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    Activated carbons from co-carbonization of waste truck tires and spent tea leaves
    (Elsevier, 2021) Guclu, Cansu; Alper, Koray; Erdem, Murat; Tekin, Kubilay; Karagoz, Selhan
    This study reports the co-carbonization of waste truck tires (WTT) and spent tea leaves (STL) at different blend ratios using chemical activating reagents (KOH and ZnCl2) carried out at 800 C. The highest BET surface area from blends was 527.24 m2/g, obtained using ZnCl2 activation at a blend ratio of 1:3 (WTT/STL). Activated carbons yields in the blends were the highest at a blend ratio of 3:1 (WTT/STL) for both chemical activations. They were 24.37 wt% for KOH activation and 41.59 wt% for ZnCl2 activation. ZnCl2 activation produced higher carbon and lower oxygen content than those using KOH activation. Regardless of the type of feed, the oxygen removal efficiency of ZnCl2 was higher than that of KOH under identical conditions. Among all the activated carbons produced, the BET surface area of the activated carbons obtained from the carbonization of STL alone was highest for both activations. The BET surface area of the activated carbons produced in this study was comparable to that of activated carbons produced commercially.
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    Activated carbons from co-carbonization of waste truck tires and spent tea leaves (vol 21, 100410, 2021)
    (Elsevier, 2021) Guclu, Cansu; Alper, Koray; Erdem, Murat; Tekin, Kubilay; Karagoz, Selhan
    [No abstract available]
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    Activated Carbons From Grape Seeds By Chemical Activation With Potassium Carbonate And Potassium Hydroxide
    (Elsevier, 2014) Okman, Irem; Karagoz, Selhan; Tay, Turgay; Erdem, Murat
    Activated carbons were produced from grape seed using either potassium carbonate (K2CO3) or potassium hydroxide (KOH). The carbonization experiments were accomplished at 600 and 800 degrees C. The effects of the experimental conditions (i.e., type of activation reagents, reagent concentrations, and carbonization temperatures) on the yields and the properties of these activated carbons were analyzed under identical conditions. An increase in the temperature at the same concentrations for both K2CO3 and KOH led to a decrease in the yields of the activated carbons. The lowest activated carbon yields were obtained at 800 degrees C at the highest reagent concentration (100 wt%) for both K2CO3 and KOH. The activated carbon with the highest surface area of 1238 m(2) g(-1) was obtained at 800 degrees C in K2CO3 concentration of 50 wt% while KOH produced the activated carbon with the highest surface area of 1222 m(2)g(-1) in a concentration of 25wt% at 800 degrees C. The obtained activated carbons were mainly microporous. (C) 2013 Elsevier B.V. All rights reserved.
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    ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION ON ACTIVATED CARBON PRODUCED FROM SOYBEAN OIL CAKE BY KOH ACTIVATION
    (North Carolina State Univ Dept Wood & Paper Sci, 2012) Tay, Turgay; Erdem, Murat; Ceylan, Burak; Karagoz, Selhan
    This study presents the adsorption behavior of the methylene blue (MB) dye onto the activated carbon produced from soybean oil cake by chemical activation with KOH at 800 degrees C. The adsorption isotherms, kinetic models, and thermodynamic parameters of the adsorption were studied. The Langmuir isotherm showed a better fit than the Freundlich isotherm. The adsorption rate was described by pseudo-second-order kinetics. The negative values of Delta G degrees and the positive values of Delta H degrees indicate that the adsorption of MB was favored and endothermic.
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    Adsorption of Pb(II) and Cd(II) Ions Onto Dye-Attached Sawdust
    (Wiley, 2016) Tekin, Kubilay; Akalin, Mehmet K.; Uzun, Lokman; Karagoz, Selhan; Bektas, Sema; Denizli, Adil
    Sawdust from Pinus sylvestris was modified with Cibacron Blue F3GA. The dye was attached to the sawdust through a chemical reaction under alkaline conditions. The modified sawdust was then used to evaluate the adsorption of Pb(II) and Cd(II) ions by investigating the effects adsorption time, pH and metal ion concentration. Adsorption rates were rapid and reached equilibrium after 15min. The Langmuir isotherm was better fitted than the Freundlich isotherm for both metal ions. The maximum capacities of the monolayer adsorption were 56 mu mol/g for Pb(II) and 72 mu mol/g for Cd(II). Adsorption-desorption studies showed that Cibacron Blue F3GA-attached sawdust from P. sylvestris can be used repeatedly to adsorb heavy metal ions without significant loss of adsorptive capacity.
