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Öğe Biyoatıklardan elde edilen aktif karbonlar ile sulu çözeltilerden amoksisilin adsorpsiyonunun izoterm ve kinetik çalışmaları(Malatya Turgut Özal Üniversitesi, 2024) Yavuz, Bahar; Korkmaz, Aydan AksoğanSon yıllarda, antibiyotikler, tıptaki kullanımlarının yanı sıra tarım ve hayvancılıkta da sıklıkla kullanılmaktadır. Özellikle amoksisilin (AMX), geniş spektrumlu bir ?-laktam antibiyotik olarak, birçok Gram-pozitif organizma ve sınırlı sayıda Gram-negatif organizmaya karşı etkili bir antibiyotiktir. AMX stabil ve suda kolayca bozulmadığından atık sular, toprak ve sedimanlarda yaygın bir şekilde bulunmaktadır. Antibiyotik bu içeren suların, insan ve çevre sağlığının korunması için etkin bir işlemle arıtılması gerekmektedir. Bu tez çalışması kapsamında; domates, biber ve patlıcan gibi bol miktarda bulunan lignoselülozik tarımsal atıklardan sentezlenen aktif karbonların morfolojik, yapısal, kimyasal ve adsorpsiyon özellikleri araştırılmıştır. İki aşamalı kimyasal aktivasyon yöntemi, N2 atmosferi altında yapılmıştır. İlk olarak, biyokütlelerin 500°C'de 1 saat süreyle karbonizasyonu, ardından, farklı KOH emprenye oranlarında (1:1, 1:2, 1:3) 800°C'de 1 saat süresince aktivasyon işlemi gerçekleştirilmiştir. Gözenekli aktif karbon malzemelerin karakterizasyonu elementel analiz (C, H, N, S), X-Ray Difraktometre (XRD), Fourier Dönüşümlü Kızılötesi Spektroskopisi (FTIR), Brunauer-Emmett-Teller (BET) ve Tarama Elektron Mikroskobu (SEM) teknikleriyle yapılmıştır. Aktif karbonların adsorban özelliklerinin belirlenmesi için amacıyla farklı konsantrasyonlardaki sulu çözeltilerden amoksisilin giderimi batch adsorpsiyon yöntemiyle araştırılmıştır. 1:3 biyokütle/KOH ağırlık oranına sahip aktif karbonlar en yüksek yüzey alanlarına (2070-2254 m²/g) sahip olduğundan adsorpsiyon deneylerinde bu örnekler kullanılmıştır. Adsorpsiyon mekanizması, Langmuir ve Freundlich izotermleriyle; kinetikler analizi ise, Partikül İçi Difüzyon, Yalancı Birinci Derece ve Yalancı İkinci Derece modelleriyle aydınlatılmıştır. Adsorpsiyon mekanizması için en uygun model Langmuir izotermi, adsorpsiyon kinetiği için en uygun model ise Yalancı İkinci Derece model olarak belirlenmiştir. Amoksisilinin sulu çözdeltilerden uzaklaştırılması %96.4 başarıyla gerçekleşmiş olup, 50 ppm başlangıç konsantrasyonunda ve 75 dakika temas süresinde maksimum Langmuir adsorpsiyon kapasitesi 330.60 mg/g olarak hesaplanmıştır. Sonuç olarak, tarımsal atıklardan elde edilen aktif karbonun, çevresel sürdürülebilirlik ve su kalitesinin korunması açısından stratejik olarak önemli olduğuna karar verilmiştir.Öğe Preparation and characterization of activated carbon from tomato, pepper, and eggplant wastes by two-step KOH activation(Taylor & Francis Inc, 2026) Yavuz, Bahar; Aksogan Korkmaz, Aydan; Kaya, Harun; Guler, Seher; Atalay, Funda ErsoyThis study investigates the morphological, structural, and chemical properties of activated carbons synthesized from common lignocellulosic agricultural wastes such as tomato, pepper, and eggplant residues. A two-step chemical activation method was employed. In the first step, the biomass was carbonized at 500 degrees C for 1 h to produce biochar. In the second step, the activation process was conducted at 800 degrees C for 1 h using different biochar:KOH impregnation ratios (1:1, 1:2, 1:3). The surface area of the resulting porous carbonaceous materials was determined by BET analysis, while their morphological features were examined by Scanning Electron Microscopy (SEM). Structural and chemical properties were characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The highest surface area values of activated carbons (2070-2254 m2/g) were obtained with a biochar:KOH weight ratio of 1:3. SEM images revealed the formation of a well-developed porous structure as a result of oxidation-reduction reactions. XRD analysis indicated the presence of graphite-like amorphous structures. FTIR spectra confirmed the presence of various surface functional groups, including C = C, C = O, C-H, C-C, and C-O. These findings demonstrate that widely available and low-cost agricultural wastes can serve as effective, environmentally friendly, and sustainable precursors for the production of activated carbon.Öğe Sustainable approach to dye adsorption: hemp-based activated carbon as an effective adsorbent(Taylor & Francis Ltd, 2025) Toptas, Yeliz; Yavuz, Bahar; Korkmaz, Aydan Aksogan; Onal, YunusIn industry, the use of dyes that threaten human health is increasing day by day. RB 19 (Reactive Blue 19, Remazol brilliant blue R), one of the most common dyes that adversely affect natural life, is the subject of this article. In this article, the waste parts of the hemp plant (root, stem and other) were evaluated for use in scientific studies. Hemp wastes were carbonised at 500 degrees C at a heating rate of 10 degrees C/min for 1 hour in the N2 atmosphere. Chemical activation was then carried out with 1:4 potassium hydroxide (KOH) at 800 degrees C under the same conditions. Activated