Gediz Uğuz

Bu çalışmada, çeşitli bitki ekstraktlarının (Achillea millefolium L., Helichrysum arenarium L. Moench ve Rosa Canina L.) biyodizelin oksidatif kararlılığı üzerindeki doğal antioksidan etkinlikleri araştırılmıştır. Bitki ekstraktları Soxhlet yöntemi ile elde edilmiş ve biyodizel-dizel karışımları üzerindeki antioksidan aktiviteleri Yüksek Performanslı Sıvı Kromatografisi (HPLC) ve Fourier Dönüşümlü Kızılötesi Spektroskopisi (FT-IR) teknikleri ile değerlendirilmiştir. Achillea millefolium L.'nin FT-IR spektrumu, ekstrakt içerisinde ferulik asit, kafeik asit ve kumarik asit varlığını gösterirken, 2959 cm-1 ve 2923 cm-1'de tespit edilen C-H gerilme titreşimleri, ekstrakt içerisinde kateşin, taksifolin ve naringenin varlığını göstermiştir. Helichrysum arenarium L. Moench ve Rosa Canina L. IR Spectra'da kaempherol, naringenin, chrysin ve butein varlığı göstermiştir. 3000 ppm konsantrasyonlu bitki özleri, %20 biyodizel ve %80 dizelden oluşan biyodizel-dizel karışımlarına doğal antioksidanlar olarak eklendi. Karışım örnekleri D100, B20D80, B20D80A, B20D80H ve B20D80R olarak isimlendirilmiştir. Kristalleşme sıcaklıkları (Tcr), Diferansiyel Taramalı Kalorimetre (DSC) ile belirlenmiştir ve sonuçlar D100, B20D80, B20D80A, B20D803000H, B20D80R için kristalleşme başlangıç ​​sıcaklıklarının sırasıyla -7,71 °C, -8,07 °C, -8,16 °C, -8,34 °C ve -8,61 °C olduğunu gösterdi. Antioksidan içeren numunelerin Tcr değerleri, antioksidan içermeyen biyodizel numunesine (B20D80) kıyasla azalmıştır. Ayrıca, numunelerin termofiziksel özellikleri belirlenmiştir ve sonuçlar, temel yakıt özelliklerinin baz yakıt numunesine bitki özlerinin eklenmesiyle hafif etkilendiğini gösterdmiştir.

In this study, the use of interior dyes with antibacterial properties was examined. Boric acid (H3BO3), which is a cheap and easily obtainable boron compound from our country's resources, has an antibacterial effect. Within the scope of the study, firstly, boric acid mixtures were prepared in appropriate concentrations and antibacterial dye production studies were carried out by adding them to indoor dyes. The antibacterial properties of the obtained dye were investigated through the inhibition effect on E. coli bacteria and its antibacterial activity was tested, and then the brightness, density, film thickness, scorching, pencil hardness and drying time tests of the dyes and the suitability of their characteristics to TS 5808/2012 and the applicability of these dyes were evaluated. The results showed that the antibacterial effect of boric acid did not have a negative effect on the dye quality, but maintained the standard values of the dye.

In this study, all solid state electrochromic devices (ECDs) without plasticizer such as propylene carbonate were fabricated by sol-gel spin coating method. WO3 nanoparticles and PEO based polymer electrolyte solutions with hBN and without hBN nanoparticles were prepared. These solutions were sol-gel spin- and dip-coated on ITO-glass, respectively. For determining the effect of hBN nanoparticles, four configuration of ECDs were fabricated. The fast bleaching and coloring times of fabricated ECDs were obtained with hBN nanoparticles in WO3 and PEO based polymer electrolyte thin films as 1.15 seconds. Glass/ITO/hBN-WO3/hBN-PEO-based-polymer electrolyte/ITO/Glass electrochromic device is turned on and off 60 times. After 60 cycle, the device coloring time changed to 2-3 seconds, bleaching times changed to 30 seconds.