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    Alkali-catalyzed hydrothermal treatment of sawdust for production of a potential feedstock for catalytic gasification
    (Elsevier Sci Ltd, 2018) Imai, Akihisa; Hardi, Flabianus; Lundqvist, Petter; Furusjo, Erik; Kirtania, Kawnish; Karagoz, Selhan; Tekin, Kubilay
    This study investigates the effects of reaction temperature and catalyst loading on product yields and fuel properties of produced slurry during the alkali catalyzed hydrothermal treatment (HTT) of pine sawdust. The yield of the liquid fraction, or the aqueous product (AP), at process temperatures of 180-260 degrees C obtained after solid/liquid separation of the slurry ranged from 11.1 to 34.3 wt% on a dry, ash free basis. The fuel quality of the produced slurry, such as the elemental composition and the higher heating value (HHV), was mainly affected by the catalyst loading. An increase in the catalyst loading caused the ash content to increase. Although the increase in temperature leads to a higher liquid fraction in the slurry making it more homogeneous, its contribution to the elemental composition of the whole slurry was limited. HHV of the produced slurry ranged from 12.0 to 16.4 MJ/kg. These values are comparable to that of black liquor (BL), which has previously been shown to be a promising feedstock for gasification in a pilot scale entrained flow gasifier. These results imply the possibility of a fuel switch from BL to the HTT slurry for entrained flow gasification though its gasification reactivity and conversion characteristics must be investigated further.
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    Analytical pyrolysis of biomass using gas chromatography coupled to mass spectrometry
    (Elsevier Sci Ltd, 2014) Akalin, Mehmet Kuddusi; Karagoz, Selhan
    Biofuels represent an important category of green and alternative energy, and they have high potential to meet the energy demands of society. They are obtained from various renewable sources, which include energy crops, wood and wood wastes, agricultural by-products, and algae. Pyrolysis is an advanced technology to produce biofuels from biomass. In this review, we focus on analytical pyrolysis of biomass, in which a sample is decomposed with the help of heat treatment in an inert atmosphere. In a Py-GC-MS system, the pyrolyzer unit is connected to a gas chromatograph with a mass detector. We provide insight into the analytical pyrolysis of various biomasses and biomass components, decomposition pathways, formation of possible decomposition products and the effects of catalysts in the degradation of biomasses. Also, we discuss sample preparation and instrumentation for analytical pyrolysis. (C) 2014 Elsevier B.V. All rights reserved.
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    Anode performance of hydrothermally grown carbon nanostructures and their molybdenum chalcogenides for Li-ion batteries
    (Cambridge Univ Press, 2018) Simsir, Hamza; Eltugral, Nurettin; Frohnhoven, Robert; Ludwig, Tim; Gonullu, Yakup; Karagoz, Selhan; Mathur, Sanjay
    Three different hydrothermally grown carbonaceous materials and their molybdenum chalcogenides derived from glucose (HTC, HTC-MoO2, HTC-MoS2) were investigated to evaluate their potential as Li-ion battery anodes. All tested materials exhibited good cycling performance at a current density of 100 mA/g and showed high coulombic efficiency, >98%, after the 50th cycle. Reversible charge capacities of HTC, HTC-MoO2, and HTC-MoS2 were 296, 266, and 484 mAh/g, respectively, after 50 successive cycles. This study demonstrated that the HTC-MoS2 showed the highest reversible charge capacity which promises to be a good candidate for an environmentally friendly anode material for Li-ion batteries.
