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AKTAŞ, SERDAR

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AKTAŞ

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SERDAR

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2021 - 20222
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Subject: ADSORPTION ×

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    Recycling of precious materials by modified electrospun membranes
    (DESALINATION PUBL, 2021) AKTAŞ, SERDAR; Zeytuncu-Gokoglu, Bihter; Tasdemir, Reyhan Sengur; Tanc, Beril; Aktas, Serdar; Koyuncu, Ismail
    In this study, adsorption of gold (Au) and platinum (Pt) ions by electrospun polyacrylonitrile (PAN) natural keratin- modified membranes with high sulfur content and affinity toward precious metals were investigated. Different adsorption parameters, sorbent amount, contact time, temperature and pH of solution on adsorption (%) were studied in detail in batch sorption. First, a PAN nanofiber membrane was fabricated by an electrospinning technique as a low-cost method for producing nanofiber membranes and was then modified with the natural keratin (human hair) by hydrolysis in a basic solution. A PAN-keratin nanofiber membrane was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy (FTIR and SEM, respectively). FTIR verified the modification of PAN with keratin in which the spectrum of the resulting membrane showed significant changes, by using this modified nanofiber membrane, Au adsorption of 99% was achieved while the Pt adsorption showed a maximum of 37%. The reason for this finding may be because the electronegativity of Au is higher than Pt. When the adsorption isotherms were investigated, it was noted that the Langmuir isotherm fit better than the Freundlich isotherm. 1.0 M thiourea solution was used as a desorption reagent for both Au and Pt ions. Reusability studies showed that the adsorption capacity can remain up to 90 % after four times of usage. This finding indicates that the adsorption process of precious ions onto the electrospun membrane is a monolayer adsorption process.
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    Palladium recovery from spent Pd plating solutions using Lewatit TP 214 resin
    (2022-03-01) ÇETİNER, BURCU NİLGÜN; AKTAŞ, SERDAR; ÇETİNER B. N., Yegul E. U., Zeytuncu Gökoğlu B., AKTAŞ S.
    This study aims to explore the recovery of palladium (Pd(II)) ions using Lewatit TP 214 resins. Waste Pd(II) ions with ammonia complex procured from a precious metal plating were selected as the source solution. In the experimental studies, two stock solutions of 60 ppm Pd(II) with a pH value of 4.0 and 7.5 were prepared as initial solutions. The experiments were performed by altering four parameters: solution pH, time 15-180 min, temperature 25 degrees C-60 degrees C, and amount of resin 100-400 mg. It was proved that the recovery percentage increased with higher temperature and resin at lower pH values. The Pd(II) recovery percentage increased with a temperature rise, reaching 100% after 40 min at pH 4.0 and 60 degrees C. On the other hand, a bit lower efficiency (95%) was attained after 180 min at pH 7.5 and 60 degrees C. Using Lewatit TP 214, the computed activation energies for Pd(II) recovery are 17.73 and 15.62 kJ/mol at pH 4.0 and 7.5, respectively. Considering these activation energy values, a mixed mechanism dominated the recovery of Pd(II).