Ahmetoğlu, Çekdar Vakıf
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Vakıfahmetoğlu, Çekdar
Vakıf Ahmetoğlu, Çekdar
Vakıfahmetoğlu, Ç.
Vakif Ahmetoglu, Cekdar
Vakifahmetoglu, Cekdar
Vakifahmetoglu, C.
Ahmetoglu, Cekdar Vakif
Vakıf Ahmetoğlu, Çekdar
Vakıfahmetoğlu, Ç.
Vakif Ahmetoglu, Cekdar
Vakifahmetoglu, Cekdar
Vakifahmetoglu, C.
Ahmetoglu, Cekdar Vakif
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Email Address
cekdarvakifahmetoglu@iyte.edu.tr
Main Affiliation
03.09. Department of Materials Science and Engineering
Status
Former Staff
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Sustainable Development Goals
1NO POVERTY
0
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2ZERO HUNGER
0
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3GOOD HEALTH AND WELL-BEING
0
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4QUALITY EDUCATION
0
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5GENDER EQUALITY
0
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6CLEAN WATER AND SANITATION
5
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7AFFORDABLE AND CLEAN ENERGY
7
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8DECENT WORK AND ECONOMIC GROWTH
3
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
17
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10REDUCED INEQUALITIES
0
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11SUSTAINABLE CITIES AND COMMUNITIES
0
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
7
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13CLIMATE ACTION
7
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14LIFE BELOW WATER
3
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15LIFE ON LAND
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
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17PARTNERSHIPS FOR THE GOALS
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Documents
69
Citations
2276
h-index
27
Documents
67
Citations
2069
Scholarly Output
53
Articles
40
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38878/18450
Supervised MSc Theses
9
Supervised PhD Theses
3
WoS Citation Count
670
Scopus Citation Count
718
Patents
0
Projects
3
WoS Citations per Publication
12.64
Scopus Citations per Publication
13.55
Open Access Source
34
Supervised Theses
12
| Journal | Count |
|---|---|
| Ceramics International | 6 |
| Journal of the American Ceramic Society | 5 |
| Journal of the European Ceramic Society | 4 |
| Open Ceramics | 4 |
| Icarus | 2 |
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53 results
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Now showing 1 - 10 of 53
Review Citation - WoS: 44Citation - Scopus: 48Review on Polymeric, Inorganic, and Composite Materials for Air Filters: From Processing To Properties(John Wiley and Sons Inc, 2021) Henning,L.M.; Abdullayev,A.; Vakifahmetoglu,C.; Simon,U.; Bensalah,H.; Gurlo,A.; Bekheet,M.F.Particulate and gaseous air pollutants pose a threat to human health and contribute to climate change. By today, air filters, stationary and portable, are markedly improved and can often provide innocuous air pollution levels. After introducing the classification and standards on air filters, the influence of the processing route and its parameters on the resulting air filter properties and consequently its performance are discussed. Numerous tools are presented to adjust structural properties such as fiber or pore diameter, specific surface area, surface charge, hydrophilicity, or photocatalytic activity to achieve the desired performance in terms of high filtration efficiencies, sufficient mechanical stability, regeneration eligibility, antimicrobial and optical properties. In particular, inorganic and composite materials as well as nonfibrous structures are covered, which are currently holding an outsider position in an air filter community dominated by polymeric materials and fibrous structures. © 2021 The Authors. Advanced Energy and Sustainability Research published by Wiley-VCH GmbH.Article Citation - WoS: 18Citation - Scopus: 22Effect of Fomes Fomentarius Cultivation Conditions on Its Adsorption Performance for Anionic and Cationic Dyes(American Chemical Society, 2022) Henning, Laura M.; Simon, Ulla; Abdullayev, Amanmyrat; Schmidt, Bertram; Pohl, Carsten; Nunez Guitar, Tamara; Ahmetoğlu, Çekdar Vakıf; Meyer, Vera; Bekheet, Maged F.; Gurlo, AleksanderLab-cultivated