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Synthesis of Epoxy Resin From Linseed Oil and Development of New Bio-Based Films Using Calendula Officinalis L. Oil
No full textEpoxy resin thin films are widely used in applications such as anticorrosive coating materials, insulating and electronic packaging films, and adhesives; accordingly, research on new epoxy materials has become increasingly important. Developing new bio-based epoxy films or coatings is important to address this issue. This study synthesized epoxidized linseed oil (ELO) by epoxidation of linseed oil, and a novel bio-based matrix was formed with commercial epoxy resin (ER) at a weight ratio of 3:2. The characterization of ELO was performed using Fourier Transform Infrared Spectroscopy (FTIR), as well as by determining the iodine and epoxide groups. In addition, new films were formed by adding 1 %, 3 %, 5 %, 7 %, 10 %, and 15 % by weight Calendula officinalis L. oil (CldO). The effect of CldO on mechanical (thickness, tensile strength, and elongation at break), structural (Scanning Electron Microscopy (SEM) and FTIR), water barrier (WVP, water solubility, swelling), chemical resistance, antibacterial, and biodegradation properties was evaluated. ELO and CldO reduced the film's thickness. The film's water vapor permeability ratio (WVTR) was relatively low, ranging from 0.0153 g/(m2 center dot d) to 0.0661 g/(m2 center dot d). A 10 wt% CldO was selected as an appropriate ratio, especially regarding mechanical properties, water vapor permeability rate (WVPR), and opacity. Above 10 wt% CldO, tensile elongation sharply decreased, while water solubility and opacity significantly increased. Films containing CldO at 10 wt% and 15 wt % demonstrated enhanced antibacterial properties against certain pathogenic bacteria and biodegradation. In addition, all films showed resistance to 5 % NaCl, 3 % HCl, and 50 % ethanol solutions.The recent work was financially supported by the Selcuk University Scientific Research Foundation, Turkiye (Support project No: 24201027) .Selcuk University Scientific Research Foundation, Turkiye [24201027
Solid Particle Erosion Behaviors of Walnut Shell-Filled Acrylic-Styrene (Asa) and Polycarbonate/Acrylic-Styrene-Acrylate (Pc/Asa) Thermoplastic Blend Biocomposites
No full textKaragoz, Idris/0000-0002-2644-8511The aim of this study is to investigate the solid particle erosion behavior of walnut shell (WS)-filled acrylic-styrene-acrylate (ASA) and polycarbonate/acrylic-styrene-acrylate (PC/ASA) thermoplastic blend composites under various erosion conditions. Erosion resistance tests were conducted using Al2O3 particles (600 mu m, Mohs hardness 9) as erodent, at a velocity of 34 m/s, with impingement angles ranging from 30 degrees to 90 degrees. Test samples were subjected to these conditions for 24 s, and weight loss was measured to determine erosion rates. Key parameters such as density, hardness, and erosion coefficients were also evaluated. Composites with 10 wt% WS filler exhibited optimal performance, reducing erosion rates by up to 36.7% compared to unfilled PC/ASA blend. Macro and SEM imaging revealed the damage mechanisms, showing less material loss and better surface durability in WS-filled composites. This study demonstrates that incorporating WS into ASA and PC/ASA matrices not only improves erosion resistance but also aligns with the goal of sustainable material development. The results suggest that these composites could be highly effective in industries where materials are exposed to wear and tear from abrasive forces, such as in construction or automotive applications
The Influence of Two-Dimensional g-C3n4, Mxene, and Fe2O3 Additives on Tribofilm Formation in Mechanical Interfaces
No full textThis study investigated the effects of two-dimensional (2D) g-C3N4, MXene, and Fe2O3 additives on tribofilm formation in mechanical interfaces. Fe2O3 was synthesized using the hydrothermal method, g-C3N4 was prepared by the thermal melamine treatment, and MXene was obtained by etching the MAX phase. The nanoparticles were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy, and the wall thicknesses were found to be 171.5 nm, 77.6 nm, and 62.6 nm, respectively. Tribological tests were carried out under a constant 20 N load using engine oil with and without additives. Wear tests were evaluated by examining the friction coefficient, specific wear-rate, surface temperature, and wear scar morphology. Optimum performance was obtained at a nanoparticle concentration of 0.5 mg/ml. Adding Fe2O3, MXene, and g-C3N4 nanoparticles at this concentration reduced the friction coefficient by 21%, 23%, and 8%, respectively. Specific