Yazar "Kaya, Mehmet" seçeneğine göre listele

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    Çeşitli Katyon Değiştirilmiş ve Sütunlanmış Artvin Bentonitlerinin Karakterizasyonu ve Seçilmiş Bir Organik Reaksiyonda Katalizör Olarak Kullanılmaları
    (2020) Tabak, Ahmet; Caglar, Bulent; Kaya, Mehmet
    Bu çalışmada Artvin ham bentonitinin, bazı metal katyonları (Fe3+ ve Cu2+) değiştirilmiş ve Fe- ve Alsütunlanmış türevlerinin benzaldehitin 2,3-bütandiol ile asetalleşme reaksiyonundaki katalitik aktiviteleri araştırıldı. Bu katalizörlerin yapısal ve fizikokimyasal özellikleri X–ışınları toz kırınım (XRD), taramalı elektron mikroskobu (SEM), Fourier transform infrared (FTIR), ve yüzey alanı ölçüm teknikleri yardımıyla aydınlatılmıştır. Cu-bentonit ve Al sütunlu-bentonit katalizörlü reaksiyonlarda verimin çok az olduğu buna karşın Fe-bentonit ve Fe-sütunlu bentonit katalizörlerinin kullanıldığı tepkimelerde ise sırasıyla % 60 ve % 63 verimle asetalleşme reaksiyonu gerçekleştiği tespit edilmiştir. Bu çalışma ülkemizin önemli yerli kaynaklarından birini teşkil eden Artvin bentonitinin modifiye edilmesiyle organik reaksiyonları katalizleyebildiğini ve bu ürünlerin küçük ölçekte ve endüstriyel proseslerdeki reaksiyonlar için kullanılabileceğini ortaya koymuştur.
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    Öğe
    Preparation and characterization of a novel activated carbon component via chemical activation of tea woody stem
    (Springer, 2019) Tabak, Ahmet; Sevimli, Kadir; Kaya, Mehmet; Caglar, Buelent
    The novel activated carbon materials were synthesized by the carbonization and chemical activation of agricultural bio-waste from tea woody stems (TWS), and these materials were characterized by using FTIR, SEM, TG/DTA and surface analysis (BET surface area; pore distribution; pore size, area and volume) techniques. The higher carbonization times and amount of chemical reagent generally produce the higher surface area at 400 and 500 degrees C. The experimental data demonstrated that the highest BET surface area was 789 m(2) g(-1) at 500 degrees C, 75 mu m particle size, TWS/KOH ratio of 1:2 and carbonization time of 3 h. The activated carbon IR spectrum showed the increases in intense of aromatic C-H out-of-plane bending and C=C vibrations and the disappearance of olefinic C=C functional groups. Thermal analysis curves of TWS are ascribed to decomposition of organic derivate corresponding to lignin, cellulose and hemicelluloses components up to 700 degrees C from 200 degrees C. The SEM images and textural analysis data signified that the pore development of carbon skeleton structure during carbonization and activation process formed and type of micropores in these pore structures was dominant.
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    Öğe
    Recycling of an Agricultural Bio-waste as a Novel Cellulose Aerogel: A Green Chemistry Study
    (Springer, 2020) Kaya, Mehmet; Tabak, Ahmet
    Cellulose aerogel (CA) isolated from tea stem wastes (TSW) is a good fire retardant and heat insulator, environmentally friendly, thermally stable and highly porous material with a network structure. These outstanding properties have attracted a huge interest in the materials world. In this study, firstly, following delignification and removing hemicellulose, pure raw cellulose was isolated using TSW, hydrogel form of cellulose was prepared by regeneration of cellulose solution, and then, the final product (CA) was produced via freeze-drying. The data results showed that the aerogel had a three dimensionally network structure. Moreover, it can be deduced that thermal durability of the studied CA could be effective because of its fire retardant and heat insulating property. In addition, the production process of CA is easily available at low cost and sustainable.