mycelia of Fomes fomentarius (FF), grown on a solid lignocellulose medium (FF-SM) and a liquid glucose medium (FF-LM), and naturally grown fruiting bodies (FF-FB) were studied as biosorbents for the removal of organic dyes methylene blue and Congo red (CR). Both the chemical and microstructural differences were revealed using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, zeta potential analysis, and scanning electron microscopy, illuminating the superiority of FF-LM and FF-SM over FF-FB in dye adsorption. The adsorption process of CR on FF-LM and FF-SM is best described by the Redlich-Peterson model with β constants close to 1, that is, approaching the monolayer Langmuir model, which reach maximum adsorption capacities of 48.8 and 13.4 mg g-1, respectively, in neutral solutions. Adsorption kinetics follow the pseudo-second-order model where chemisorption is the rate-controlling step. While the desorption efficiencies were low, adsorption performances were preserved and even enhanced under simulated dye effluent conditions. The results suggest that F. fomentarius can be considered an attractive biosorbent in industrial wastewater treatment and that its cultivation conditions can be specifically tailored to tune its cell wall composition and adsorption performance.Article Citation - WoS: 37Citation - Scopus: 39Polymer-Derived Ceramic Adsorbent for Pollutant Removal From Water(John Wiley and Sons Inc., 2018) Zeydanlı, Damla; Akman, Süleyman; Ahmetoğlu, Çekdar VakıfPolymer-derived ceramic components (SiOC, sample W) were produced from preceramic polymer mixture and a catalyst. After curing and pyrolysis, some of the samples etched by hydrofluoric acid to obtain carbonaceous SiOC (C-rich SiOC, sample W-HF). W and W-HF were tested as an adsorbent material to remove both heavy-metal ions (Cr (III), Pb (III), and Cd (II)) and cationic dyes (Methylene Blue (MB), Rhodamine B (RB), and Crystal Violet (CV)) from aqueous solutions. HF-treated high surface area SiOC samples had quite high adsorption affinity for cationic dyes. According the Langmuir isotherm model the maximum dye uptake values were found to be around to 50 mg/g for sample W, whereas those for sample W-HF ranged from 104 to 186 mg/g. Regeneration studies were conducted both by heat treatment and leaching, high recovery yields (always above 97%) of MB adsorption were obtained.Article Citation - WoS: 7Citation - Scopus: 7Hydrothermal Synthesis of Potassium–sodium Niobate Powders(Wiley, 2022) Pişkin, Cerem; Karacasulu, Levent; Ischia, Gloria; Bortolotti, Mauro; Ahmetoğlu, Çekdar VakıfPotassium–sodium niobates (KxNa1−xNbO3, 0 < x < 1, KNN) were hydrothermally synthesized under varying alkaline ratios (K+/Na+), total hydroxide concentration, reaction temperature, and time. Compositional surveys were developed by using Rietveld analyses derived quantitative volume fractions. The data demonstrated that phase pure KNN synthesis can be achieved by reacting the niobium source with the hydroxide solution having 6 M total hydroxide concentration, cation ratio (K+/Na+) of above 6 at temperatures ≥200°C for 24 h. Dissolution–precipitation events through intermediate products including hexaniobates were postulated as a plausible formation mechanism. It was shown also that the single-phase KNN approaching the morphotropic phase boundary (MPB) could be obtained by further incorporation of sodium ions into the crystal via post-annealing at 800°C/2 h, following the hydrothermal synthesis.Article Citation - WoS: 28Citation - Scopus: 33Cold Sintering as a Promising Isru Technique: a Case Study of Mars Regolith Simulant(Elsevier, 2023) Karacasulu, Levent; Karl, David; Gurlo, Aleksander; Ahmetoğlu, Çekdar VakıfMars regolith simulant (MGS-1) was densified for the first time via a cold sintering process (CSP) as a novel in-situ resource utilization (ISRU) concept. The technique comprises the utilization of NaOH solution as a liquid media during the densification of simulant powder with <100 μm particle size. In as short as 30 min, with the increase in the NaOH concentration (from 3 M to 10 M) and processing temperature (from 150 °C to 250 °C), the relative densities of the regolith compacts and the mechanical properties were enhanced. The artifacts produced with Mars regolith simulant powder at 250 °C using 10 M NaOH solution yielded a relative density of around 88% and compressive