Yazar "Yaras, Ali" seçeneğine göre listele

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    Cleaner production of polyurethane (PU) foams through use of hydrodesulfurization (HDS) spent catalyst
    (Springer Heidelberg, 2022) Yaras, Ali; Nodehi, Mehrab; Ustaoğlu, Abid; Arslanoğlu, Hasan; Sarı, Ahmet; Gencel, Osman; Özbakkaloğlu, Togay
    Due to the increased population in the urbanized areas, considerable attention is being paid on the development of energy-efficient buildings. In construction, the use of insulating foams has grabbed considerable attention in recent decades due to their porous structure that can reduce thermo-acoustic conductivity leading to higher energy efficiency. Nonetheless, the production of certain foams (e.g., polymer foams) is based on harmful chemical substances, such as isocyanate, as well as having difficulty being recycled. In this regard, this study adopted the use of hydrodesulfurization (HDS) spent catalyst, which is a byproduct of petroleum industry and is known to be a hazardous solid waste material, to produce a more environmentally friendly composite foam with lower thermal conductivity. In this sense, a series of material property tests, as well as thermal conductivity test, have been conducted. In addition, to further confirm the impact of HDS inclusion in the produced foams, energy cost savings and CO2 emission reduction based on their actual application in four different environments and four different fuel types for heating have been evaluated. The results are found to be highly promising and point to the great potential of utilizing HDS spent catalyst as a hazardous waste to enhance the efficiency of foams leading to CO2 emission and energy use reduction by up to 68.79 kg/m(2) and 8.6 kWh/m(2), respectively. Finally, this would reduce the heating cost, up to 0.69 $/m(2) in an idealized building. In the end, suggestions for future studies in this area are also provided.
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    Electrochemical Detection of Uric Acid Based on a Carbon Paste Electrode Modified with Ta2O5 Recovered from Ore by a Novel Method
    (American Chemical Society, 2023) Rajendrachari, Shashanka; Arslanoğlu, Hasan; Yaras, Ali; Golabhanvi, Shailesh M.
    Except for well-known commercial production procedures, this study demonstrates that Ta2O5 particles can be produced. Through a series of steps, highly pure Ta2O5 particles (99.45%) were produced from the raw ore. We have electrochemically detected one of the important nitrogenous compounds present in urine, uric acid, by a Ta2O5 particle-modified carbon paste electrode (Ta2O5-MCPE) using cyclic voltammetry. The prepared electrode has shown excellent current sensitivity at a pH of 6.0 phosphate-buffered solution. We have found that 4 mg Ta2O5-MCPE has recorded the highest current sensitivity of 75.75 mu A. The oxidation peak current was varied with the uric acid concentration in the range from 1 to 5 mM at 4 mg Ta2O5-MCPE. We have calculated the electrode-active surface area for a bare carbon paste electrode and 4 mg Ta2O5-MCPE using the Randles-Sevcik equation, and the values were found to be 0.0202 and 0.0450 cm(2), respectively. On the other hand, the calculated values of limit of detection and limit of quantification were reported as 0.5937 x 10(-8) M and 1.9791 x 10(-8) M, respectively, for the prepared 4 mg Ta2O5-MCPE. The interfere studies revealed that the variation in the electrochemical signal of uric acid in the presence of different metal ions was found to be less than +/- 5%.
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    Recovery of valuable metals from spent hydrodesulfurization (HDS) catalysts: A comprehensive research review and specific industrial cases
    (Academic Press Ltd- Elsevier Science Ltd, 2025) Yu, Haoran; Liu, Shuo; Yaras, Ali; Enkhchimeg, Battsengel; Hu, Linchao; Zhang, Wenyi; Peng, Mingguo; Arslanoğlu, Hasan
    Spent hydrodesulfurization (HDS) catalysts, produced in the petroleum refining process, are usually classified in hazardous solid waste. Recovery of valuable metals from spent HDS catalyst not only reduce substantially environmental risk but is an important way to alleviate global resource shortages for high-valuable metals. This study reviews numerous references regarding to recovery valuable metals from spent HDS catalyst in last decades, and divided current methods into three processes: pretreatment, oxidation-leaching, and separationpurification processes. Roasting and solvent washing usually emerge as primary methods in the pretreatment process, and effectively eliminate the surface oily substances and sulfur. Sodium salt roasting-leaching are considered as higher efficient among all leaching methods. The application of organic acid in the leaching can separate valuable metals selectively and simplify subsequent purification steps. In separation-purification processes, solvent extraction is still a standout method to isolate challenging metals such as Mo, W and V. However, the burgeoning field of ion imprinting technology exhibits the promising potential. Additionally, Random Forest and XGBoost model are used to analyze reported methods to recovery Mo and Ni and predict the key factor to regulate recovery efficiency. The results show that Mo recovery process is depended on the spent HDS characteristics and solid-liquid ratio in leaching process, while Ni recovery processes is depended on the roasting time and roasting temperature. Finally, serval specific industrial cases on recycling valuable metals from spent HDS were given, and found that sodium salt roasting-water leaching process was still frequent used in practical application due to its characteristics of high efficiency and low cost.