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    Application of response surface methodology to extract yields from stinging nettle under supercritical ethanol conditions
    (Elsevier Science Bv, 2013) Akalin, Mehmet Kuddusi; Karagoz, Selhan; Akyuz, Mehmet
    Response surface methodology was employed using a central composite design of experiments to optimize experimental conditions for stinging nettle extract yields under supercritical ethanol conditions. The following independent variables were investigated: extraction temperature, extraction time and plant concentration. The most significant factor was found to be the extraction temperature. A correlation coefficient was estimated to be 0.94, which demonstrates the effectiveness of the model. The values of the parameters in optimized conditions for the stinging nettle extract yield included an extraction temperature of 335 degrees C, an extraction time of 87 min, and a plant concentration of 9. A subsequent validation experiment was carried out at the optimal conditions. The validation experiment showed that the actual and predicted values for the stinging nettle extract yields were 45.3 and 42.7 wt%, respectively. The stinging nettle extracts consisted of a collection of compounds including fatty acid esters (FAE), phenols, indoles, and nitrogen containing compounds. (C) 2013 Elsevier B.V. All rights reserved.
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    Catalytic pyrolysis of waste melamine coated chipboard
    (Wiley-Blackwell, 2013) Ozbay, Gunay; Ozcifci, Ayhan; Karagoz, Selhan
    Catalytic pyrolysis of waste melamine coated chipboard was performed in a fixed-bed reactor at 400 degrees C, 500 degrees C, 600 degrees C, and 700 degrees C and a residence time of 1 h. The effects of temperature and catalysts on both product distribution and bio-oil composition were discussed. Lewis acids (AlCl3, TiCl4, and FeCl3), bases (NaOH and KOH), and basic salts (Na2CO3 and K2CO3) were used as catalysts in the pyrolysis process. The product distributions were changed depending on both the type of catalyst and temperature. Bio-oil obtained from the pyrolysis of melamine coated chipboard contained a large variety of oxygenated hydrocarbons. Phenols were found to be the major compounds identified in bio-oils for all tested runs. The bio-oils produced by Lewis acids contained aldehydes. However, the bio-oils obtained from the thermal run, the run with bases, and the run with basic salts did not contain these compounds. (c) 2011 American Institute of Chemical Engineers Environ Prog, 32: 156161, 2013.
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    Cellulose-derived carbon spheres produced under supercritical ethanol conditions
    (Springer, 2016) Tekin, Kubilay; Pileidis, Filoklis D.; Akalin, Mehmet K.; Karagoz, Selhan
    This study investigates the production of spherical carbons from cellulose under sub- and supercritical ethanol conditions with and without the addition of a potassium hydroxide (KOH) catalyst. Different temperatures (200 and 280 A degrees C), residence times (0.5, 1, 2, and 4 h), and KOH concentrations (5, 10, and 20 wt% of cellulose) were used for the carbonization process. Carbon spheres could only be obtained under supercritical ethanol conditions (at 280 A degrees C and 9.5 MPa). Supercritical ethanol decreases the oxygen content by a significant amount, thereby increasing the heating value. Morphological studies show that the carbons are essentially spherical of different sizes depending on the operating conditions (such as the presence of a catalyst and time). For the first time, we showed that spherical carbons can be obtained under supercritical ethanol conditions. This is a useful result as, for instance, ethanol can be produced from cellulose, and this opens the possibility for the development of a green and simple procedure to synthesize carbon spheres that may have many different applications including gas separation, catalysis, and energy storage.
