Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
Browse
9 results
Search Results
Article Pomza ve Nsdd-pomza ile Sabit Yataklı Kolon Reaktörde Metilen Mavisi Giderimi: Deneysel ve Modelleme Çalışması(2019) Balcı, Esin; Ökten, Hatice Eser; Genişoğlu, Mesut; Recepoğlu, Yaşar Kemal; Gören, Ayşegül YağmurNano sıfır değerlikli demir (nSDD) yüksek renk konsantrasyonlarına sahip tekstil atıksularının arıtımında ekonomik ve çevre dostu bir adsorban olarak ortaya çıkmaktadır. Ancak nSDD partikülleri sulu çözeltilerde elektrostatik etkileşimler sebebiyle kolayca topaklaşmakta ve bu da arıtma veriminin düşmesine neden olmaktadır. Dolayısıyla düşük maliyetli, doğal poröz yapıda ve ortalama 2m2/gr spesifik yüzey alanına sahip pomza, nSDD topaklaşmasını önleyici bir malzeme olarak kullanılabilir. Bu çalışmada sadece pomza ve pomzanSDD (ağırlıkça 9:1) karışımının kullanıldığı kolon reaktörde 25, 50, 75 ve 100 mg/L metilen mavisi konsantrasyonları için arıtma verimleri incelenmiştir. Pomzanın ve pomza-nSDD karışımının 100 mg/L metilen mavisi deneyindeki toplam kapasiteleri sırasıyla 2,8 ve 4,2 mg/g-adsorban olarak bulunmuştur. Özellikle düşük konsantrasyonlarda, pomza-nSDD karışımının arıtma performansını önemli ölçüde arttırdığı görülmüştür. Thomas modeli deneysel verilere uygulanmış ve modelin öngörü gücünün düşük konsantrasyonda yüksekken, yüksek konsantrasyonlarda ortalama olduğu kanısına varılmıştır.Article Citation - Scopus: 2A Comparative Assessment for Efficient Oleuropein Extraction From Olive Leaf (olea Europaea L. Folium)(Murat Yakar, 2023) Recepoğlu, Yaşar Kemal; Gümüşbulut, Gülin; Yüksel Özşen, AslıSince oleuropein has long been known in the health sector and is abundant directly in our country as the fourth largest olive producer, oleuropein, the predominant phenolic ingredient in olive leaves, was recovered in this study using Soxhlet extraction. The effects of different solvent types (acetonitrile, ethanol, methanol, and water), extraction period (4 cycles, 4 h, and 8 h), particle size (250-500 µm and 900-2000 µm), and pretreatment of olive leaves on the yield of oleuropein were examined to determine the maximum yield. A greater oleuropein yield was obtained when the particle size of olive leaves utilized for extraction was lowered. Furthermore, aqueous solvents revealed a higher yield of oleuropein than pure solvents and prolonging the extraction duration resulted in a significant increase in the amount of oleuropein extracted. On the other hand, pretreatment of olive leaves resulted in a reduction in oleuropein output. As a result, with 36% extraction efficiency in terms of olive leaf conversion, the highest oleuropein extraction yield was obtained as 13.35 mg g-1 dry leaf for 8 h of extraction time using olive leaves with a particle size of 250-500 µm and an 80% methanol solution as solvent. © Author(s) 2023.Article Citation - WoS: 7Citation - Scopus: 7Cross-Linked Phosphorylated Cellulose as a Potential Sorbent for Lithium Extraction From Water: Dynamic Column Studies and Modeling(American Chemical Society, 2022) Recepoğlu, Yaşar Kemal; Yüksel, AslıPhosphorylated functional cellulose was cross-linked with epichlorohydrin at different ratios because it is a very hydrophilic substance that instantly swells to form a hydrogel when it comes into contact with water. It was aimed to utilize a continuously packed bed column to recover lithium from water under varying operating conditions such as flow rate and bed height. The characterization results confirmed cross-linking based on morphology, structure, surface area, and thermal stability differences. Lithium recovery was more efficient with a low flow rate, but the dynamic sorption process was independent of bed height. The total capacities at the three flow rates with 1.5 cm bed height were 33.56, 30.15, and 25.54 mg g-1, and the total saturation times at the three different bed heights with 0.5 mL min-1 flow rate were 659, 1001, and 1007 min, respectively. Only 15.75 mL of 5% H2SO4 solution was required to desorb approximately 100% of Li from the saturated sorbent.Article Citation - WoS: 31Citation - Scopus: 35Electrochemical Degradation of Methylene Blue by a Flexible Graphite Electrode: Techno-Economic Evaluation(American Chemical Society, 2022) Gören, Ayşegül Yağmur; Recepoğlu, Yaşar Kemal; Edebali, Özge; Şahin, Çağrı; Genişoğlu, Mesut; Ökten, Hatice EserIn this study, electrochemical removal of methylene blue (MB) from water using commercially available and low-cost flexible graphite was investigated. The operating conditions such as initial dye concentration, initial solution pH, electrolyte dose, electrical potential, and operating time were investigated. The Box-Behnken