strength reaching ∼45 MPa.Article Citation - WoS: 103Citation - Scopus: 110Cold Sintering of Ceramics and Glasses: a Review(Elsevier Ltd., 2020) Ahmetoğlu, Çekdar Vakıf; Karacasulu, LeventTraditionally ceramic artifacts are processed at high temperatures (> 1000 degrees C) by classical sintering techniques such as solid state, liquid phase and pressure-assisted sintering. Recently, inspired from the geology, novel sintering approaches that allow the densification of ceramic components at relatively low temperatures <= 400 degrees C have been proposed. While initial efforts for such low temperature densification concept were developed in the mid-70s, the topic has become increasingly prominent in the last decade. Currently, these low temperature methods can be classified into four main groups: (i) hydrothermal reaction sintering (HRS), (ii) hydrothermal hot pressing (HHP), (iii) pressure-assisted densification techniques: room-temperature densification (RTD), cold sintering (CS), warm press (WP), and finally no-pressure assisted method called (iv) reactive hydrothermal liquid phase densification (rHLPD). Above named techniques are commonly assisted by an aqueous solution used as either reactant or transient liquid phase to assist densification. Starting from the background in traditional sintering processes, this review aims to explore in depth the existing literature about low temperature densification approaches along with their advantages & disadvantages, and probable application areas.Doctoral Thesis Production and Applications of Si-Based Aerogels(01. Izmir Institute of Technology, 2025) Erdemir, Öykü İçin; Ahmetoğlu, Çekdar VakıfBu tez, Si-bazlı polimerik ve seramik aerojellerin ve kompozit yapılarının polimer türevli seramik (polymer derived ceramic, PDC) yaklaşımıyla üretimini ve uygulamalarını araştırmaktadır. Polimerik, hibrit ve seramik yapıdaki saf aerojeller ve köpük-aerojel kompozitleri, işleme-yapı-özellik ilişkileri açısından derinlemesine analiz edilmiştir. İlk bölüm aerojeller, PDC'ler, motivasyon ve hedeflere genel bir bakış sunmaktadır. 2. Bölüm, ortam basıncında kurutma (ambijeller) ve CO2 süperkritik kurutma yoluyla kolayca temin edilebilen bir polisiloksan polimeri kullanılarak üretilen SiOC ambi/aerojellerinin tasarımı ve performansına ilişkin araştırmayı sunmaktadır. Bu malzemeler, oda sıcaklığında (0,046 W·m–1·K–1) ve 500 °C'de (0,073 W·m–1·K–1) düşük ısıl iletkenlikle birlikte umut verici yağ emilimi (3,1 g·g–1'e kadar) ve su temizleme performansı sergilemiştir. Bölüm 3, ticari yalıtım panellerine kıyasla 1200 °C'ye kadar bütan meşalesi altında üstün yalıtım ve mekanik özelliklerini koruyabilen, çeşitli formlara işlenebilir, yüksek gözenekli aerojel monolitlerinin üretim fizibilitesini gösteren SiOC köpük-aerojel kompozit yaklaşımını ele almaktadır. Bölüm 4, monolitik hibrit ambi/aerojellerin geliştirilmesini inceleyerek, yağ/organik çözücü temizliği için potansiyellerini vurgulamaktadır. Bu aerojeller, yağ için 13 g·g–1'e ve çözücüler için 11 g·g–1'e kadar ulaşan yüksek sorpsiyon kapasiteleri göstermektedir ve organik çözücülerle birden fazla rejenerasyon döngüsü boyunca kararlı sorpsiyon sağlamaktadır. Bölüm 5, yüksek ve düşük sıcaklıklarda olağanüstü termal yönetim elde etmek için SiOC köpüğü ve silika aerojeli birleştiren inorganik kompozitlerin tasarımını incelemektedir. Genel olarak, Si bazlı polimerik ve seramik aerojeller, düşük termal iletkenlik, verimli termal yalıtım, yüksek sıcaklık stabilitesi ve atık su arıtımı dahil olmak üzere umut verici çok işlevli özellikler sergilemiştir.Article Citation - WoS: 11Citation - Scopus: 13Magnesium-Ion Battery Anode From Polymer-Derived Sioc Nanobeads(Wiley, 2023) Guo, Wuqi; Kober, Delf; Gurlo, Aleksander; Bekheet, Maged F.; İçin, Öykü; Ahmetoğlu, Çekdar VakıfTin-containing silicon oxycarbide (SiOC/Sn) nanobeads are synthesized with different carbon/tin content and tested as electrodes for magnesium-ion batteries. The synthesized ceramics are characterized by thermogravimetric-mass spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, N2 sorption analysis, scanning electron microscope, energy-dispersive X-ray, and elemental analysis. Galvanostatic cycling tests, rate performance tests, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) tests, and ex situ XRD measurements are conducted. Results of battery performance tests present a