wear-rates were reduced by 29.6%, 32.4%, and 18.5%, respectively, while the surface temperature was decreased by 6.08%, 3.87%, and 3.32%, respectively. Among the additives, MXene showed the best performance as a wear inhibitor due to its ability to form stable tribofilm and enhance the lubrication performance. This study highlights the promising application of 2D nanomaterials in developing advanced lubricants for improved wear resistance and thermal stability.Karabuk UniversityScientific Research Projects Coordination Unit of Karabuk University [KBUEBAP-23-DS-116]This study was supported within the scope of the Project Numbered "KBUEBAP-23-DS-116" supported by the Scientific Research Projects Coordination Unit of Karabuk University. In addition, Karabuk University MARGEM laboratories were used
Effect of Microwave Pretreatment on Oil Agglomeration of Lignite Using Different Bridging Oils
No full textAbdelraheem, Mohamed Taha Osman/0000-0002-9674-2257This manuscript consists of two parts. In the first part, oil agglomeration experiments were carried out to enrich the lignite coal sample obtained from Tun ; ccedil;bilek underground mine using 4 different binding oils such as kerosene, mineral oil, diesel oil and vegetable waste oil. The experimental parameters such as pH, stirring speed, oil concentration and agglomeration time were investigated in detail. The best results were obtained with vegetable waste oil, mineral oil, diesel oil and kerosene, respectively. In the second part, the oil agglomeration tests (under conditions where optimum results were obtained in the first part) were performed on the lignite coal samples after microwave treatment at different powers and times. The microwave pretreatment results revealed that some mass loss occurred in the coal sample and the ash content of the coal increased. Fourier transform infrared spectrometer (FTIR) was applied for the investigation of the chemical structure differences of agglomerates
Effect of Pile Geometry and Soil Saturation Degree on Point Bearing Capacity for Bored Piles in Sands
No full textIn the present paper, an experimental study was conducted to determine the factors affecting the point bearing capacity of pile foundations constructed in dry and saturated sandy soils. Model piles were installed as reinforced concrete bored piles cast-in-situ. Model pile foundations of various geometries resting at different depths in homogeneous sand of different saturation degrees (%0-100) were loaded statically to failure. The test results showed that the bearing capacity of piles did not significantly affect by the loading rate. At most 10% difference was observed in pile bearing capacity when the loading rate was between 0.7 and 2.5 mm/min. Subsequently, the load bearing capacities of the piles were determined at a specified constant loading rate. The point and total capacities of the piles were measured separately in the experiments, then test results were compared with theoretical values. Pile point capacities provided from pile load tests are smaller than the theoretical values. The differences between experimental and theoretical results have been attributed to the Nq values. The Nq values not only dependent on the internal friction angle of the soil but also the saturation degree of the soil, the pile diameter, and the effective stress. Nq values decrease since the pile length/pile diameter ratio increases
Co+2/klor İleri Oksidasyon Prosesi Vasıtasıyla Bemacid Blue Giderimi, Reaktif Radikallerin Tespiti ve Kinetik Çalışmalar
No full textÇalışmada Bemacid Blue (BB) sentetik tekstil boyasının gideriminde oksidant olarak kullanılan klorun Co+2, Ultraviyole-C (UV-C) ve görünür ışık ile kombinasyonları oluşturularak en etkili proses seçilmiş ve optimizasyonu yapılmıştır. Deneyler sonucunda boya giderim verimi ve işletme maliyeti göz önüne alındığında Co+2/Klor prosesi seçilmiş ve C0: 50 mg/L BB (0.84mM), pH:3, klor: 0.8mM ve Co+2: 50µM 20 dk reaksiyon süresi optimum şartlarında %97.78 giderim verimine ulaşılmıştır. Proseste %46.1 katkı ile •OH en etkin ve baskın radikaldir, ancak reaktif klor radikallerinin (•Cl2-, •Cl ve •ClO (RCS – Reactive Chlorine Species)) %51.68 toplam katkı ile BB gideriminde etkin bir rol oynadığı belirlenmiştir. Optimum şartlarda gerçek tekstil atık suyu ile yapılan çalışmalar sonucunda, dalga boyu taramasında oluşan 1 ve 2 nolu ana piklerde sırasıyla %83.2 ve %88.6 oranında azalma gerçekleşerek etkin bir boya giderimi sağlanmıştır. Bununla birlikte, Behnajady–Modirshahla–Ghanbery (BMG) modeli için korelasyon katsayısı değeri (R2=0.9999), birinci ve ikinci derece modellerden daha yüksek olduğundan BB’nun Co+2/Klor prosesi ile giderimini açıklayan en iyi modeldir