experimental design (BBD) was used to optimize the system's performance with the minimum number of tests possible, as well as to examine the independent variables' impact on the removal efficiency, energy consumption, operating cost, and effluent MB concentration. The electrical potential and electrolyte dosage both improved the MB removal efficiency, since increased electrical potential facilitated production of oxidizing agents and increase in electrolyte dosage translated into an increase in electrical current transfer. As expected, MB removal efficiency increased with longer operational periods. The combined effects of operating time-electrical potential and electrical potential-electrolyte concentration improved the MB removal efficiency. The maximum removal efficiency (99.9%) and lowest operating cost (0.012 $/m3) were obtained for initial pH 4, initial MB concentration 26.5 mg/L, electrolyte concentration 0.6 g/L, electrical potential 3 V, and operating time 30 min. The reaction kinetics was maximum for pH 5, and as the pH increased the reaction rates decreased. Consequent techno-economic assessment showed that electrochemical removal of MB using low-cost and versatile flexible graphite had a competitive advantage.Article Citation - WoS: 40Citation - Scopus: 47Boron in Geothermal Energy: Sources, Environmental Impacts, and Management in Geothermal Fluid(Elsevier, 2022) Mott, A.; Baba, Alper; Hadi Mosleh, Mojgan; Ökten, Hatice Eser; Babaei, Masoud; Gören, Ayşegül Yağmur; Feng, C.; Recepoğlu, Yaşar Kemal; Uzelli, Taygun; Uytun, Hüseyin; Morata, Diego; Yüksel Özşen, AslıThe problem of hazardous chemicals in geothermal fluid is a critical environmental concern in geothermal energy developments. Boron is among the hazardous contaminants reported to be present at high concentrations in geothermal fluids in various countries. Poor management and inadequate treatment of geothermal fluids can release excessive boron to the environment that has toxic effects on plants, humans, and animals. Despite the importance of boron management in geothermal fluid, limited and fragmented resources exist that provide a comprehensive understanding of its sources, transport and fate, and the treatment strategies in geothermal energy context. This paper presents the first critical review from a systematic and comprehensive review on different aspects of boron in geothermal fluid including its generation, sources, toxicity, ranges and the management approaches and treatment technologies. Our research highlights the origin of boron in geothermal water to be mainly from historical water-rock interactions and magmatic intrusion. Excessive concentrations of boron in geothermal fluids have been reported (over 500 mg/L in some case studies). Our review indicated that possible boron contamination in geothermal sites are mostly due to flawed construction of production/re-injection wells and uncontrolled discharge of geothermal water to surface water. The dominancy of non-ionic H3BO3 species makes the selection of the suitable treatment method for geothermal waters limited. Combining boron selective resins and membrane technologies, hybrid systems have provided effluents suitable for irrigation. However, their high energy consumption and course structure of boron selective resins encourage further research to develop cost-effective and environmentally friendly alternatives.Article Citation - WoS: 42Citation - Scopus: 44Boron Carbon Nitride Nanosheets in Water and Wastewater Treatment: a Critical Review(Elsevier, 2022) Recepoğlu, Yaşar Kemal; Gören, Ayşegül Yağmur; Vatanpour, Vahid; Yoon, Yeojoon; Khataee, AlirezaThe availability and accessibility of clean and secure water supplies are pressing technological and scientific issues worldwide. As a result of global water constraints, wastewater treatment and reuse are being evaluated as feasible alternatives to fresh water for agricultural irrigation and domestic and industrial purposes. Boron carbon nitride (BCN) nanosheets have been studied intensively in the last decade in batteries, biosensors, and capacitors, and for use as catalysts, and they have recently been used in wastewater treatment. BCN materials, along with their synthesis processes, characteristics, and application areas in water and wastewater treatment, are discussed thoroughly in this paper. Additionally, synthesis processes for ternary BCN compounds, including chemical vapor deposition, ion beam-aided deposition, magnetron sputtering, and pulsed laser deposition, are described. BCN materials have also been explored because of their flexible electrical features, excellent mechanical strength, outstanding unreactivity, and significant stability, which