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    Co-processing of olive bagasse with crude rapeseed oil via pyrolysis
    (Sage Publications Ltd, 2017) Ucar, Suat; Karagoz, Selhan
    The co-pyrolysis of olive bagasse with crude rapeseed oil at different blend ratios was investigated at 500oC in a fixed bed reactor. The effect of olive bagasse to crude rapeseed oil ratio on the product distributions and properties of the pyrolysis products were comparatively investigated. The addition of crude rapeseed oil into olive bagasse in the co-pyrolysis led to formation of upgraded biofuels in terms of liquid yields and properties. While the pyrolysis of olive bagasse produced a liquid yield of 52.5 wt %, the highest liquid yield of 73.5 wt % was obtained from the co-pyrolysis of olive bagasse with crude rapeseed oil at a blend ratio of 1:4. The bio-oil derived from olive bagasse contained 5% naphtha, 10% heavy naphtha, 30% gas oil, and 55% heavy gas oil. In the case of bio-oil obtained from the co-pyrolysis of olive bagasse with crude rapeseed oil at a blend ratio of 1:4, the light naphtha, heavy naphtha, and light gas oil content increased. This is an indication of the improved characteristics of the bio-oil obtained from the co-processing. The heating value of bio-oil from the pyrolysis of olive bagasse alone was 34.6 MJ kg(-1) and the heating values of bio-oils obtained from the co-pyrolysis of olive bagasse with crude rapeseed oil ranged from 37.6 to 41.6 MJ kg(-1). It was demonstrated that the co-processing of waste biomass with crude plant oil is a good alternative to improve bio-oil yields and properties.
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    Co-pyrolysis of pine nut shells with scrap tires
    (Elsevier Sci Ltd, 2014) Ucar, Suat; Karagoz, Selhan
    The co-pyrolysis of pine nut shells (PNS) with scrap tires (ST) at different blend ratios was carried out at 500 degrees C. The addition of ST into PNS in the co-pyrolysis process not only increased bio-oil yields but also improved bio-oil characteristics when compared with the pyrolysis of PNS. The carbon content in bio-oils from all PNS/ST blend ratios was higher and oxygen content was lower than that of PNS-derived oil. This is an indication of the improved characteristics of bio-oils from the co-pyrolysis of biomass with scrap tires. The blend ratio in the feedstock of co-pyrolysis had a significant effect on the product distributions and physico-chemical properties of bio-oils. When heating values of bio-oils produced from the pyrolysis of PNS were compared with bio-oils obtained from the co-pyrolysis of PNS with ST, the addition of ST into PNS led to increase heating values of bio-oils with the exception of PNS/ST (4:1)-derived bio-oil. In addition, the heating values of gas products and levels of hydrogen and hydrocarbons (from C-1 to C-4) in the gas products from the co-pyrolysis of PNS/ST blends were higher than that of the pyrolysis of PNS. The heating values of chars produced from the co-pyrolysis of PNS/ST blends were found to be in the range of 31.1 and 32.9 MJ kg (1). (C) 2014 Elsevier Ltd. All rights reserved.
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    Co-pyrolysis of waste polyolefins with waste motor oil
    (Elsevier Science Bv, 2016) Ucar, Suat; Ozkan, Ahmet R.; Karagoz, Selhan
    The co-pyrolysis of waste polyolefins [waste polyethylene (PE) and waste polypropylene (PP)] with waste motor oil (WMO) was performed at different ratios under a nitrogen atmosphere at 500 degrees C. The effects of WMO on the pyrolysis of waste polyolefins and their blends were investigated under identical conditions. The addition of WMO into waste polyolefins not only increased the liquid yields but also improved the properties of liquid products. In the most cases, the co-pyrolysis process had a positive synergistic effect on the liquid yields when compared with the calculated co-pyrolysis yields. The naphtha and paraffinic contents of the liquid products obtained from the co-pyrolysis of PE/WMO, PE/PP/WMO blends were higher than liquid products obtained from the pyrolysis of the individual waste polyolefins. The trace elements as well as heavy metals in the liquid products from the pyrolysis of WMO alone or the co-pyrolysis of waste polyolefins with WMO were observed to be lower than the WMO feed. The prominent gas products obtained from the pyrolysis of individual waste polyolefins and WMO or the co-pyrolysis of waste polyolefins/WMO blends were hydrocarbons and hydrogen. The heating values of the pyrolysis and co-pyrolysis gases were found to be in the range of 27.6-32.4 MJ Nm(-3). (C) 2016 Elsevier B.V. All rights reserved.