Occurrence, Distribution, and Fate Evaluation of Endocrine Disrupting Compounds in Three Wastewater Treatment Plants With Different Treatment Technologies in Türkiye
No full textNowadays, two of the endocrine disrupting compounds (EDCs) in the group of alkylphenols (APs), nonylphenol (4-NP) and octylphenol (4-t-OP), have attracted great scientific and regulatory attention mainly due to concerns about their aquatic toxicity and endocrine disrupting activity. This paper investigated the occurrence, distribution behavior, fate, and removal of 4-NP and 4-t-OP in liquid and solid phases of three full-scale wastewater treatment plants (WWTPs) with different treatment technologies comparatively. In this context, (i) advanced biological WWTP, (ii) wastewater stabilization pond (WSP), and (iii) constructed wetland (CW) were utilized. In all three investigated WWTPs, the concentrations of 4-NP (219.9–19,354.4 ng/L) in raw wastewater were higher than those of 4-t-OP (13.9–2822.4 ng/L). Within the scope of annual average removal efficiencies, 4-NP was treated highly in advanced biological WWTP (93.5 %), while it was almost not treated in WSP (3.1 %) and treated with negative removal (0 %) in CW. While 4-t-OP was treated at a similar removal rate (93.5 %) to 4-NP in advanced biological WWTP, it was treated moderately in WSP (52.5 %) and very poorly in CW (12.4 %). It has been determined that the most important removal mechanism of both 4-NP and 4-t-OP in WWTPs is biodegradation, followed by sorption onto sewage sludge. According to the mass balance performed in advanced biological WWTP, the biodegradation rates for 4-NP and 4-t-OP were found to be 70.4 % and 86.6 %, respectively, while the sorption onto sewage sludge were determined to be 23.3 % and 6.8 %. One of the critical findings obtained within the scope of the study is that while the concentrations of both metabolites, especially 4-NP, in wastewater and sewage sludge, decreased considerably under aerobic conditions, on the contrary, their concentrations increased significantly under anaerobic conditions. Both compounds were detected at higher concentrations in primary sludge compared to secondary sludge in advanced biological WWTP, while in WSP, they were determined at higher concentrations in anaerobic stabilization pond sludge compared to facultative stabilization pond sludge. Besides, it was also determined that the sorption behavior of these alkylphenols is much more dominant than desorption. © 2024 Elsevier B.V
Determination by Numerical Modeling of Stress-Strain Variations Resulting From Gallery Cross-Section Changes in a Longwall Top Coal Caving Panel
No full textAs a major pillar of global energy production, coal mining requires continuous advancements in efficiency to contribute to the broader goal of energy sustainability, all the while the shift towards more sustainable energy sources is underway. Mechanized excavation systems employed in underground coal mines, particularly within the longwall mining method, enable high-tonnage coal production. The Longwall Top Coal Caving (LTCC) method, one of the longwall mining techniques, has been developed for the effective extraction of coal from thick coal seams. However, as mining operations delve deeper, various complex issues, such as gallery cross-sectional variation, emerge. Gallery cross-sectional variation can increase the risk of collapse by affecting the stress distribution in the rock mass, posing a threat to worker safety. This study centers on the numerical modeling and analysis of gallery cross-sectional variation in the Ömerler underground mine, operated by the Turkish Coal Enterprises (TKI), West Lignite Enterprise (GLI). To achieve this objective, an extensive database was established through field and laboratory rock mechanics studies. This database was then utilized in the Fast Lagrangian Analysis of Continua 3D (FLAC3D) (v6.0) program to simulate the cross-sectional variations of the A6 panel in the Ömerler underground mine. The numerical simulation results provide valuable insights into the secondary stress-deformation changes associated with gallery cross-sectional variation
Investigation of the Enrichment of Sulphide Copper Ore by Agloflotation