make them appropriate for a range of severe environment applications. Thus, the use of BCN materials as photocatalysts and adsorbents and in electrochemical reduction and capacitive deionization are also discussed thoroughly. The highest ammonia production of 172,226.5 μg/h.mg.cat and faradic efficiency of 95.3% have been obtained using the BCN@Cu/CNT catalyst, whereas the ammonia production and FE values for metal-free BCN are 7.75 μg/h.mg.cat and 13.8%. Moreover, the maximum attained adsorption capacities of BCN nanosheets for Pb2+ and Hg2+ are 210 and 625 mg/g, respectively. Overall, this review indicates that essential work on BCN nanosheets is still needed. Future research should focus on the development of BCN nanostructures to encourage multidisciplinary research.Article Methylene Blue Removal of Fixed-Bed Column Reactor With Pumice and Nzvi-Pumice: Experimental and Modeling Study(Süleyman Demirel Üniversitesi, 2019) Genişoğlu, Mesut; Gören, Ayşegül Yağmur; Balcı, Esin; Recepoğlu, Yaşar Kemal; Ökten, Hatice EserNano zero-valent iron (nZVI) emerges as a low cost and eco-friendly adsorbent to treat textile wastewater, which is rich in dye content. However nZVI particles can easily agglomerate in aqueous environment due to electrostatic interaction, decreasing their treatment efficiency. Therefore pumice, a low-cost and naturally found porous material with lower specific surface area (2m2/gr), can be used as support material to reduce agglomeration of nZVI. Treatment efficiencies of pumice/nZVI packing (10:0 and 9:1 (w/w)) in column reactor for specified initial methylene blue concentrations (25, 50, 75 and 100 mg/L) were investigated in this study. Adsorption capacities of the adsorbents were calculated as 2.8 and 4.2 mg/g-adsorbent, respectively at 100 mg/L initial methylene blue concentration. Mixed bed column performed significantly better than its pumice-only counterpart for low initial concentrations. Thomas adsorption model was applied to experimental results with a moderate to high predictive power.Article Citation - WoS: 83Citation - Scopus: 90Packed Bed Column Dynamic Study for Boron Removal From Geothermal Brine by a Chelating Fiber and Breakthrough Curve Analysis by Using Mathematical Models(Elsevier Ltd., 2018) Recepoğlu, Yaşar Kemal; Kabay, Nalan; Yılmaz İpek, İdil; Arda, Müşerref; Yüksel, Mithat; Yoshizuka, Kazuharu; Nishihama, SyouheiIn this study, the performance of N-methyl-D-glucamine (NMDG) type functional group attached a novel boron selective chelating fiber adsorbent, Chelest Fiber GRY-HW, was investigated for boron removal from geothermal brine containing 10–11 mg B/L through a packed bed column. The effect of feed flow rate (Space Velocity, SV) on breakthrough capacity of Chelest Fiber GRY-HW was studied using various SV values (15, 20 and 30 h−1). The effect of SV on breakthrough capacity was particularly apparent when SV was decreased from 30 to 15 h−1. Yoon–Nelson, Thomas and Modified Dose Response (MDR) models were applied to the experimental data to estimate the breakthrough curves and model parameters such as rate constants and breakthrough times. The obtained results showed that the breakthrough curves were better described by Modified Dose Response (MDR) model than those described by Yoon-Nelson and Thomas models in each case. Also, the model estimations for adsorption capacity obtained by MDR model agreed well with the experimental results.Article Citation - WoS: 17Citation - Scopus: 19Effect of Operational Conditions on Separation of Lithium From Geothermal Water by ?-Mno2 Using Ion Exchange–membrane Filtration Hybrid Process(Taylor and Francis Ltd., 2018) Recepoğlu, Yaşar Kemal; Kabay, Nalan; Yoshizuka, Kazuharu; Nishihama, Syouhei; Yılmaz İpek, İdil; Arda, Müşerref; Yüksel, MithatA hybrid system coupling ion exchange and ultrafiltration (UF) was employed to separate lithium from lithium-spiked geothermal water. The effect of process parameters such as adsorbent type, adsorbent dosage, permeate flow rate, and replacement speeds of fresh and saturated adsorbents have been evaluated to determine the efficiency of the hybrid system. According to the results obtained using λ-MnO2 derived from spinel-type lithium manganese dioxide, the optimal operating conditions to separate lithium from geothermal water were found with powdery λ-MnO2 with an adsorbent concentration of 1.5 g adsorbent/L solution, replacement rates of fresh and saturated adsorbents of 6.0 mL/min, and a permeate flow rate of 5.0 mL/min. The ion exchange–UF hybrid system providing an advantage to work with very fine particles easily can be considered as a favorable process for the separation of lithium from geothermal water.