Özgür Sönmez Özgür Sönmez FEN FAKÜLTESİ KİMYA BÖLÜMÜ ORGANİK KİMYA ANABİLİM DALI Kimya
Araştırmacının yayınlarını daha detaylı bir şekilde aramak veya filtrelemek için buraya tıklayabilirsiniz.

Microwave-assisted biodiesel production from waste cooking oil using pyrrolidonium ionic liquid catalyst: optimization, kinetic and thermodynamic studies

Gözmen, Belgin | Sönmez, Özgür

Biodiesel production from waste cooking oil (WCO) has been gaining popularity due to its economical and eco-friendly nature. This study aimed to produce an environmentally friendly fuel by recycling WCO. Using pyrrolidonium-based Brønsted acidic ionic liquid (IL) as a catalyst, microwave-assisted transesterification of WCO was used to produce biodiesel. Reaction conditions, including temperature, catalyst amount, methanol/oil molar ratio, and reaction time, were optimized using response surface methodology (RSM) based on Box-Behnken design (BBD). A biodiesel conversion of 97.3 % was achieved at 115 °C, for 120 min, with 10 % catalyst loading, and a 24:1 methanol/oil molar ratio. The kinetics of the transesterification reaction was investigated, with the activation energy determined to be 13.67 kJ mol−1. The thermodynamic values were also calculated, ΔH = 10.6 kJ mol−1, ΔS = − 252.53 J mol−1 K−1 and ΔG = 99.7–109.8 kJ mol−1. Thus, the microwave-assisted transesterification reaction was endothermic, endergonic, and non-spontaneous. The IL catalyst demonstrated excellent reusability, maintaining high activity for six consecutive cycles. In addition, the quality of WCO biodiesel met the ASTM D6751 standard. Pyrrolidonium-based ILs are effective catalysts for biodiesel production owin...

Esterification of oleic acid using CoFe2O4@MoS2 solid acid catalyst under microwave irradiation

Sönmez, Özgür | Gözmen, Belgin

Ensuring highly efficient biodiesel production requires catalysts. Therefore, developing heterogeneous catalysts capable of being recovered and reused without compromising effectiveness is crucial. In this context, the CoFe2O4@MoS2 heterogeneous magnetic acid catalyst was synthesized and characterized in detail by XRD, SEM-EDX, BET surface area, magnetic property and acid strength. Finally, the catalytic performance of this catalyst was evaluated for the esterification of oleic acid by microwave-assisted method. The fabricated CoFe2O4@MoS2 catalyst has a strong saturation magnetization of 15.78 emu/g, a surface area of 6.70 m2/g, and a high acid loading of 2.1 mmol H+/g, according to the characterization data. The highest oleic acid conversion of 98.2 % was achieved under the optimum conditions (7.5 wt% catalyst amount, 15:1 methanol to oleic acid molar ratio, 2 h reaction time, and 140 °C temperature). To study a comparison between heating methods, the esterification reaction was carried out under conventional heating and microwave heating was found to significantly reduce the reaction time from 4 to 2 h. The catalytic activity did not decrease considerably after eight times use, indicating that the composites exhibited strong stability and recycling capability.

Evaluation of sewage sludge biochar and modified derivatives as novel SPE adsorbents for monitoring of bisphenol A

Gözmen, Belgin | Sönmez, Özgür

Sewage sludge is abundant biomass, the sustainable management of which remains a big issue worldwide. It was demonstrated that pyrolysis of sewage sludge using simple and cost-effective apparatus can produce biochars, suitable for solid-phase extraction applications of hydrophobic analytes. Detailed characterization showed that modification lead to three more hydrophobic and one more hydrophilic sample, compared to the original biochar. All samples were evaluated in the solid-phase extraction of the emerging contaminant Bisphenol A from aqueous solutions. KOH-SSB and KOH/MeOH-SSB exhibited the most promising behavior, with the latter achieving recoveries of 88.1%, at a quantity of 0.1 g at the natural pH of the BPA solution (6.5). The effect of solution pH was insignificant in the range of 4–7, whereas the initial BPA concentration had no effect in the recovery within the range of 1–100 μg L−1. The mechanism of interaction between the optimum sample and BPA was based on hydrogen bonding and π-π interactions, establishing earlier observations that the type (and not concentration) of individual surface groups and the total surface area play a significant role in the process.