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    Comments on Comparative studies on liquefaction of low-lipid microalgae into bio-crude oil using varying reaction media
    (Elsevier Sci Ltd, 2022) Karagoz, Selhan
    [No abstract available]
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    Comparative studies of hydrochars and biochars produced from lignocellulosic biomass via hydrothermal carbonization, torrefaction and pyrolysis
    (Elsevier Sci Ltd, 2023) Ercan, Betul; Alper, Koray; Ucar, Suat; Karagoz, Selhan
    In this study, hydrothermal carbonization, torrefaction, and pyrolysis of hornbeam wood chips were performed. Different runs were conducted at varying temperatures ranging from 225 to 575 & DEG;C, and the resulting biochars and hydrochars were analyzed. Biochars obtained from torrefaction runs had high yields, but no significant structural changes compared to raw material. Biochars produced from pyrolysis runs had high fixed carbon content that increased with temperature. Hydrochars obtained from hydrothermal carbonization had higher degree of carbonization than biochars produced from torrefaction under identical conditions. The order of carbonization degree, from highest to lowest, was: biochars obtained from the pyrolysis process, hydrochars produced from the hydrothermal carbonization process, and biochars obtained from the torrefaction process. The highest heating value of the biochar was 32.51 MJ kg-1, produced from the pyrolysis run at 575 & DEG;C.
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    Deconstruction of lignocellulosic biomass with hydrated cerium (III) chloride in water and ethanol
    (Elsevier Science Bv, 2017) Akalin, Mehmet K.; Das, Parthapratim; Alper, Koray; Tekin, Kubilay; Ragauskas, Arthur J.; Karagoz, Selhan
    Lignocellulosic biomass was decomposed to produce crude bio-oil in water and ethanol using hydrated cerium (III) chloride as a catalyst. Use of the catalyst affected not only the yield of crude bio-oil but also the composition of bio-crude for both water and ethanol. The catalyst had a detrimental effect on the crude bio-oil yields obtained from water processing for all runs. However, in ethanol, use of the catalyst improved the crude bio-oil yields in all tested runs. The solid residue yields decreased with the catalyst use in the runs with water but increased in all studies with ethanol, except those with the shortest tested residence time of 10 min. The highest crude bio-oil yield of 48.2 wt% was obtained at 300 degrees C using 5 mmol of hydrated cerium (III) chloride at a residence time of 90 min in ethanol. The heating values of the crude bio-oils increased with the catalyst use for both water and ethanol processing. The highest heating value of 33.3 MJ kg(-1) was obtained with hydrated cerium (III) chloride at 300 degrees C and a residence time of 120 min.
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    Effect of a water-tolerant Lewis acid catalyst on the yields and properties of hydrochars from hydrothermal carbonization of walnut wood
    (Springer, 2023) Ercan, Betul; Ajagbe, Yusuf O.; Ucar, Suat; Tekin, Kubilay; Karagoz, Selhan
    The hydrothermal carbonization of walnut wood chips was conducted at 200-250 & DEG;C for 1-8 h. Increasing the hydrothermal carbonization temperature or the residence time decreased the volatile products and increased the fixed carbon content of the hydrochars. The hydrochars produced from the non-catalytic experiments at 250 & DEG;C for 6 and 8 h were in the lignite class. The lowest O/C and H/C atomic ratios were obtained after carbonization at 250 & DEG;C for 8 h. The catalytic hydrothermal carbonization experiments were carried out in the absence and presence of InCl3 using 1, 2, and 4 mmol of InCl3 at 200, 225, and 250 & DEG;C for 4 h. The highest heating value of hydrochar from the catalytic experiment was 24.73 MJ/kg and was obtained at 250 & DEG;C for 4 h using 1 mmol InCl3. Process water reuse resulted in increased heating values of the hydrochars in both the non-catalytic and catalytic experiments. The use of InCl3 promoted the coalification degree of the hydrochars. These results demonstrate that InCl3 is a suitable catalyst for producing hydrochars via the hydrothermal carbonization of walnut wood chips, which can be used as a solid biofuel.