data were best described by the Langmuir isotherm model, highlighting monolayer adsorption on a homogeneous surface. The maximum adsorption capacities for AMX and DOC were determined to be 227.18 mg/g and 299.07 mg/g, respectively, at 50 degrees C, demonstrating the high affinity of the adsorbent for these pharmaceutical contaminants. These findings indicate that chitosan-derived activated carbon is a cost-effective, sustainable material with strong potential for removing antibiotic contaminants from wastewater.
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    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.
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    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%.
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    Coordination-Driven Synthesis of Hierarchical Metal-Organic Network (MON) Particles for Efficient Cu(II) Removal: Structural Design-Characterization and Adsorption Performance
    (Springer Int Publ Ag, 2025) Turk, Feride N.; Arslanoglu, Hasan
    Copper (Cu(II)) contamination in aquatic systems is a pressing environmental issue due to its high toxicity, bioaccumulation potential, and adverse effects on ecosystems and human health. Developing adsorbent materials with high capacity, structural stability, and tunable surface chemistry is essential for efficient water purification. In this study, hierarchical metal-organic network (MON) particles were synthesized via a coordination-driven polycondensation of polyphenols and formaldehyde, resulting in robust, fiber-like structures with well-defined micro- (similar to 1.6 nm) and mesopores (similar to 13.9 nm) and a high surface area of 212.58 m(2)/g. The hierarchical pore architecture enhances mass transfer and adsorption kinetics, enabling a maximum Cu(II) adsorption capacity of 417.21 mg/g at 301.15 K, following the pseudo-second-order kinetic model and Langmuir isotherm. Thermodynamic analysis revealed that adsorption is spontaneous and endothermic, indicating strong chemisorption interactions through oxygen-containing functional groups. These results demonstrate that coordination-driven self-assembly represents an effective strategy for designing high-performance adsorbents with controlled pore structures and superior metal-binding capabilities. Beyond Cu(II) removal, this approach holds significant potential for developing next-generation materials for advanced water treatment, environmental remediation, and sustainable resource recovery.
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    DTPA-Assisted Selective Leaching of Mo, Co, Ni, and Al from Spent Hydrodesulfurization Catalysts
    (Springer, 2025) Turk, Feride N.; Arslanoglu, Hasan
    The extraction of cobalt (Co), nickel (Ni), molybdenum (Mo), and aluminum (Al) from an alumina-supported hydrodesulfurization (HDS) spent catalyst was examined using diethylene triamine pentaacetic acid (DTPA) as a chelating agent. To assess the impact of different metals on leaching efficiency, a roasting pretreatment was performed on powdered catalyst samples at various temperatures (300-700 degrees C) and durations (15-360 min). The morphological and textural modifications before and after roasting were characterized using scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The optimal roasting parameters were determined to be 600 degrees C for 180 min, under which the maximum metal extraction efficiencies were obtained: 71.05% for Mo, 80.06% for Co, 73.86% for Ni, and 15.33 % for Al. Leaching experiments were conducted with a particle size range of + 75 to - 30 mu m, a liquid-to-solid ratio of 15 mL/g, a DTPA concentration of 0.2 M, a leaching temperature of 60 degrees C, a duration of 180 min, and a stirring rate of 200 rpm. The findings highlight that both roasting temperature and time play a crucial role in enhancing metal dissolution from the spent catalyst.
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    Removal of Cr(VI) from Aqueous Solutions Using Thermal Power Plant Gas Purification Waste (Reduction and Adsorption of Hexavalent Chromium), Interpretation of Mechanism: Disposal of Waste and Residues
    (Springer Int Publ Ag, 2025) Saglam, Semanur; Eren, Sena; Turk, Feride N.; Arslanoglu, Hasan
    Flue Gas Desulfurization System (FGD) is a treatment system that has been made mandatory in thermal power plants for sulfur retention in recent years. FGD systems have been made mandatory in coal-based energy generating systems, especially in order to reduce the increasing greenhouse gas effect and to prevent the release of coal-derived sulfur oxides into nature. The hot waste steam from the boiler is sent to the FGD columns and milk of lime is fed to absorb the sulfur oxides. After treatment, thermal power plant gas treatment waste (PW) with a high content of gypsum is produced. In this study, the removal of chromium from aqueous solutions by PW was investigated. Cr(VI) adsorption studies were optimized using Taguchi analysis. In this context, L25 Taguchi orthogonal array was applied using 5 factors and 5 levels to optimize experimental parameters such as pH, dosage, contact time, concentration, temperature which affect adsorption. Elemental analysis, BET, TGA, XRD, XRD, FT-IR analyses were applied to determine the physicochemical properties of the waste. Adsorption isotherms and kinetics were also studied to investigate the Cr(VI) removal and mechanism of the material. The optimum experimental conditions were determined as initial pH 2.13, concentration 20 mg/L, dosage 22.5 g/L, time 12 h and temperature 32.5 degrees C by Taguchi method. Under these conditions, 100% Cr(VI) removal was successfully achieved. The results obtained show that PW is successful in Cr(VI) removal. The utilization of FGD waste is very important in terms of sustainability and environment. An alternative method has been presented as a solution to the increasing depletion of global water resources and the increasing need for land for PW storage.