Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Öcal, Bulutcem

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 11
    Liquefaction of Oak Wood Using Various Solvents for Bio-Oil Production
    (AMER CHEMICAL SOC, 2023) Öcal, Bulutcem; Yüksel, Aslı
    Rapidly increasing global energy demand resulting from the growing population and worldwide development has increased the consumption of limited fossil fuel. The usage causes severe environmental deterioration by CO2 emission, which has sparked interest in finding green, renewable, and sustainable alternative sources of energy. Bio-oil, derived from several biomasses via liquefaction, is a promising candidate to replace fossil fuels. Turkey's land (27%) is covered with forested areas (consisting of mostly oak trees). Therefore, it has great potential for cheap lignocellulosic feedstock forest residues from industrial applications and harvesting. In the present study, the thermal liquefaction of oak wood particles (OWP) was performed using various solvents in addition to water, namely, ethanol, 1-butanol, and 1,4-dioxane. The experiments were carried out in a batch reactor for 1 and 2 h residence times at different temperatures (210, 240, and 270 degrees C). Bio-oil samples obtained at 270 degrees C and a 1 h residence time determined as optimum conditions were analyzed with TGA, CHNS elemental analysis, FTIR, and GC-MS. 1,4-Dioxane showed the best performance in yielding the maximum bio-oil with 51.8% at those conditions. The higher heating values of the bio-oils ranged from 22.1 to 35 MJ/kg. Phenolic groups were the predominant components of bio-oil produced from OWP, while the intensity of alcohols, ketones, and acids varied based on used solvents. Based on energy recovery calculations, the enhancement of pristine OWP's energy efficiency depended on bio-oil yield, and quality was confirmed for all solvent types (1,4-dioxane > 1-butanol > water > ethanol).
  • Article
    Citation - WoS: 11
    Citation - Scopus: 12
    Treatment of Sugar Industry Wastewater by Using Subcritical Water as a Reaction Media
    (Wiley, 2023) Orak, Ceren; Öcal, Bulutcem; Yüksel, Aslı
    The sugar industry is one of the most wastewater-producing industries and it contains high content of organic and inorganic substances. Treating and reusing wastewater has significant importance because sugar industry needs to use a high volume of water. In this study, sugar industry wastewater was treated under subcritical conditions and the impacts of reaction temperature and duration over TOC removal percentage were investigated. Additionally, the impact of NaOH concentration over TOC removal percentage was examined. The highest TOC removal was obtained almost 95 % in the presence of 0.1 M of NaOH at 240 degrees C for 90 min of reaction duration. Treatment of sugar industry wastewater by subcritical water oxidation followed the second-order reaction kinetic model and the activation energy was found as 11.41 kJ/mol. Furthermore, the intermediate products were identified via GC-MS.