high capacity of 198.2 mAh g-1 after the first discharging and a reversible capacity of 144.5 mAh g-1 after 100 cycles at 500 mA g-1. Excellent rate performance efficiency of 85.2% is achieved. Battery performances in this research are influenced by surface area, and tin contentof the SiOC/Sn nanobeads. EIS, CV tests, and ex situ XRD measurements reveal that higher surface area contributes to higher capacity by providing more accessible Mg2+ ion storage sites and higher rate capability by improving the diffusion process. Higher Sn content increases battery capacity through reversible Mg-Mg2Sn-Mg alloying/dealloying process and improves the rate performances by increasing electrical conductivity. Besides, SiOC advances cycling stability by preventing electrode collapse and enhances the capacity due to higher surface capacitive effects. SiOC nanobeads containing Sn nanoparticles are synthesized and tested as anode for magnesium-ion batteries. The anodes show high performance with reversible capacity of 144.5 mAh g-1 after 100 cycles at 500 mA g-1 and excellent rate performance efficiency of 85.2% from 50 to 500 mA g-1.imageMaster Thesis Optimisation of Organic Phase Pre-Neutralisation Stage in Purification Studies With Solvent Extraction for Mhp (mixed Hydroxide Precipitate) Produced From Gördes Laterite Ore and Investigation of Its Effect on Extraction(01. Izmir Institute of Technology, 2021) Kaya, Ezgi; Ahmetoğlu, Çekdar VakıfIntermediate products such as MHP (Mixed Hydroxide Precipitate) are processed by solvent extraction which is a continuous process in industry for obtaining final product such as nickel metal or nickel sulphate. Nickel is used essentially in stainless steel industry and cobalt is used in super alloys. Both metals are used in lithium-ion battery technologies especially electrical vehicles. A preliminary stage of solvent extraction process is called as pre-neutralisation and it is based on partial neutralisation of the acidic organic reactant to prevent pH fluctuations in extraction due to the H+ ions release aqueous phase, and it provides an exchange mechanism to enable loading of the metals to the organic phase. In this thesis study, it is aimed to optimise the organic phase pre-neutralisation percent in further purification treatment of MHP leach solution (PLS-Pregnant Leach Solution) from Gordes nickel laterites and investigate its effect on extraction by D2EHPA and Cyanex 272 organic reactants. NaOH and Na2CO3 solutions were used in pre-neutralisation with 35%, 40% and 45% in D2EHPA and 30%, 35% and 40% in Cyanex 272. The optimum pre-neutralisation results were found as 35% for D2EHPA and 30% for Cyanex 272.Article Citation - WoS: 23Citation - Scopus: 23Hot Air Permeable Preceramic Polymer Derived Reticulated Ceramic Foams(American Chemical Society, 2020) de Mello Innocentini, Murilo Daniel; Marsola, Gabriel Antonio; Orlandi Lasso, Paulo Renato; Soraru, Gian Domenico; Semerci, Tuğçe; Vakıfahmetoğlu, ÇekdarOpen and partially closed cell polymer derived ceramic, specifically silicon oxycarbide, foams were produced from commercially available polyurethane (PU) foams through the replica technique combined with the preceramic polymer pyrolysis route. The focus was directed on the role of PU morphology (cell size and open/partially closed cells), synthesis parameters (cross-linking temperature and time), and type of the polysiloxane precursors for fine-tuning the microstructural features of the resulting ceramic foams and their eventual effect on the fluid dynamic/mechanical properties. Consequently, ceramic foams having dense/hollow struts with/without hierarchical porosity were able to be manufactured and characterized in detail. The average total porosity including all compositions was above 95%, the maximum surface area was found to be reaching 79 m(2).g(-1), and the room temperature permeability measurements indicated a wide range for k(1) (0.28 x 10(-9)-11.48 x 10(-9) m(2)) and k(2) (0.34 x 10(-5)-54.17 x 10(-5) m) according to the selected PU substrate. Hot air permeation tests showed that the foams were stable up to 700 degrees C without any loss of functionality. Accordingly, they are envisioned to be employed as reusable air filtration device parts for pollutants (viruses, bacteria, dust, etc.), catalytic supports, and filter components for reactions occurring in aggressive environments.