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- MakaleAçık Erişim2026Scopus SJRQ3Optimized bioleaching of spent FCC catalysts for the recovery of critical metals
Erust, Ceren; Altındaş, Mediha Demet Okudan
Spent fluid catalytic cracking (FCC) catalysts, generated in large volumes by petroleum refining, represent a promising secondary source of critical metals such as lanthanum, cerium, titanium, and vanadium. In this study, a biohydrometallurgical approach was applied to recover these metals using Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans. The spent FCC catalyst, supplied by petroleum refinery, was characterized through WD-XRF, XRD, SEM-EDS, and ICP-OES analyses, confirming significant concentrations of La2O3 (1.44%), TiO2 (1.43%), and CeO2 (0.23%). Bioleaching experiments were conducted under varying initial ferrous ion concentrations (1–9 g/L) and pulp densities (5–20% w/v) at 35°C over 14 days. Results revealed that the optimal conditions for maximum recovery occurred at 5 g/L Fe2+ and 10% pulp density, achieving leaching efficiencies of 95.5% for La, 90.5% for Ce, 92.5% for Ti, and 60.8% for V within seven days. Beyond this period, efficiency decreased due to jarosite formation and microbial activity constraints. The findings confirm that bioleaching is a cost-effective and sustainable route that aligns with circular economy principles by reducing reliance on virgin rare earth mining while mitigating the environmental impact of catalyst disposal.
- MakaleYalnız künye2024Scopus SJRQ1Lanthanum-based magnetic biopolymers for brilliant green removal from aqueous solutions
Karaaslan Ayhan, Nagihan
In this study, lanthanum (La)-based magnetic biopolymers were synthesized, and the first adsorption study was conducted on the removal of brilliant green dye from aqueous water with these biopolymers. For the adsorption study, adsorption parameters were investigated and the ideal adsorption conditions determined for the removal of brilliant green dye from aqueous solutions are pH 11, t 60 min, m 10 mg, C0 25 mg/L, T 298 K. It was determined that the adsorption process was compatible with the single-layer Langmuir isotherm, and maximum adsorption capacity obtained according to the Langmuir isotherm was calculated as 256.41 mg/g. The adsorption process was found to be in accordance with the pseudo-second-order, and the adsorption process was explained by intra-particle diffusion. According to studies of adsorption thermodynamics, it has been established that the nature of the adsorption reaction is spontaneous, and this process is endothermic and has increasing randomness. Moreover, the reusability of magnetic lanthanum/alginate (La/Alg) biopolymers was investigated, and it was determined that the biopolymers could be used successfully. In summary, brilliant green dye has been successfully removed with simple, low-cost, environmentally friendly, and easily obtained magnetic La/Alg biopolymers. It can be stated that even low amounts of these biopolymers can be effective in the treatment of highly concentrated dye wastewaters.
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İncele - Yüksek Lisans TeziAçık Erişim2023Karbon elyaf takviyeli polietilenin mekanik, termal vefiziksel özelliklerine nadir toprak elementlerinin etkileri
Pamuk Ayikurt
Bu çalıĢmada termoplastiklerin önemli bir üyesi olan polietilenin mekanik, termal ve morfolojik özellikleri üzerine karbon elyaf tozu ve nadir toprak elementlerinin etkileri incelenmiĢtir. Polietilen olarak alçak yoğunluklu (AYPE) ve yüksek yoğunluklu (YYPE) polietilenler ayrı ayrı çalıĢılmıĢtır. Nadir toprak elementi olarak ise %90 ve üzeri saflıkta lantan ve seryum oksitler kullanılmıĢtır. Öncelikle bu elementler saf suda ayrı ayrı çözüldükten sonra karbon elyaf tozu bu çözeltilere karıĢtırıldı. Lantan ve seryumun karbon elyafa emilimi sağlandıktan sonra bu karıĢımlar hazırlanan alçak yoğunluklu polietilen çözeltisi içerisine dökülerek termoplastik karakterde takviye elemanı geliĢtirildi. Lantan ve seryum esaslı olarak ayrı ayrı elde edilen bu takviye elemanları kurutulup granül hale getirildikten sonra çalıĢmada kullanılacak olan matris malzemeler (AYPE ve YYPE) ile ayrı ayrı ağırlıkça %5, %10, %20 ve %30 oranlarında önce mekanik olarak daha sonrada uygun sıcaklıklarda ekstrüzyonda homojen olarak karıĢtırıldı. Ekstrüzyonda homojen hale getirilen bu karıĢımlar ekstrüzyon çıkıĢında soğutuldu ve akabinde kırıcıdan geçirilerek granül hale getirildi. Elde edilen bu granüller plastik enjeksiyon makinası ile kalıplara basılarak standart çekme çubukları üretildi. Üretilen bu çekme çubuklarının mekanik olarak çekme, eğilme, izod darbe ve sertlik analizleri gerçekleĢtirildi. Elde edilen karıĢımların camsı geçiĢ sıcaklıkları, erime sıcaklıkları ve kütle kayıplarının belirlenmesi için ise TGA/DTA analizi yapıldı. Aynı zamanda matris ve dolgu arasında ki bağlanma mekanizmasının belirlenmesi için ise numunelerin kesit görüntüleri elektron mikroskobu ile incelendi. Hem AYPE hem de YYPE içerisinde artan takviye elemanı miktarına bağlı olarak değiĢimler grafiklerle gösterilerek tartıĢıldı.
- MakaleYalnız künye2023Scopus SJRQ1Improving dielectric properties, electrical conductivity, and thermal properties of biodegradable polymer composites prepared with lanthanum
Torgut, Gulben; Ayhan, Nagihan Karaaslan; Acikses, Aslisah
The precipitation method was adapted to synthesize the poly(ε-caprolactone-copolymer- ethylene oxide) (ε-CL-co-EO) composite with the salt of lanthanum (La), a rare earth element. This salt was incorporated into the polymer of different weight percentages to study how it affects the thermal and dielectric properties of the polymer. The resulting products were characterized by Fourier Transform Infrared Spectroscopy, X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and thermogravimetric analysis. XRD and SEM data show that the polymer mixes homogeneously with the metal salt. Thermal degradation data show that the thermal stability of composites synthesized with La is lower than that of pure polymer. The dielectric properties and A.C conductivity measurements of the composites were investigated by using impedance analyzer in the frequency range (100 Hz to 20 kHz) at room temperature. The electrical property results of (ε-CL-co-EO)/La composites displayed that dielectric constant (έ), dielectric loss (ε"), tan delta (tan δ) and A.C electrical conductivity (σac) increase with increasing La content. The largest conductivity of (ε-CL-co-EO)/La composite filled with 20 wt% La was 8.80 × 10−8 S/cm, which was 162% times pure (ε-CL-co-EO). In addition, impedance (IZI) of composites was evaluated from the dielectric data. This procedure is eco-friendly and easy to handle, which provides a promising route to polymer composites in the application of the conductivity field.
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