Y Clove (CEO) and thyme (TEO) essential oils were added to a colza biodiesel–diesel blend (B20) as natural antioxidants, and butylated hydroxytoluene (BHT) was added as a synthetic antioxidant, at 3000 ppm concentration. Fuel properties, instrumental characterizations, engine performance, combustion characteristics, and emissions of the blends were analyzed. Fourier Transform Infrared Spectroscopy (FT-IR) spectra showed that the transmission intensities of samples increased with antioxidant addition. B20 and B20–antioxidant blends were subjected to engine tests under various loads and a fixed engine speed of 1500 rpm to determine the combustion, performance, and emissions. Engine tests revealed that antioxidants caused an increase in specific fuel consumption by 0.9–2.4% and a drop of 1.1–2.2% in thermal efficiency compared to B20. Antioxidants increased in hydrocarbons HC emission due to their oxidation-inhibitive nature, while they provided substantial improvements in smoke opacity and CO2 emission. BHT reduced NO emissions by 21% compared to B20 fuel without antioxidants. BHT was more successful in curbing NO emissions but caused an average increase in CO emissions of 3.68%. CEO-blended fuel offers better engine performance and emissions improvement than TEO-blended fuel.

The effects of thyme oil extract as an antioxidant on crystallization properties of waste cooking oil biodiesel were investigated. The inhibitory effect was determined for ASTM D7545 standard method for biodiesel added with 1000, 2000, and 3000 ppm of additives by using oxifast device and compared with the chemical antioxidant butylated hydroxytoluene (BHT). Inhibition time data were determined by converting the oxidation stability analysis results. The crystallization temperatures (T_cr) of the samples were determined by using a Differential Scanning Calorimetry (DSC) technique. T_cr values of samples with antioxidants were decreased compared to the non-antioxidant biodiesel sample (B100). The order of antioxidant power was B100<B100T1<B100T2 = B100BHT1<B100BHT2<B100T3<B100BHT3. The solid fat content (SFC %) values were determined with different antioxidant concentrations versus different times. The minimum SFC % was determined in B100T3 and B100BHT3 in 3000 ppm antioxidant concentrations in 720 min. DSC results show that the crystallization onset temperatures for B100, B100T3, and B100BHT3 were −51.83 °C, −53.59 °C, and −54.15 °C, respectively. The kinetics of crystallization was determined and k and n values were calculated. The addition of thyme oil extract as a natural antioxidant has a positive effect on biodiesel oxidative stability for all concentrations.

The huge amount of waste tires (WTs) have been disposed to surroundings which cause dangerous effect on nature. Owing to recycled WTs, the pyrolysis is a good technique to dismiss harmful effect of the WTs, by converting into gas, liquid and solid. The present study has two steps of liquefaction at a batch reactor. Firstly, conversion of the WTs into gas, waste tire oil (WTO) and char. Then the WTO were blended with calcium oxide (CaO) or natural zeolite (NZ) at different ratio and pyrolyzed to obtain high quality oil, similar to gasoline fuel (GF) or diesel fuel (DF). The distillation curve is a good key to define fuel quaility. Thus, 10% CaO-WTO blend curve near to the DF. Unfortunately, the mixture was distillated at 54 oC, lower than the DF. Therefore, the blend was separated into two fractions due to intial-final boiling points as 150 oC to 360 oC, named as Diesel like fuel (DLF); between 54 oC to 150 oC, called as gasoline like fuel (GLF). Finally, samples were analyzed to characterizate by GC, ICP-MS, TGA and DSC for similarities of conventional fuels. Based on GLF and DLF results, they can be burned in engine.

The significance of tire disposal, an attractive waste to convert into burning oil or absorber etc., has been increasing day by day. However, if it does not change into a useful form, it will damage the nature and the living things. Thus, pyrolysis, a well-known method, which is used to convert recycle tire waste into gas, liquid and char. On the other hand, the waste pyrolysis oil or waste tire oil (WTO) has a substantial avaliable calorific value similar to those of fossil fuels. Due to pyrolysis reaction, high amount of sulfur is detected in the WTO; therefore, another step of explosion applied to WTO to decrease sulfur and also re-upgrade quality of oil with such catalysts as Calcium Oxide (CaO) and Natural Zeolite (NZ) at a ratio from 2 to 10 with an increase of 2 for each step, individually. It is noticed that distillation test is a key analysis for separation discrimination of rich or lean quality fuel. As a consequence of mixture of catalyst-WTO reactions, the best curve was observed at a 10% CaO-WTO mixture which was close to diesel#2 and the mixture was separated into two new fuels as light (Gasoline Like Fuel or abbreviated as GLF) and heavy one (Diesel Like Fuel or shortened as DLF) due to temperature differences. According to distillation, FT-IR, NMR and UV–vis were used to analyze WTO, GLF and DLF for defining their characterization as well. Thus, the characterization result data of samples have quasi-equivalent with standard petroleum in open literature, and can be combusted in engine as well.