Microwave-assisted d-pinitol extraction from carob: application of Box–Behnken design

Gözmen, Belgin | Sönmez, Özgür

This study investigates the effects of temperature (50–80 °C), time (10–60 min), carob-to-solvent ratio (2–8 g/40 mL), and solvent concentration (0–50 ethanol/water%, v/v) on microwave-assisted extraction of d-pinitol compound from carob fruit with optimization using Box–Behnken design. The optimal conditions for maximum d-pinitol yield (64.16 g/kg dry sample) include 50 °C temperature, 5.6 g carob/40 mL solvent, water used as a solvent, and an extraction time of 10 min. The fitness of the model was determined by ANOVA analysis with a high coefficient (R2 = 0.9057). Extraction was performed under optimum conditions for model validation, and 63.89 g/kg dry sample of d-pinitol extraction was achieved. In addition, the effects of the same variables on the total phenolic (TP) content of MEA extraction of carob were also investigated. Extraction efficiency of 426 g/kg was obtained under the optimum conditions determined for TP (80 °C, 8 g of carob, 50% ethanol, and 10 min), but it was observed that TP content decreased to 49.7 g/kg under optimum conditions determined for d-pinitol. Sucrose, glucose, and fructose sugar contents of the extract were determined only for optimum conditions for d-pinitol, and the fructose content was found to be the lowest. Determining the d-pinitol, TP, an...

Comparative mineralization of Basic Red 18 with electrochemical advanced oxidation processes

Gözmen, Belgin | Sönmez, Özgür

In this study, the role of electrochemical oxidation processes, including the electro-Fenton, the electro-persulfate (PS), and the electro/FeII /PS processes, in the removal of Basic Red 18 (BR18) from aqueous solutions was investigated. It was found that the electro-PS process successfully removes colour, but after 5 h, it produced only 75 % mineralization. In the same conditions, more effective mineralization was achieved by the electro/FeII/PS process than by the electro-Fenton method. At pH levels of 3.0 and 5.7, very effective mineralization results were produced by the electro/FeII/PS process. Moreover, the maximum mineralization current efficiency values were obtained by the electro/FeII/PS process. The mineralization efficiency of the electro/FeII/PS process was determined to be 97 % under the following conditions: BR18 initial dye concentration of 100 mg L-1, pH of 5.7, contact time of 5 h, PS concentration of 10 mM, Fe2+ concentration of 0.2 mM, and a sodium sulfate concentration of 0.05 M.

Influence of the addition of various ionic liquids on coal extraction with NMP

Sönmez, Özgür | Gözmen, Belgin

In this work, two Turkish coals were extracted with N-methyl-2-pyrrolidone (NMP) and NMP containing a small amount of ionic liquids (ILs) under reflux conditions at atmospheric pressure. The effects of coal type, ionic liquid type, ionic liquid-to-coal ratio, and ultrasonic interactions on extraction yield were investigated. The ILs used were: 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), 1-buty-4- methylpyridinium chloride ([Bmp]Cl), 1-ethyl-3-methylimidazolium chloride ([Emim]Cl), and 1-butyl-2,3-dimethylimidazolium chloride ([Bdmim]Cl). It was found that the extraction yield of coals using NMP/ILs varied with coal type, IL type and amount of IL. ILs were effective on the extraction of Afsin-Elbistan (AE) lignite, but not on the extraction of Üzülmez (UZ) coal. A significant increase in extraction yield for AE lignite was observed when a small amount of IL was added into NMP. It was determined that [Bmim]Cl was the most efficient IL used for the extraction of lignite compared to the others ILs used, and the extraction efficiency was found to increase by increasing the amount of ionic liquid added into NMP.

Optimization of solvent extraction process of some Turkish coals using response surface methodology and production of ash-free coal

Gözmen, Belgin | Sönmez, Özgür

In order to produce ash-free coal (AFC) from three Turkish coals, solvent extraction of coals using 1-methylnaphthalene (1-MN) at different temperatures were conducted. The extraction yield of coals was found dependenton coal, temperature, and solvent type. When there was usage of 1-MN as solvent, the extraction yield was low. However,on addition of N-methyl-2-pyryrolidone (NMP) or quinoline (QN) into 1-MN, the extraction yield increased. Following theextractions, we obtained AFC with less than 0.65% ash content for the three coals used in this study. The response surfacemethodology (RSM) was employed to investigate the solvent extraction conditions. The factors investigated were extractiontemperature and additional polar solvent ratio. The obtained results demonstrated that either excess amount of polar solventinto 1-MN should be added at low temperatures or extraction should be done at high temperatures using less polar solvent toobtain an increase in extraction efficiency. The sensitivity and validity of results obtained by RSM were confirmed throughvalidation experiments. The results of validation experiments showed a good agreement between the experimental andpredicted values (relative error