No full textIn this thesis, the enrichment of sulphide copper ore by aggloflotation was examined. The sulphide copper sample used was obtained from Gökırmak copper mine (Acacia Mining Enterprises). This master's thesis consists of two stages. In the first stage, classical flotation experiments of sulphide copper ore were carried out. In the experiments, optimum pH, amount of dispersant, collector type and amount and frother amount were investigated. In the second stage, agloflotation experiments were carried out. In the aggloflotation stage, the agglomerates agglomerated by oil agglomeration were floated by flotation. Agglomeration of fine-sized ore was carried out under the optimum conditions determined in the first flotation stage. Then, these agglomerates were transferred to the flotation cell and frother was added, thus the agglomerates were floated and the aggloflotation experiments were completed. In oil agglomeration, the amount and type of oil and mixing speed and time are the parameters investigated. In flotation experiments, under optimum conditions, the concentrate was obtained with 4.82% Cu and 73.29% yield (pH=11; 100 g/t 3418A; 50 g/t sodium silicate; 50 g/t MIBC). In agloflotation, the %Cu of chalcopyrite concentrates obtained from waste oil reaches 5.69%, while the yield varies between 58.75% and 48.46%. By using kerosene, the concentrate containing 6.1% Cu was obtained with a yield of 53.43%. To determine the effect of mixing speed on the aggloflotation of chalcopyrite, experiments were carried out by keeping the speed constant at 1000 rpm and changing the agglomeration speed during the flotation stage of aggloflotation. The highest copper contents of the obtained concentrates were 6.53% and 6.10% for domestic waste oil and kerosene, respectively. The recovery values of the concentrates having highest recovery obtained from domestic waste oil and kerosene are 68.65% and 77.01%, respectively.Bu tez çalışmasında sülfürlü bakır cevherinin agloflotasyon ile zenginleştirilebilirliği incelenmiştir. Deneylerde kullanılan sülfürlü bakır numunesi, Gökırmak bakır madeniden temin edilmiştir (Acacia Maden İşletmeleri). Bu yüksek lisans tezi iki aşamadan oluşmaktadır. İlk aşamada sülfürlü bakır cevherinin klasik flotasyon deneyleri yapılmıştır. Deneylerde optimum pH, dağıtıcı miktarı, toplayıcı türü ve miktarı ile köpürtücü miktarı araştırılmıştır. İkinci aşamada ise agloflotasyon deneyleri yapılmıştır. Agloflotasyon aşamasında, yağ aglomerasyonu ile aglomere edilen aglomeratlar flotasyon ile yüzdürülmüştür. İnce boyuttaki cevherin aglomerasyonu ilk aşama flotasyonda belirlenen optimum koşular altında gerçekleştirilmiştir. Daha sonra bu aglomeratlar flotasyon hücresine transfer edilerek köpürtücü ilavesi yapılmış böylece aglomeratların yüzdürülmesi ile agloflotasyon deneyleri tamamlanmıştır. Yağ aglomerasyonunda yağ miktarı ve tipi ile karıştırma hızı ve süresi araştırılan parametrelerdir. Flotasyon deneylerinde optimum şartlarla %4.82 Cu tenörlü konsantre %73.29 verimle kazanılmıştır (pH=11; 100 g/t 3418A; 50 g/t sodyum silikat; 50 g/t MIBC). Agloflotasyonda, atık yağ ile elde edilen kalkopirit konsantrelerinin Cu tenörleri %5.69 ulaşırken verimi %58.75 ile %48.46 arasında değişmektedir. Gaz yağı kullanarak ise %6.1 Cu içerikli konsantre %53.43 verimle kazanılmıştır. Karıştırma hızının kalkopiritin agloflotasyonuna etkisinin belirlenmesi için agloflotasyonun flotasyon aşamasında hız 1000 dev/dak'da sabit tutularak, aglomerasyon hızı değiştirilerek deneyler yapılmıştır. Elde edilen konsatrelerin en yüksek bakır içerikleri evsel atık yağ ve gazyağı için sırasıyla %6.53 ve %6.10 olmuştur. Evsel atık yağ ve gaz yağı ile elde edilen en yüksek verimli konsantrelerin verim değerleri sırasıyla %68.65 ve %77.01'dir
Agrega Gradasyonundaki Değişimlerin Aşınma Tabakasında Kullanılan Bitümlü Sıcak Karışımların Mekanik Özelliklerine Olan Etkilerinin İncelenmesi
No full textTürkiye’de bitümlü karışımın kullanılacağı tabakaya göre hangi gradasyon özelliklerine sahip olması gerektiği Karayolu Teknik Şartnamesinde belirtilmiştir. Bu çalışmada, şartnamede aşınma tabakası için tanımlanan Tip-1 gradasyon zarfındaki alt, orta ve üst limit değerlerinin yanı sıra alt ve üst limitlerin belirli oranda ötelenmesiyle oluşturulan beş farklı agrega gradasyonunun bitümlü karışımların mekanik özellikleri üzerindeki etkilerinin araştırılması amaçlanmıştır. Belirlenen beş gradasyon ile hem gradasyon zarfı dahilindeki değişimlerin etkisi hem de gradasyon zarfının genişleme potansiyeli incelenmiştir. Bu amaç doğrultusunda farklı agrega gradasyonları ile oluşturulan bitümlü karışımlarla Marshall tasarımları yapılmıştır. Test sonuçlarına göre agrega gradasyonu inceldikçe karışımın optimum bitüm ihtiyacı artmıştır. Gradasyon inceldikçe, optimum bitüm oranındaki bitümle dolu boşluk oranının (Vf) ve agregalar arasındaki boşluk yüzdesinin (VMA) arttığı, birim ağırlığın (Dp) azaldığı tespit edilmiştir. Aynı zamanda, Tip-1 için tanımlanan gradasyon zarfının genişleme potansiyelinin olabileceği görülmüştür.