carbon (AC) used as an adsorbent was characterised by elemental analysis (73.3% C, 0.3% H, 0.46% N, 0.02% S and 25.92% O), XRD, SEM, BET and FT-IR analysis. Activated carbon (AC) with 850 mu m size, 1858.70 m2/g surface area was obtained by chemical activation of carbonised hemp waste with KOH. SEM images showed that the activated carbon is structurally similar to a honeycomb. Kinetic parameters were analysed with six different equations (Intra Particle Diffusion, Pseudo First, Pseudo Second, Elovich, Avrami, Bangham) and adsorption mechanism with eight different equations (Henry, Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Koble-Corrigan, Flory-Huggins, Harkin-Jura). According to the calculated diffusion coefficient (19.299), it is concluded that diffusion is externally controlled. The Intra-Particle Diffusion constant (75.34) indicated that the outer adsorption layer of activated carbon was thick. When the correlation coefficients of the equations were examined according to the kinetic analysis results, the highest correlation coefficient was observed in the Pseudo-First kinetic model for all temperatures. However, it was determined that it also fits the Bangham and Avrami models. Since Bangham and Avrami models have high regression coefficients (0.96-0.99), it can be said that adsorption also fits these models. Also, the negative Gibbs Free Energy values indicate that adsorption can occur spontaneously and is thermodynamically favourable.Öğe Synthesis of activated carbons from tomato, pepper, and eggplant residues for water purification: Insights from kinetic and thermodynamic analyses(Elsevier, 2026) Yavuz, Bahar; Korkmaz, Aydan AksoganThe widespread occurrence of pharmaceutical contaminants such as amoxicillin (AMX) in aquatic environments poses a significant threat to ecosystems and public health. Transforming abundant agricultural waste into functional adsorbent materials presents a sustainable and economical solution to this growing environmental challenge. This study investigates the synthesis and application of activated carbons (ACs) derived from agricultural waste residues of tomato, pepper, and eggplant for the efficient removal of amoxicillin (AMX) from aqueous solutions. The ACs were prepared via a two-step chemical activation process using KOH and characterized through elemental analysis, BET surface area measurements, zeta potential, Raman, FT-IR, XPS, and SEM imaging. The results revealed high surface areas (2069-2254 m2/g) and a predominance of mesoporous structures, with tomato-derived activated carbon (TAC) exhibiting the highest mesopore area (1780.31 m2/g). Batch adsorption experiments demonstrated a maximum AMX removal efficiency of 94.6 % under optimal conditions (50 mg/L initial concentration, 310 K, 60 min contact time). The Langmuir isotherm model provided the best fit for the adsorption data, indicating monolayer coverage with a maximum adsorption capacity of 370.37 mg/g for TAC. Kinetic studies confirmed that the adsorption process adhered to the Pseudo-Second-Order model, suggesting chemisorption as the rate-limiting step. Thermodynamic analysis revealed negative values for Gibbs free energy (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees), confirming the spontaneity, exothermic nature, and decreased randomness of the adsorption process. These findings highlight the potential of agricultural waste-derived ACs as sustainable and cost-effective adsorbents for mitigating pharmaceutical contaminants in water, providing significant environmental and economic benefits.Öğe The viability of biochar as an alternative low-emission fuel from waste biomass carbonization(Taylor & Francis Ltd, 2026) Yavuz, Bahar; Aksogan Korkmaz, AydanEnergy demand in developing countries is primarily met by fossil fuels, which are limited and environmentally harmful, releasing SOx, NOx, and CO2. Renewable alternatives such as biomass are essential for sustainable energy production. This study investigates the production of biochar via pyrolysis of agricultural wastes (pepper, tomato, and eggplant) at 500 degrees C for one hour (heating rate: 10 degrees C/min, N2 flow: 150 ml/min). It evaluates their potential as clean solid fuels. Tomatoes produced the highest char yield (38.33%), whereas eggplant and pepper generated the highest liquid (33.33%) and gas (45%) fractions, respectively, indicating feedstock-dependent product distributions. The resulting biochars exhibited low nitrogen (0.92%) and sulfur (0.06%) contents, high carbon content (66.58%), and high calorific value (25.52 MJ/kg), highlighting their suitability as environmentally friendly energy carriers. These findings demonstrate that agricultural residues can be efficiently converted into biochars with both environmental and energy benefits, providing a promising route for renewable fuel production and sustainable waste valorization. The study emphasizes the potential of biochar as a clean, high-energy solid fuel, helping reduce emissions and advancing circular economy objectives.
